Re: [time-nuts] Low noise power supplies
Chris wrote: Just practical question.. How would one measure noise at this level? If I were evaluate this what would I need? Generally, one starts with an extremely low noise amplifier. Note that isolating the very low frequency AC components from the DC component is a substantial difficulty (we are interested in AC noise well below 1 Hz). For example: http://www.edn.com/design/analog/4313942/Characterizing-noise-in-high-performance-voltage-reference-ICs See also: Linear Technology Application Notes 124 and 83 Bruno Neri, et al., Ultra Low-Noise Preamplifier for Low-Frequency Noise Measurements in Electron Devices, IEEE Transactions On Instrumentation And Measurement, Vol. 40. No. I. February 1991 Felix A. Levinzon, Ultra-Low-Noise High-Input Impedance Amplifier for Low-Frequency Measurement Applications, IEEE Transactions On Circuits And Systems - I: Regular Papers, Vol. 55, No. 7, August 2008 Some spectrum analyzers with cross-correlation capabilities can get you in the ballpark if you let them average long enough, although you are much better off if you use an ELN amplifier there, too. Best regards, Charles ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Low noise power supplies?
Charles et al, http://www.pst.netii.net/spice/ripple/ripple.htm holds some interesting spice simulations of various refinement techniques. Best regards Ulrich Bangert -Ursprungliche Nachricht- Von: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] Im Auftrag von Charles P. Steinmetz Gesendet: Freitag, 1. Februar 2013 18:35 An: Discussion of precise time and frequency measurement Betreff: Re: [time-nuts] Low noise power supplies? Joe wrote: Back when I was in product engineering there was a VCO design that used a superfilter circuit. It consisted of a pass transistor and a filter cap from base to ground. The gain of the transistor multiplied the effective capacitance. I have not seen this configuration since. They are often called capacitance multipliers and are popular with (among others) audio designers as low-noise supplies for low-level circuits (moving coil head amps, RIAA stages, etc.). They are best used following an active regulator. If the capacitor is electrolytic, it needs to be chosen very carefully so that leakage current noise doesn't spoil the effort. Also, it is best to use a voltage divider on the base to give the transistor a bit of headroom (i.e., base voltage should be a volt or so lower than collector voltage, not the same as the collector voltage as happens when there is just a pull-up resistor on the base). Best regards, Charles ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Low noise power supplies?
Are 4 and 5 regulated? Or is the zener picked to compensate for the VBE drops? Any of these circuits where the output transistor is in an emitter follower configuration will have its noise effected by the load current, since that current directly effects the output transistor transconductance. The load in all cases was a couple hundred mA worth of resistance at the voltage in question, as I recall. It's been a few years since I captured these plots. The Zeners were just whatever parts came to hand, 1N474x parts basically. I didn't care about the 1.4V drop across the Darlington, just the resulting noise. -- john Miles Design LLC ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Low noise power supplies?
Bob Camp, Thursday, January 31 11:36 AM (Local NY time): ((...snip...)) With a good enough voltmeter you could carry the analogy one step further and compute an ADEV like number on the output voltage. I suspect that's carrying things a bit far. No, I disagree. That's not carrying things nearly far enough. I really think we should figure out a reliable methodology for this sort of thing. This is time nuts after all, so perhaps some time/frequency applications might end up needing sub-nanovolt regulation (and there are those whom might simply need it because they're nuts) Tom Van Baak, Thursday, January 31, 2013 9:43 AM (Local NY time): ((...snip...)) I was never quite satisfied with the outcome of comparing a half dozen power supplies this way: http://www.leapsecond.com/pages/tbolt/noise.htm We have rigorous ways to compare and report oscillator performance; both as numbers and as plots. Is there something equivalent for power supplies? Thanks Tom. I found that writeup about various power supplies rather useful. I'm doing some research and development for power supplies right now, and hope to come up with something completely nuts by the time I'm ready to go from learning how to work with thunderbolts / GPS Disciplined OCXO to something exotic which, today, might be far over my head. --Sarah ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Low noise power supplies?
Hi Bert, No need to block the DC. These instruments already have DC blocks (and a switchable low current DC sink to hold the line from the exchange) because the telephone line has a DC voltage of typically 48V on it already. For comparison I just use 600 ohm termination and dBm, dBmV can be calculated or use a look-up table. To compare a batch you can zero the meter on the first or known good unit and just read the delta. Robert G8RPI. From: Burt I. Weiner b...@att.net To: time-nuts@febo.com Sent: Thursday, 31 January 2013, 19:19 Subject: [time-nuts] Low noise power supplies? Bob, I have a pair of HP-3551A's*. I'm very familiar with making transmission lines measurements, and it seems that measuring power supply noise would be the same, except that you want to block the DC from the input of the instrument. What has your procedure been and what numbers have you come up with? Since these instruments read in dBm0, do you reference from the supply's voltage and then convert to mV (difference)? * One that I picked up off eBay for $75.00 looks new and came with the complete manual, and the battery will run it most of the day. Thanks, Burt, K6OQK Subject: Re: [time-nuts] Low noise power supplies? A non-standard but repeatable way to measure power supply noise is to use a Transmission Impairment Measuring Set (TIMS) such as the HP3945(6)A or 3551 (2)A. These were intended for use in pairs to assess analog telephone lines for data use. As well as an AF generator, frequency counter, amplifier, monitor speaker and level meter they will measure broadband noise. Being designed for POTS they will also withstand at least 50V DC at the input while measuring the noise. You can also apply internal filters if required. The last digit designates a North American? (BELL) or European (CCITT) standard unit, but broadband noise is the same. They can be picked up really cheaply now (list was$3000-$5000) and make a nice compact audio test set. Robert G8RPI. Burt I. Weiner Associates Broadcast Technical Services Glendale, California U.S.A. b...@att.net www.biwa.cc K6OQK ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Low noise power supplies?
Hi The circuit I described, is (as stated) quiet down to 100 Hz. It's 3 db bandwidth is well below 10 Hz with the 47 uF cap. If you need it quiet down to 10 Hz or 0.1 Hz, you will need to buy a few more caps. It's still not rocket science. For most OCXO or atomic standard testing applications out there, 10 Hz is low enough. Bob On Jan 31, 2013, at 9:41 PM, Charles P. Steinmetz charles_steinm...@lavabit.com wrote: Bob wrote: An AD 797, a couple of metal film resistors, and a fairly large (say 47 uf) plastic cap work pretty well. The band from 10 Hz down to 0.1 or 0.01 Hz is generally important when testing oscillators. To keep the 797 input noise density below a few nV per root Hz, the terminations must have very low resistance. With such low resistance, a 47 uF cap won't even get you to 10 Hz, much less 0.1 or 0.01 Hz. One more thought: Many oscillators have internal regulators that are not nearly as good as what you can build. No sense using an external supply with 5 nV per root Hz noise density if it will be re-regulated inside the oscillator by a circuit that has a noise density of 250 nV per root Hz. Best regards, Charles ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Low noise power supplies?
Linear Technology application note 83 Performance Verification of Low Noise, Low Dropout Regulators holds some interesting information. I am however unsure whether what was low noise in 2000 is still low noise in 2013 Best regards Ulrich Bangert -Ursprungliche Nachricht- Von: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] Im Auftrag von Bob Camp Gesendet: Freitag, 1. Februar 2013 13:38 An: Discussion of precise time and frequency measurement Betreff: Re: [time-nuts] Low noise power supplies? Hi The circuit I described, is (as stated) quiet down to 100 Hz. It's 3 db bandwidth is well below 10 Hz with the 47 uF cap. If you need it quiet down to 10 Hz or 0.1 Hz, you will need to buy a few more caps. It's still not rocket science. For most OCXO or atomic standard testing applications out there, 10 Hz is low enough. Bob On Jan 31, 2013, at 9:41 PM, Charles P. Steinmetz charles_steinm...@lavabit.com wrote: Bob wrote: An AD 797, a couple of metal film resistors, and a fairly large (say 47 uf) plastic cap work pretty well. The band from 10 Hz down to 0.1 or 0.01 Hz is generally important when testing oscillators. To keep the 797 input noise density below a few nV per root Hz, the terminations must have very low resistance. With such low resistance, a 47 uF cap won't even get you to 10 Hz, much less 0.1 or 0.01 Hz. One more thought: Many oscillators have internal regulators that are not nearly as good as what you can build. No sense using an external supply with 5 nV per root Hz noise density if it will be re-regulated inside the oscillator by a circuit that has a noise density of 250 nV per root Hz. Best regards, Charles ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Low noise power supplies?
Hello, interesting discussion about noise. It's all way over my knowledge, so my contribution to discussion maybe is only noise :) Re batteries I agree with Mark, see below: Il 2013-01-31 06:42 Mark Sims ha scritto: A123 20Ah LiFePO4 cells have an internal resistance in the milliohm range. Their M1 26650 format cells are around 8 milliohms. Most high capacity (3000 mAh) 18650 style lithium cells are around 10-15 milliohms. I made some tests of high rate RC batteries, and their internal resistance seem to be below 10mOhm These are Li-ion pouch cells, their selfdischarge seem very low, but I dont have figures for this. Their cost is very low, and are used for RC airplanes or cars, only thing I'm expecting is that they will age and their internal resistance (and capacity) probably will worsen after some time. This is a graph of a 3-cell battery of 1.8Ah capacity, charged and discharged at 3.6A and 7.2A (red and blue curves): http://www.eevblog.com/forum/reviews/high-rate-li-ion-batteries/?action=dlattach;attach=31097 Here tested up to maximum declared rate: http://www.eevblog.com/forum/reviews/high-rate-li-ion-batteries/?action=dlattach;attach=31185 I report this here about noise, because I remember that while I was charging and discharging them, I was watching with awe the voltmeter stable readings. The power supply/load was an HP6632B and the meter a keithley 2015, the meter reading was stable up to last digit (10uV over 10-11V)and counting digit by digit up while charging or down while discharging, no missing codes sort of thing :) It was like watching a counter instead of a voltmeter. So I was wondering what could be the real noise of a chemical battery. Reading this discussion I'm learning that the batteries can be low noise voltage sources. Thanks, Fabio. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Low noise power supplies?
Hi If you use an electrolytic cap on the base (tantalum or what ever) the leakage current will mess up the output a bit. It does *eventually* die down some, but you may have to wait for days... Bob -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of M. Simon Sent: Friday, February 01, 2013 9:11 AM To: time-nuts@febo.com; jleik...@leikhim.com Subject: [time-nuts] Low noise power supplies? Joe, I'm using that in my low power (150ma) supplies. I add a zener to the base (darlington) circuit for pre-regulation. Since I'm doing a line operated linear supply the fall off of gain with frequency is not of too much concern. Once I finish testing (I have boards in hand - I need to order parts) I will publish. Simon Message: 6 Date: Thu, 31 Jan 2013 15:39:02 -0500 From: Joe Leikhim jleik...@leikhim.com To: time-nuts@febo.com Subject: [time-nuts] Low noise power supplies? Message-ID: 510ad666.8090...@leikhim.com Content-Type: text/plain; charset=ISO-8859-1; format=flowed Back when I was in product engineering there was a VCO design that used a superfilter circuit. It consisted of a pass transistor and a filter cap from base to ground. The gain of the transistor multiplied the effective capacitance. I have not seen this configuration since. -- Joe Leikhim Leikhim and Associates Communications Consultants Oviedo, Florida jleik...@leikhim.com 407-982-0446 WWW.LEIKHIM.COM Engineering is the art of making what you want from what you can get at a profit. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Low noise power supplies?
Ok, but open loop as I described? I bicmos design, there are two common junk buffers. The junkiest (sp?) is going up a PNP and down a NPN. No feedback. You live with the vbe mismatch. Next up the food chain is the long tail pair (diff amp) with emitter follower. With one gain stage, it is reasonable stable. -Original Message- From: John Miles jmi...@pop.net Sender: time-nuts-boun...@febo.com Date: Fri, 1 Feb 2013 01:30:24 To: 'Discussion of precise time and frequency measurement'time-nuts@febo.com Reply-To: Discussion of precise time and frequency measurement time-nuts@febo.com Subject: Re: [time-nuts] Low noise power supplies? Are 4 and 5 regulated? Or is the zener picked to compensate for the VBE drops? Any of these circuits where the output transistor is in an emitter follower configuration will have its noise effected by the load current, since that current directly effects the output transistor transconductance. The load in all cases was a couple hundred mA worth of resistance at the voltage in question, as I recall. It's been a few years since I captured these plots. The Zeners were just whatever parts came to hand, 1N474x parts basically. I didn't care about the 1.4V drop across the Darlington, just the resulting noise. -- john Miles Design LLC ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Low noise power supplies?
Content-Type: text/plain; charset=ISO-8859-1 In message 2bf4f4e8c8207ae0f94a7e1a1e63c...@quipo.it, Fabio Eboli writes: Il 2013-01-31 06:42 Mark Sims ha scritto: A123 20Ah LiFePO4 cells have an internal resistance in the milliohm range. [...] Low internal resistance in batteries is an indicator of low noise, but not a guarantee of low noise. For instance in wet lead-acid cells, turbulence in the liquid as the density changes can lead to low-frequency noise, which incidentally sounds a lot like a pot of stew simmering. -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 p...@freebsd.org | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Low noise power supplies?
Joe wrote: Back when I was in product engineering there was a VCO design that used a superfilter circuit. It consisted of a pass transistor and a filter cap from base to ground. The gain of the transistor multiplied the effective capacitance. I have not seen this configuration since. They are often called capacitance multipliers and are popular with (among others) audio designers as low-noise supplies for low-level circuits (moving coil head amps, RIAA stages, etc.). They are best used following an active regulator. If the capacitor is electrolytic, it needs to be chosen very carefully so that leakage current noise doesn't spoil the effort. Also, it is best to use a voltage divider on the base to give the transistor a bit of headroom (i.e., base voltage should be a volt or so lower than collector voltage, not the same as the collector voltage as happens when there is just a pull-up resistor on the base). Best regards, Charles ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Low noise power supplies?
Sorry, Poul-Henning Kamp, I answered directly to your mail address, I repost it here... Il 2013-02-01 18:09 Poul-Henning Kamp ha scritto: Content-Type: text/plain; charset=ISO-8859-1 In message 2bf4f4e8c8207ae0f94a7e1a1e63c...@quipo.it, Fabio Eboli writes: Il 2013-01-31 06:42 Mark Sims ha scritto: A123 20Ah LiFePO4 cells have an internal resistance in the milliohm range. [...] Low internal resistance in batteries is an indicator of low noise, but not a guarantee of low noise. I have no reason to disagree with your statement :) I was agreeing with Mark about the fact that there are new chemistries with low internal resistance, and nice characteristics like low cost, availability and low self discharge, and that some Li-ion can be built to be one of those. For instance in wet lead-acid cells, turbulence in the liquid as the density changes can lead to low-frequency noise, which incidentally sounds a lot like a pot of stew simmering. It would be interesting to see if there are references about noise in the li chemistries. Fabio. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Low noise power supplies?
Well, I stand corrected. Weren't the TM 500 instruments marketed as low cost? Regards. Max. K 4 O DS. Email: m...@maxsmusicplace.com Transistor site http://www.funwithtransistors.net Vacuum tube site: http://www.funwithtubes.net Woodworking site http://www.angelfire.com/electronic/funwithtubes/Woodworking/wwindex.html Music site: http://www.maxsmusicplace.com To subscribe to the fun with transistors group send an email to. funwithtransistors-subscr...@yahoogroups.com To subscribe to the fun with tubes group send an email to, funwithtubes-subscr...@yahoogroups.com To subscribe to the fun with wood group send a blank email to funwithwood-subscr...@yahoogroups.com - Original Message - From: David davidwh...@gmail.com To: Discussion of precise time and frequency measurement time-nuts@febo.com Sent: Thursday, January 31, 2013 11:10 PM Subject: Re: [time-nuts] Low noise power supplies? I have seen it used in a couple of Tektronix TM500 instruments but the purpose may have been to generate a lower voltage power supply rail instead of noise reduction. Tektronix often added LC sections on their switching power supply outputs and distributed smaller LC sections to prevent coupling between different circuits. On Thu, 31 Jan 2013 22:12:42 -0600, Max Robinson m...@maxsmusicplace.com wrote: You haven't seen it used because it doesn't work very well. It appeared in a few pieces of Heathkit equipment but I don't think HP or Tek used it at all. Any AC component of base to collector voltage has a small but definite effect on Vbe which transfers voltage in the reverse direction from collector to emitter even though the base is held at AC ground. A three terminal regulator does a better job of suppressing ripple from a power supply. Regulators use a zener diode as the reference and there are circuits in which a zener is used as a noise source. What does that tell you? The quietest power supply is an analog regulator followed by one or more RC filter sections. The inductor in an LC filter is likely to pick up more hum and noise than it filters out. My presumption is that a low noise power supply is likely to be providing a small amount of power to the load and load regulation is probably not a problem. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Low noise power supplies?
This is a keeper. Note the strong peak at 60 Hz for the unfiltered darlington. Regards. Max. K 4 O DS. Email: m...@maxsmusicplace.com Transistor site http://www.funwithtransistors.net Vacuum tube site: http://www.funwithtubes.net Woodworking site http://www.angelfire.com/electronic/funwithtubes/Woodworking/wwindex.html Music site: http://www.maxsmusicplace.com To subscribe to the fun with transistors group send an email to. funwithtransistors-subscr...@yahoogroups.com To subscribe to the fun with tubes group send an email to, funwithtubes-subscr...@yahoogroups.com To subscribe to the fun with wood group send a blank email to funwithwood-subscr...@yahoogroups.com - Original Message - From: John Miles jmi...@pop.net To: 'Discussion of precise time and frequency measurement' time-nuts@febo.com Sent: Friday, February 01, 2013 12:03 AM Subject: Re: [time-nuts] Low noise power supplies? Awhile back I ran some baseband plots of various supplies with an HP 3048A (image attached). In my experience measuring actual OCXOs, an LM317T or LM338K is quiet enough to avoid influencing oscillator PN. With these variable-voltage parts, you can bypass the reference pin for some additional improvement, but I don't believe I did that for these plots. It's easy to spot the difference between a 7812/7815 and an LM317T (see red versus green/white traces). As a lazy approach, try measuring the oscillator with both a 78XX and an LM317T. Because the 78XX is about 10 dB noisier across most of the spectrum, If you don't see a difference, you can assume that further optimization is pointless. Near 1 Hz this call may be questionable. If you don't need an LDO, don't use one. If you do, use the quietest part you can find. The best LDOs seem to be about as quiet as an ordinary LM317T. I've mentioned before that you need to be careful with large LC filters downstream of the regulator. A good power source will exhibit a low impedance at ALL offsets of interest. You sometimes see NIST circuits where the power is conditioned by a Darlington emitter follower whose base is fed with an RC-filtered Zener diode. The purple and orange traces are pretty informative with regard to that approach. On the orange trace, where the only filtering is the RC network between the Zener and the base, notice how the noise becomes worse than all of the other sources below 10 Hz. Here, the RC filter on the Zener becomes less effective and the Darlington pair obligingly amplifies the diode noise. An additional LC filter after the regulator may have the effect of herding the entire noise spectrum into a high-Q peak, even though the LC corner frequency is much higher than the RC filter in the base circuit (violet trace). Depending on your OCXO's supply rejection characteristics this could be a good thing or a bad thing. Finally, make sure the OCXO has good RF bypassing where its power supply pin enters the case. If in doubt, solder a 0.1 uF ceramic right at the point of entry. I've seen $2000 Wenzels that didn't bother doing this. I'm sure they looked good in a screen room. -- john Miles Design LLC -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts- boun...@febo.com] On Behalf Of Richard (Rick) Karlquist Sent: Wednesday, January 30, 2013 6:17 PM To: Discussion of precise time and frequency measurement Subject: [time-nuts] Low noise power supplies? I know this topic has been discussed in the past on the list, but a colleague is asking if there are any off the shelf low noise power supplies for testing oscillators. Something a cut above an HP brick lab power supply etc. They are hoping to avoid having to homebrew a power conditioning circuit. Did we ever arrive at a concensus as to the state of the art in homebrew power conditioning circuits? Any help would be appreciated. Rick Karlquist N6RK ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi- bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Low noise power supplies?
Well the Tek current probe that goes in the power supply wasn't low cost. They also had a nice bench supply that went in the box. But a lot of the instruments weren't so fancy. -Original Message- From: Max Robinson m...@maxsmusicplace.com Sender: time-nuts-boun...@febo.com Date: Fri, 1 Feb 2013 13:39:14 To: Discussion of precise time and frequency measurementtime-nuts@febo.com Reply-To: Discussion of precise time and frequency measurement time-nuts@febo.com Subject: Re: [time-nuts] Low noise power supplies? Well, I stand corrected. Weren't the TM 500 instruments marketed as low cost? Regards. Max. K 4 O DS. Email: m...@maxsmusicplace.com Transistor site http://www.funwithtransistors.net Vacuum tube site: http://www.funwithtubes.net Woodworking site http://www.angelfire.com/electronic/funwithtubes/Woodworking/wwindex.html Music site: http://www.maxsmusicplace.com To subscribe to the fun with transistors group send an email to. funwithtransistors-subscr...@yahoogroups.com To subscribe to the fun with tubes group send an email to, funwithtubes-subscr...@yahoogroups.com To subscribe to the fun with wood group send a blank email to funwithwood-subscr...@yahoogroups.com - Original Message - From: David davidwh...@gmail.com To: Discussion of precise time and frequency measurement time-nuts@febo.com Sent: Thursday, January 31, 2013 11:10 PM Subject: Re: [time-nuts] Low noise power supplies? I have seen it used in a couple of Tektronix TM500 instruments but the purpose may have been to generate a lower voltage power supply rail instead of noise reduction. Tektronix often added LC sections on their switching power supply outputs and distributed smaller LC sections to prevent coupling between different circuits. On Thu, 31 Jan 2013 22:12:42 -0600, Max Robinson m...@maxsmusicplace.com wrote: You haven't seen it used because it doesn't work very well. It appeared in a few pieces of Heathkit equipment but I don't think HP or Tek used it at all. Any AC component of base to collector voltage has a small but definite effect on Vbe which transfers voltage in the reverse direction from collector to emitter even though the base is held at AC ground. A three terminal regulator does a better job of suppressing ripple from a power supply. Regulators use a zener diode as the reference and there are circuits in which a zener is used as a noise source. What does that tell you? The quietest power supply is an analog regulator followed by one or more RC filter sections. The inductor in an LC filter is likely to pick up more hum and noise than it filters out. My presumption is that a low noise power supply is likely to be providing a small amount of power to the load and load regulation is probably not a problem. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Low noise power supplies?
Content-Type: text/plain; charset=ISO-8859-1 In message blu170-w704bd0870332925fa3e67dce...@phx.gbl, Mark Sims writes: A123 20Ah LiFePO4 cells have an internal resistance in the milliohm range. Their M1 26650 format cells are around 8 milliohms. Most high capacity (3000 mAh) 18650 style lithium cells are around 10-15 milliohms. different chemistries have different levels of noise, and I belive Lithium is not in the good end of the spectrum there. As I understood the general theory: batteries have more noise the further the electrodes are from being pure metals, so maybe the best and lowest noise is to build a volta-pile ? -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 p...@freebsd.org | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Low noise power supplies?
Content-Type: text/plain; charset=ISO-8859-1 In message bay162-w38a3ac22812ac79a0fbfc6df...@phx.gbl, Tom Knox writes: Starting with a hp supply this finesse regulator will really clean up the output. http://www.wenzel.com/documents/finesse.html I've played with that, and it can do impressive things. However, to big caveats: 1. It's very temperature sensitive so on average you only get tens of dB, not hundred dB damping. 2. Noise which comes in from the load gets amplified. -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 p...@freebsd.org | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Low noise power supplies?
I've measured AA nicad impedance at a few kHz, but it was years ago. My recollection is it was in tens of milliohms. ESR does have a frequency dependency. In the same time frame, I was trying to find a simple non-instrusive way to detect alkaline cells versus nicads. The key was in impedance versus frequency curve. It looked more than a bit hair brained, and given that there are no consumer devices that do automatic detection today, I gather no one else found an elegant solution. But low ESR may not translate to low noise. Yeah, I know everyone is thinking thermal noise, but a battery is a chemical device. You can detect gas bubbles from electrical artifacts in some types of batteries. At least under high discharge. Also the impedance of nicads increases when they get old. I spent a ridiculous amount of time dealing with a customer that found some old batteries that were not being detected by the safety scheme built into a particular chip. Lastly, the chemistry in these batteries isn't constant. Once you have one battery technology nailed down, they increase the capacity and it is a new ballgame. That lead to chemistry independent charging schemes where the chargers had uP interface so that the charging could be tweaked by the customer. Personally, if the device you are using needs a power supply from god, it wasn't designed well. The manufacturer should incorporate the required regulation in the product so that it meets spec with run of the mill supplies. Nobody likes to spend time debugging some customer complaint due to a component outside your product. On 1/30/2013 9:44 PM, Arthur Dent wrote: But the only NiCd I know about are the AA sized ones. I have some of the wet NiCd batteries that are capable of putting out 200A continuously. I'm assuming the internal resistance is pretty low. ;-) Arthur ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Low noise power supplies?
Poul-Henning Kamp wrote: Content-Type: text/plain; charset=ISO-8859-1 In messagebay162-w38a3ac22812ac79a0fbfc6df...@phx.gbl, Tom Knox writes: Starting with a hp supply this finesse regulator will really clean up the output. http://www.wenzel.com/documents/finesse.html I've played with that, and it can do impressive things. However, to big caveats: 1. It's very temperature sensitive so on average you only get tens of dB, not hundred dB damping. 2. Noise which comes in from the load gets amplified. With some care its possible to make the emitter current of the shunt transistor approximately PTAT so that, at least for small signals the temperature dependence of the rejection is reduced significantly. Its also possible to build a feedback style shunt regulator that has considerably higher supply rejection than the Wenzel circuit using an opamp and a shunt transistor together with a small resistance in series with one of the supply leads. Bruce ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Low noise power supplies?
On 1/31/2013 12:20 AM, Bruce Griffiths wrote: With some care its possible to make the emitter current of the shunt transistor approximately PTAT so that, at least for small signals the temperature dependence of the rejection is reduced significantly. Sorry, what does PTAT mean? I'm not familiar with that term. Its also possible to build a feedback style shunt regulator that has considerably higher supply rejection than the Wenzel circuit using an opamp and a shunt transistor together with a small resistance in series with one of the supply leads. Bruce The Wenzel article gives three circuit topologies. The third shows an opamp feeding a 2N4401 across 0.05 ohm in the power path. Sounds like what you are describing. Did you miss that one or are you describing something different? ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Low noise power supplies?
PTAT == Proportional To Absolute Temperature Dave ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Low noise power supplies?
Lester wrote: For a regulated power supply, make one using a 723. The 723 has far lower noise out than the monolithic regulators. If you are willing to design your own regulator using a 723, you may as well use a few more parts to get a much better result. Neither the internal reference nor the internal error amp in a 723 is anywhere near state of the art today with respect to noise, tempco, or speed. Using readily available buried zener references and low-noise, high-speed op amps (or even a few discrete transistors), you can do several orders of magnitude better than a 723 in all respects. The web is overflowing with designs (though not all of the circuits you find perform as advertised, so evaluate them with a critical eye and use your own sound judgment). But wasn't the original question what is available off-the-shelf? Best regards, Charles ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Low noise power supplies?
Am 31.01.2013 03:16, schrieb Richard (Rick) Karlquist: I know this topic has been discussed in the past on the list, but a colleague is asking if there are any off the shelf low noise power supplies for testing oscillators. Something The E5052B signal source analyzer has low noise power and control voltage supplies for just that purpose. E5052 are not that exotic any more. At a customer's I have seen 5 of them being sent on one day for calibration and that did not create any bottleneck. :-) regards, Gerhard ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Low noise power supplies?
Am 31.01.2013 05:28, schrieb Chris Albertson: For once the best is also cheap: Batteries. But not all batteries are the same. You want one with low internal resistance, so a lead acid flooded battery will be the best. Fred Walls Co have done tests on batteries. The article is somewhere on the NIST time/freq server. regards, Gerhard ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Low noise power supplies?
Hi To answer the original question - Power Design makes some pretty quiet bench supplies. If you are doing low noise testing, batteries often will let you get rid of one more ground loop. Even well built power supplies are not as well line isolated as a battery. Bob -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of Charles P. Steinmetz Sent: Thursday, January 31, 2013 5:33 AM To: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] Low noise power supplies? Lester wrote: For a regulated power supply, make one using a 723. The 723 has far lower noise out than the monolithic regulators. If you are willing to design your own regulator using a 723, you may as well use a few more parts to get a much better result. Neither the internal reference nor the internal error amp in a 723 is anywhere near state of the art today with respect to noise, tempco, or speed. Using readily available buried zener references and low-noise, high-speed op amps (or even a few discrete transistors), you can do several orders of magnitude better than a 723 in all respects. The web is overflowing with designs (though not all of the circuits you find perform as advertised, so evaluate them with a critical eye and use your own sound judgment). But wasn't the original question what is available off-the-shelf? Best regards, Charles ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Low noise power supplies?
If the main concern is about low-frequency noise the LT1763 might be worth considering for a simple solution, as it is capable of lower noise than the data sheet shows. With a bypass capacitor (Cbyp) fitted, the noise floor is ~30nV/rtHz. Although the data sheet only recommends up to 10nF for Cbyp, higher values continue to reduce the low-frequency noise. Correspondence with Linear Tech confirmed that it is OK to increase Cbyp as long as its leakage current is low enough and the output shunt capacitance is large enough. With Cbyp=22uF and metal film resistors used, the noise at 1Hz (with +10.6V output) came down to not much above 30nV/rtHz. The downside is that the output voltage rise time is a few minutes! (And if you short the output, it takes just as long for it to come back again.) Maybe not a problem for lab use. The LT1763 produces a noise peak around 150-200kHz if Cbyp is fitted (any value), but increasing the output capacitor to 100uF brings the peak down to ~30nV/rtHz. Garry Thorp ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Low noise power supplies?
Rick, the E3610A is really clean. If that isn't good enough, there are some audio-related circuits like the ALWSR. http://www.andrewweekes.talktalk.net/Manuals/ALWSR_rev2.9_Iss005s.pdf It's based on a Walt Jung design (Analog Devices). Here's the man himself with tons of valuable information about ultra low PS design: http://waltjung.org/Library.html Adrian Richard (Rick) Karlquist schrieb: I know this topic has been discussed in the past on the list, but a colleague is asking if there are any off the shelf low noise power supplies for testing oscillators. Something a cut above an HP brick lab power supply etc. They are hoping to avoid having to homebrew a power conditioning circuit. Did we ever arrive at a concensus as to the state of the art in homebrew power conditioning circuits? Any help would be appreciated. Rick Karlquist N6RK ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Low noise power supplies?
Hi Rick, I'll answer the question with anther question -- how does one properly measure power supply noise? Does it boil down to a single number, a couple of key numbers, or is it a plot, or several plots? I ask because without some sort of standard test and reporting method it just becomes a word game. Like, use batteries because they are better; use my design because it is quiet; this has lower noise than that. RMS AC ripple or nV/rtHz sounds like a good start, but I'm wondering if there's something more complete. I was never quite satisfied with the outcome of comparing a half dozen power supplies this way: http://www.leapsecond.com/pages/tbolt/noise.htm We have rigorous ways to compare and report oscillator performance; both as numbers and as plots. Is there something equivalent for power supplies? Thanks, /tvb I know this topic has been discussed in the past on the list, but a colleague is asking if there are any off the shelf low noise power supplies for testing oscillators. Something a cut above an HP brick lab power supply etc. They are hoping to avoid having to homebrew a power conditioning circuit. Did we ever arrive at a concensus as to the state of the art in homebrew power conditioning circuits? Any help would be appreciated. Rick Karlquist N6RK ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Low noise power supplies?
On 31 January 2013 04:28, Chris Albertson albertson.ch...@gmail.com wrote: On Wed, Jan 30, 2013 at 6:16 PM, Richard (Rick) Karlquist rich...@karlquist.com wrote: I know this topic has been discussed in the past on the list, but a colleague is asking if there are any off the shelf low noise power supplies for testing oscillators. Something a cut above an HP brick lab power supply etc. For once the best is also cheap: Batteries. My first thought was that a battery was best. Obviously batteries will have a long term drop in voltage as the battery gets more depleted, but is there any short term noise from a battery? There is going to be thermal noise, but I wonder if some types of batteries are better from a noise perspective than others? Perhaps a number of batteries having the same nomilal voltage, capacity and internal resistance are all equal, but perhaps some are more equal than others! Dave Dave ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Low noise power supplies?
Hi I think the comparison of PSD on a power supply to phase noise and phase noise plots is a pretty good one in this case. For most applications nV/sqrt(Hz) is a pretty good way to check things out on a supply or regulator. It's not quite the same thing as dbc / sqrt(Hz) but it conveys the same sort of information. Unless you have a *very* sensitive part, anything below 10 nV/ sqrt(Hz) is likely to be a very quiet supply. The main limit you hit is in the sub 100 Hz region where you likely see things like popcorn noise. AC ripple is no different than spurs in phase noise testing. You sometimes see people who ignore them when plotting phase noise. I'd suggest that they are an important part of characterizing a power supply. As with phase noise, frequency ranges are going to be application dependant. I may not care about 0.1 to 10 Hz phase noise for project A. It may be the only thing I care about for project B. Same thing with power supplies. With a good enough voltmeter you could carry the analogy one step further and compute an ADEV like number on the output voltage. I suspect that's carrying things a bit far. Bob -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of Tom Van Baak Sent: Thursday, January 31, 2013 9:43 AM To: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] Low noise power supplies? Hi Rick, I'll answer the question with anther question -- how does one properly measure power supply noise? Does it boil down to a single number, a couple of key numbers, or is it a plot, or several plots? I ask because without some sort of standard test and reporting method it just becomes a word game. Like, use batteries because they are better; use my design because it is quiet; this has lower noise than that. RMS AC ripple or nV/rtHz sounds like a good start, but I'm wondering if there's something more complete. I was never quite satisfied with the outcome of comparing a half dozen power supplies this way: http://www.leapsecond.com/pages/tbolt/noise.htm We have rigorous ways to compare and report oscillator performance; both as numbers and as plots. Is there something equivalent for power supplies? Thanks, /tvb I know this topic has been discussed in the past on the list, but a colleague is asking if there are any off the shelf low noise power supplies for testing oscillators. Something a cut above an HP brick lab power supply etc. They are hoping to avoid having to homebrew a power conditioning circuit. Did we ever arrive at a concensus as to the state of the art in homebrew power conditioning circuits? Any help would be appreciated. Rick Karlquist N6RK ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Low noise power supplies?
And this (very interesting) thread brings up the question of measurement methods. Some time ago I searched around and didn't find much on a standard way to measure noise on low voltage DC supplies. John On 1/31/2013 11:36 AM, Bob Camp wrote: Hi I think the comparison of PSD on a power supply to phase noise and phase noise plots is a pretty good one in this case. For most applications nV/sqrt(Hz) is a pretty good way to check things out on a supply or regulator. It's not quite the same thing as dbc / sqrt(Hz) but it conveys the same sort of information. Unless you have a *very* sensitive part, anything below 10 nV/ sqrt(Hz) is likely to be a very quiet supply. The main limit you hit is in the sub 100 Hz region where you likely see things like popcorn noise. AC ripple is no different than spurs in phase noise testing. You sometimes see people who ignore them when plotting phase noise. I'd suggest that they are an important part of characterizing a power supply. As with phase noise, frequency ranges are going to be application dependant. I may not care about 0.1 to 10 Hz phase noise for project A. It may be the only thing I care about for project B. Same thing with power supplies. With a good enough voltmeter you could carry the analogy one step further and compute an ADEV like number on the output voltage. I suspect that's carrying things a bit far. Bob -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of Tom Van Baak Sent: Thursday, January 31, 2013 9:43 AM To: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] Low noise power supplies? Hi Rick, I'll answer the question with anther question -- how does one properly measure power supply noise? Does it boil down to a single number, a couple of key numbers, or is it a plot, or several plots? I ask because without some sort of standard test and reporting method it just becomes a word game. Like, use batteries because they are better; use my design because it is quiet; this has lower noise than that. RMS AC ripple or nV/rtHz sounds like a good start, but I'm wondering if there's something more complete. I was never quite satisfied with the outcome of comparing a half dozen power supplies this way: http://www.leapsecond.com/pages/tbolt/noise.htm We have rigorous ways to compare and report oscillator performance; both as numbers and as plots. Is there something equivalent for power supplies? Thanks, /tvb I know this topic has been discussed in the past on the list, but a colleague is asking if there are any off the shelf low noise power supplies for testing oscillators. Something a cut above an HP brick lab power supply etc. They are hoping to avoid having to homebrew a power conditioning circuit. Did we ever arrive at a concensus as to the state of the art in homebrew power conditioning circuits? Any help would be appreciated. Rick Karlquist N6RK ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Low noise power supplies?
On 31.01.2013 09:05, Adrian wrote: Rick, the E3610A is really clean. The discussion is interesting, but the original question did ask about off the shelf so I have been watching for any mention of HP/Agilent precision power supplies. The E3610A specification says 200 uVrms, 2mv pp ripple and noise over the range 20Hz to 20 MHz. The now obsolete HP6114A spec is much better at 40uVrms, 100uV pp up to 20MHz. The 6114A is no longer available (except on eBay), but there should be something equivalent or better. I discovered the 6114A one day when I needed a nice stable voltage source to check some data acquisition equipment. My first pick was a gel-cel, but with a 34401 DMM you can watch those self-discharge. A regular bench supply kind of wanders around. But after a few minute warm-up the 6114A that I found sitting on a storage shelf was nice and stable. I mentioned the specification for noise because I have observed its stability, but have not made any measurements on its noise. Gary ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Low noise power supplies?
Hi A very common way to check one is to use the HP 3561 off of the old 3048 phase noise test set. With a simple op amp based preamp you can easily get down below 3 nv / sqrt(Hz). With more exotic amps you can get well below that. Volts over a bandwidth really don't tell the story very well. In the popcorn noise region, you don't have much choice. Once you get past that PSD is very much the right way to go. For some numbers once you are out of the popcorn / flicker noise region: 1 nV / sqrt(Hz) = about as quiet as it's worth getting ever. 10 nV / sqrt(Hz) = good enough for anything you are likely to be doing 100 nV / sqrt(Hz) = noisy enough to begin to bother you in some cases 1uV / sqrt(Hz) = pretty awful. As always, it really depends on what you are doing. A microprocessor will not be bothered much at all by a relatively noisy supply. Bob -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of Burt I. Weiner Sent: Thursday, January 31, 2013 12:08 PM To: time-nuts@febo.com Subject: [time-nuts] Low noise power supplies? Gang, I'm following this thread with great interest, but, just for my own reference, what is considered low power supply noise? Can you give me some numbers and over what bandwidth? Thanks, Burt, K6OQK time-nuts@febo.com Subject: Re: [time-nuts] Low noise power supplies? Hi To answer the original question - Power Design makes some pretty quiet bench supplies. If you are doing low noise testing, batteries often will let you get rid of one more ground loop. Even well built power supplies are not as well line isolated as a battery. Bob Burt I. Weiner Associates Broadcast Technical Services Glendale, California U.S.A. b...@att.net www.biwa.cc K6OQK ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Low noise power supplies?
On 31 January 2013 17:11, John Ackermann N8UR j...@febo.com wrote: And this (very interesting) thread brings up the question of measurement methods. Some time ago I searched around and didn't find much on a standard way to measure noise on low voltage DC supplies. John Did you try the volt-nuts mailing list? Dave ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Low noise power supplies?
A non-standard but repeatable way to measure power supply noise is to use a Transmission Impairment Measuring Set (TIMS) such as the HP3945(6)A or 3551 (2)A. These were intended for use in pairs to assess analog telephone lines for data use. As well as an AF generator, frequency counter, amplifier, monitor speaker and level meter they will measure broadband noise. Being designed for POTS they will also withstand at least 50V DC at the input while measuring the noise. You can also apply internal filters if required. The last digit designates a North American (BELL) or European (CCITT) standard unit, but broadband noise is the same. They can be picked up really cheaply now (list was$3000-$5000) and make a nice compact audio test set. Robert G8RPI. From: Bob Camp li...@rtty.us To: 'Discussion of precise time and frequency measurement' time-nuts@febo.com Sent: Thursday, 31 January 2013, 18:02 Subject: Re: [time-nuts] Low noise power supplies? Hi A very common way to check one is to use the HP 3561 off of the old 3048 phase noise test set. With a simple op amp based preamp you can easily get down below 3 nv / sqrt(Hz). With more exotic amps you can get well below that. Volts over a bandwidth really don't tell the story very well. In the popcorn noise region, you don't have much choice. Once you get past that PSD is very much the right way to go. For some numbers once you are out of the popcorn / flicker noise region: 1 nV / sqrt(Hz) = about as quiet as it's worth getting ever. 10 nV / sqrt(Hz) = good enough for anything you are likely to be doing 100 nV / sqrt(Hz) = noisy enough to begin to bother you in some cases 1uV / sqrt(Hz) = pretty awful. As always, it really depends on what you are doing. A microprocessor will not be bothered much at all by a relatively noisy supply. Bob -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of Burt I. Weiner Sent: Thursday, January 31, 2013 12:08 PM To: time-nuts@febo.com Subject: [time-nuts] Low noise power supplies? Gang, I'm following this thread with great interest, but, just for my own reference, what is considered low power supply noise? Can you give me some numbers and over what bandwidth? Thanks, Burt, K6OQK time-nuts@febo.com Subject: Re: [time-nuts] Low noise power supplies? Hi To answer the original question - Power Design makes some pretty quiet bench supplies. If you are doing low noise testing, batteries often will let you get rid of one more ground loop. Even well built power supplies are not as well line isolated as a battery. Bob Burt I. Weiner Associates Broadcast Technical Services Glendale, California U.S.A. b...@att.net www.biwa.cc K6OQK ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Low noise power supplies?
Oops, that should be HP4945(6)A not 3945 Robert. From: Robert Atkinson robert8...@yahoo.co.uk To: Discussion of precise time and frequency measurement time-nuts@febo.com Sent: Thursday, 31 January 2013, 18:46 Subject: Re: [time-nuts] Low noise power supplies? A non-standard but repeatable way to measure power supply noise is to use a Transmission Impairment Measuring Set (TIMS) such as the HP3945(6)A or 3551 (2)A. These were intended for use in pairs to assess analog telephone lines for data use. As well as an AF generator, frequency counter, amplifier, monitor speaker and level meter they will measure broadband noise. Being designed for POTS they will also withstand at least 50V DC at the input while measuring the noise. You can also apply internal filters if required. The last digit designates a North American (BELL) or European (CCITT) standard unit, but broadband noise is the same. They can be picked up really cheaply now (list was$3000-$5000) and make a nice compact audio test set. Robert G8RPI. From: Bob Camp li...@rtty.us To: 'Discussion of precise time and frequency measurement' time-nuts@febo.com Sent: Thursday, 31 January 2013, 18:02 Subject: Re: [time-nuts] Low noise power supplies? Hi A very common way to check one is to use the HP 3561 off of the old 3048 phase noise test set. With a simple op amp based preamp you can easily get down below 3 nv / sqrt(Hz). With more exotic amps you can get well below that. Volts over a bandwidth really don't tell the story very well. In the popcorn noise region, you don't have much choice. Once you get past that PSD is very much the right way to go. For some numbers once you are out of the popcorn / flicker noise region: 1 nV / sqrt(Hz) = about as quiet as it's worth getting ever. 10 nV / sqrt(Hz) = good enough for anything you are likely to be doing 100 nV / sqrt(Hz) = noisy enough to begin to bother you in some cases 1uV / sqrt(Hz) = pretty awful. As always, it really depends on what you are doing. A microprocessor will not be bothered much at all by a relatively noisy supply. Bob -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of Burt I. Weiner Sent: Thursday, January 31, 2013 12:08 PM To: time-nuts@febo.com Subject: [time-nuts] Low noise power supplies? Gang, I'm following this thread with great interest, but, just for my own reference, what is considered low power supply noise? Can you give me some numbers and over what bandwidth? Thanks, Burt, K6OQK time-nuts@febo.com Subject: Re: [time-nuts] Low noise power supplies? Hi To answer the original question - Power Design makes some pretty quiet bench supplies. If you are doing low noise testing, batteries often will let you get rid of one more ground loop. Even well built power supplies are not as well line isolated as a battery. Bob Burt I. Weiner Associates Broadcast Technical Services Glendale, California U.S.A. b...@att.net www.biwa.cc K6OQK ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Low noise power supplies?
Not sure if anyone posted this here yet, but Abracom has a very low noise (7nV/RtHz at 1KHz) power source for VCO's etc, with various outputs. It's sold on DIgikey or Mouser I think. Here is a review of that unit: _http://jaunty-electronics.com/blog/category/reviews/_ (http://jaunty-electronics.com/blog/category/reviews/) Co-incidentally he also has a review of one of our units on the same page. This is a very handy and reasonably priced power supply for many low-noise type of experiments. bye, Said In a message dated 1/30/2013 21:36:50 Pacific Standard Time, bruce.griffi...@xtra.co.nz writes: Lester Veenstra wrote: The typical test supply on a bench for clean VCO testing is a small gel cell battery. For a regulated power supply, make one using a 723. The 723 has far lower noise out than the monolithic regulators. Depends on the variety of 723 some are noisier than others. Some use an internal zener reference, some use a bandgap reference. The original used a zener reference. Bruce Lester B Veenstra MØYCM K1YCM W8YCM les...@veenstras.com US Postal Address: 5 Shrine Club Drive HC84 Box 89C Keyser WV 26726 GPS: 39.33675 N 78.9823527 W Telephones: Home:+1-304-289-6057 US cell +1-304-790-9192 UK cell +44-(0)7849-248-749 Guam Cell: +1-671-929-8141 Jamaica: +1-876-456-8898 This e-mail and any documents attached hereto contain confidential or privileged information. The information is intended to be for use only by the individual or entity to whom they are addressed. If you are not the intended recipient or the person responsible for delivering the e-mail to the intended recipient, be aware that any disclosure, copying, distribution or use of the contents of this e-mail or any documents attached hereto is prohibited. -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of Richard (Rick) Karlquist Sent: Wednesday, January 30, 2013 9:17 PM To: Discussion of precise time and frequency measurement Subject: [time-nuts] Low noise power supplies? I know this topic has been discussed in the past on the list, but a colleague is asking if there are any off the shelf low noise power supplies for testing oscillators. Something a cut above an HP brick lab power supply etc. They are hoping to avoid having to homebrew a power conditioning circuit. Did we ever arrive at a concensus as to the state of the art in homebrew power conditioning circuits? Any help would be appreciated. Rick Karlquist N6RK ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Low noise power supplies?
Hi For $393.75 does it come with a wall wart? If not I would definitely go for a medical ground isolated / low leakage version to power the beast. The added cost over a plain jane wall wart won't add much to the purchase price percentage wise. Bob -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of saidj...@aol.com Sent: Thursday, January 31, 2013 3:58 PM To: time-nuts@febo.com; les...@veenstras.com Subject: Re: [time-nuts] Low noise power supplies? Not sure if anyone posted this here yet, but Abracom has a very low noise (7nV/RtHz at 1KHz) power source for VCO's etc, with various outputs. It's sold on DIgikey or Mouser I think. Here is a review of that unit: _http://jaunty-electronics.com/blog/category/reviews/_ (http://jaunty-electronics.com/blog/category/reviews/) Co-incidentally he also has a review of one of our units on the same page. This is a very handy and reasonably priced power supply for many low-noise type of experiments. bye, Said In a message dated 1/30/2013 21:36:50 Pacific Standard Time, bruce.griffi...@xtra.co.nz writes: Lester Veenstra wrote: The typical test supply on a bench for clean VCO testing is a small gel cell battery. For a regulated power supply, make one using a 723. The 723 has far lower noise out than the monolithic regulators. Depends on the variety of 723 some are noisier than others. Some use an internal zener reference, some use a bandgap reference. The original used a zener reference. Bruce Lester B Veenstra MØYCM K1YCM W8YCM les...@veenstras.com US Postal Address: 5 Shrine Club Drive HC84 Box 89C Keyser WV 26726 GPS: 39.33675 N 78.9823527 W Telephones: Home:+1-304-289-6057 US cell +1-304-790-9192 UK cell +44-(0)7849-248-749 Guam Cell: +1-671-929-8141 Jamaica: +1-876-456-8898 This e-mail and any documents attached hereto contain confidential or privileged information. The information is intended to be for use only by the individual or entity to whom they are addressed. If you are not the intended recipient or the person responsible for delivering the e-mail to the intended recipient, be aware that any disclosure, copying, distribution or use of the contents of this e-mail or any documents attached hereto is prohibited. -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of Richard (Rick) Karlquist Sent: Wednesday, January 30, 2013 9:17 PM To: Discussion of precise time and frequency measurement Subject: [time-nuts] Low noise power supplies? I know this topic has been discussed in the past on the list, but a colleague is asking if there are any off the shelf low noise power supplies for testing oscillators. Something a cut above an HP brick lab power supply etc. They are hoping to avoid having to homebrew a power conditioning circuit. Did we ever arrive at a concensus as to the state of the art in homebrew power conditioning circuits? Any help would be appreciated. Rick Karlquist N6RK ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Low noise power supplies?
There are at least two methods. First, the broadband or time domain method that uses a low noise amplifier and oscilloscope, and specifies noise voltage within a certain bandwidth. For details check application notes from LTC and Analog Devices. The narrowband or frequency domain method specifies noise voltage within a normalized bandwidth (nV/sqrt(Hz)) at a specific frequency. A typical test setup is included in the HP 3048A phase noise measurement system as so-called base-band noise measurement. For higher noise voltages, the 3561A dynamic signal analyzer alone is used with a DC blocking capacitor. For lower noise voltages, the signal is first amplified by the LNA that is part of the 11848A phase noise test set. For details please see the HP 3048A manual that can be downloaded from http://www.hparchive.com/hp_equipment.htm Note the Opt K23 DC blocking filter. There is an insertion loss of 6 dB to be entered in the 3048A software when using the DC block in conjunction with the 11848A. Obviously, any FFT analyzer plus LNA and coupling cap can be used for that method. The major advantage of the 3048A system is the automatic generation of plots. Adrian John Ackermann N8UR schrieb: And this (very interesting) thread brings up the question of measurement methods. Some time ago I searched around and didn't find much on a standard way to measure noise on low voltage DC supplies. John On 1/31/2013 11:36 AM, Bob Camp wrote: Hi I think the comparison of PSD on a power supply to phase noise and phase noise plots is a pretty good one in this case. For most applications nV/sqrt(Hz) is a pretty good way to check things out on a supply or regulator. It's not quite the same thing as dbc / sqrt(Hz) but it conveys the same sort of information. Unless you have a *very* sensitive part, anything below 10 nV/ sqrt(Hz) is likely to be a very quiet supply. The main limit you hit is in the sub 100 Hz region where you likely see things like popcorn noise. AC ripple is no different than spurs in phase noise testing. You sometimes see people who ignore them when plotting phase noise. I'd suggest that they are an important part of characterizing a power supply. As with phase noise, frequency ranges are going to be application dependant. I may not care about 0.1 to 10 Hz phase noise for project A. It may be the only thing I care about for project B. Same thing with power supplies. With a good enough voltmeter you could carry the analogy one step further and compute an ADEV like number on the output voltage. I suspect that's carrying things a bit far. Bob -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of Tom Van Baak Sent: Thursday, January 31, 2013 9:43 AM To: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] Low noise power supplies? Hi Rick, I'll answer the question with anther question -- how does one properly measure power supply noise? Does it boil down to a single number, a couple of key numbers, or is it a plot, or several plots? I ask because without some sort of standard test and reporting method it just becomes a word game. Like, use batteries because they are better; use my design because it is quiet; this has lower noise than that. RMS AC ripple or nV/rtHz sounds like a good start, but I'm wondering if there's something more complete. I was never quite satisfied with the outcome of comparing a half dozen power supplies this way: http://www.leapsecond.com/pages/tbolt/noise.htm We have rigorous ways to compare and report oscillator performance; both as numbers and as plots. Is there something equivalent for power supplies? Thanks, /tvb I know this topic has been discussed in the past on the list, but a colleague is asking if there are any off the shelf low noise power supplies for testing oscillators. Something a cut above an HP brick lab power supply etc. They are hoping to avoid having to homebrew a power conditioning circuit. Did we ever arrive at a concensus as to the state of the art in homebrew power conditioning circuits? Any help would be appreciated. Rick Karlquist N6RK ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time
Re: [time-nuts] Low noise power supplies?
Content-Type: text/plain; charset=ISO-8859-1 In message C7259FFFCD3E42C2815B939BA386A0A8@pc52, Tom Van Baak writes: We have rigorous ways to compare and report oscillator performance; both as numbers and as plots. Is there something equivalent for power supplies? Phase Noise measured on a 0Hz carrier ? If you want the dynamic behaviour, it gets much more tricky, because then you have both the spectrum of the load-changes and the supply-changes, resulting in a spectrum output from the PSU. -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 p...@freebsd.org | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Low noise power supplies?
tvb wrote: I'll answer the question with anther question -- how does one properly measure power supply noise? Does it boil down to a single number, a couple of key numbers, or is it a plot, or several plots? There are a number of standard ways, some of which have been mentioned by others, none of which is all that helpful IMO. What I find most useful is a plot of noise density vs. frequency from, say, 0.1 Hz to as high as you require. The data should be taken and processed with sufficient frequency resolution to show any spurs in the band of interest. It is often helpful to have several plots, each covering part of the band of interest, to improve the displayed resolution of spurs. NOTE: Designing a preamp for collecting the data is far from trivial. Articles have been written about it (see, for example, Linear Technology Application Note 124 by Jim Williams www.linear.com/docs/28585). Best regards, Charles ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Low noise power supplies?
Charles, thanks for posting. That is the LTC application note I had in mind. And here is Bruce's contribution to low noise PS design and measurement: http://www.ko4bb.com/~bruce/LowNoisePowerSupplies.html Don't miss to scroll fully down. There is a link to an IEEE paper discussing chemical battery noise measurement. Adrian Charles P. Steinmetz schrieb: tvb wrote: I'll answer the question with anther question -- how does one properly measure power supply noise? Does it boil down to a single number, a couple of key numbers, or is it a plot, or several plots? There are a number of standard ways, some of which have been mentioned by others, none of which is all that helpful IMO. What I find most useful is a plot of noise density vs. frequency from, say, 0.1 Hz to as high as you require. The data should be taken and processed with sufficient frequency resolution to show any spurs in the band of interest. It is often helpful to have several plots, each covering part of the band of interest, to improve the displayed resolution of spurs. NOTE: Designing a preamp for collecting the data is far from trivial. Articles have been written about it (see, for example, Linear Technology Application Note 124 by Jim Williams www.linear.com/docs/28585). Best regards, Charles ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Low noise power supplies?
Or a good battery as a source for the regulators as discussed in this thread already. It's quite nice to have all the different Voltages available at the same time, with up to 200mA. bye, Said In a message dated 1/31/2013 13:12:33 Pacific Standard Time, li...@rtty.us writes: Hi For $393.75 does it come with a wall wart? If not I would definitely go for a medical ground isolated / low leakage version to power the beast. The added cost over a plain jane wall wart won't add much to the purchase price percentage wise. Bob -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of saidj...@aol.com Sent: Thursday, January 31, 2013 3:58 PM To: time-nuts@febo.com; les...@veenstras.com Subject: Re: [time-nuts] Low noise power supplies? Not sure if anyone posted this here yet, but Abracom has a very low noise (7nV/RtHz at 1KHz) power source for VCO's etc, with various outputs. It's sold on DIgikey or Mouser I think. Here is a review of that unit: _http://jaunty-electronics.com/blog/category/reviews/_ (http://jaunty-electronics.com/blog/category/reviews/) Co-incidentally he also has a review of one of our units on the same page. This is a very handy and reasonably priced power supply for many low-noise type of experiments. bye, Said In a message dated 1/30/2013 21:36:50 Pacific Standard Time, bruce.griffi...@xtra.co.nz writes: Lester Veenstra wrote: The typical test supply on a bench for clean VCO testing is a small gel cell battery. For a regulated power supply, make one using a 723. The 723 has far lower noise out than the monolithic regulators. Depends on the variety of 723 some are noisier than others. Some use an internal zener reference, some use a bandgap reference. The original used a zener reference. Bruce Lester B Veenstra MØYCM K1YCM W8YCM les...@veenstras.com US Postal Address: 5 Shrine Club Drive HC84 Box 89C Keyser WV 26726 GPS: 39.33675 N 78.9823527 W Telephones: Home:+1-304-289-6057 US cell +1-304-790-9192 UK cell +44-(0)7849-248-749 Guam Cell: +1-671-929-8141 Jamaica: +1-876-456-8898 This e-mail and any documents attached hereto contain confidential or privileged information. The information is intended to be for use only by the individual or entity to whom they are addressed. If you are not the intended recipient or the person responsible for delivering the e-mail to the intended recipient, be aware that any disclosure, copying, distribution or use of the contents of this e-mail or any documents attached hereto is prohibited. -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of Richard (Rick) Karlquist Sent: Wednesday, January 30, 2013 9:17 PM To: Discussion of precise time and frequency measurement Subject: [time-nuts] Low noise power supplies? I know this topic has been discussed in the past on the list, but a colleague is asking if there are any off the shelf low noise power supplies for testing oscillators. Something a cut above an HP brick lab power supply etc. They are hoping to avoid having to homebrew a power conditioning circuit. Did we ever arrive at a concensus as to the state of the art in homebrew power conditioning circuits? Any help would be appreciated. Rick Karlquist N6RK ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Low noise power supplies?
Hi If you are driving a spectrum analyzer, the 10,000X mentioned in the app note simply is not needed. A gain of 10X or less will get you to below 2 nv / sqrt(Hz) at 100 Hz and beyond. A 10 Hz blocking cap does not need to be a 24 hours to stabilize device. An AD 797, a couple of metal film resistors, and a fairly large (say 47 uf) plastic cap work pretty well. Bob On Jan 31, 2013, at 7:20 PM, Charles P. Steinmetz charles_steinm...@lavabit.com wrote: tvb wrote: I'll answer the question with anther question -- how does one properly measure power supply noise? Does it boil down to a single number, a couple of key numbers, or is it a plot, or several plots? There are a number of standard ways, some of which have been mentioned by others, none of which is all that helpful IMO. What I find most useful is a plot of noise density vs. frequency from, say, 0.1 Hz to as high as you require. The data should be taken and processed with sufficient frequency resolution to show any spurs in the band of interest. It is often helpful to have several plots, each covering part of the band of interest, to improve the displayed resolution of spurs. NOTE: Designing a preamp for collecting the data is far from trivial. Articles have been written about it (see, for example, Linear Technology Application Note 124 by Jim Williams www.linear.com/docs/28585). Best regards, Charles ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Low noise power supplies?
Bob wrote: An AD 797, a couple of metal film resistors, and a fairly large (say 47 uf) plastic cap work pretty well. The band from 10 Hz down to 0.1 or 0.01 Hz is generally important when testing oscillators. To keep the 797 input noise density below a few nV per root Hz, the terminations must have very low resistance. With such low resistance, a 47 uF cap won't even get you to 10 Hz, much less 0.1 or 0.01 Hz. One more thought: Many oscillators have internal regulators that are not nearly as good as what you can build. No sense using an external supply with 5 nV per root Hz noise density if it will be re-regulated inside the oscillator by a circuit that has a noise density of 250 nV per root Hz. Best regards, Charles ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Low noise power supplies?
One more thought: Many oscillators have internal regulators that are not nearly as good as what you can build. No sense using an external supply with 5 nV per root Hz noise density if it will be re-regulated inside the oscillator by a circuit that has a noise density of 250 nV per root Hz. Best regards, Charles Good point. Just to clarify my original request, my colleagues are currently using batteries, and they don't have internal regulators. Their problem is not that the batteries don't work, but they want to travel around and give demos and the batteries obviously are a PITA. BTW, one of papers cited had a reference to Fred Walls paper on battery noise. Fred knocks it out the park as usual. He was like a rock star at FCS in those days. A rare example of government productivity. Rick Karlquist N6RK ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Low noise power supplies?
You haven't seen it used because it doesn't work very well. It appeared in a few pieces of Heathkit equipment but I don't think HP or Tek used it at all. Any AC component of base to collector voltage has a small but definite effect on Vbe which transfers voltage in the reverse direction from collector to emitter even though the base is held at AC ground. A three terminal regulator does a better job of suppressing ripple from a power supply. Regulators use a zener diode as the reference and there are circuits in which a zener is used as a noise source. What does that tell you? The quietest power supply is an analog regulator followed by one or more RC filter sections. The inductor in an LC filter is likely to pick up more hum and noise than it filters out. My presumption is that a low noise power supply is likely to be providing a small amount of power to the load and load regulation is probably not a problem. Regards. Max. K 4 O DS. Email: m...@maxsmusicplace.com Transistor site http://www.funwithtransistors.net Vacuum tube site: http://www.funwithtubes.net Woodworking site http://www.angelfire.com/electronic/funwithtubes/Woodworking/wwindex.html Music site: http://www.maxsmusicplace.com To subscribe to the fun with transistors group send an email to. funwithtransistors-subscr...@yahoogroups.com To subscribe to the fun with tubes group send an email to, funwithtubes-subscr...@yahoogroups.com To subscribe to the fun with wood group send a blank email to funwithwood-subscr...@yahoogroups.com - Original Message - From: Joe Leikhim jleik...@leikhim.com To: time-nuts@febo.com Sent: Thursday, January 31, 2013 2:39 PM Subject: [time-nuts] Low noise power supplies? Back when I was in product engineering there was a VCO design that used a superfilter circuit. It consisted of a pass transistor and a filter cap from base to ground. The gain of the transistor multiplied the effective capacitance. I have not seen this configuration since. -- Joe Leikhim Leikhim and Associates Communications Consultants Oviedo, Florida jleik...@leikhim.com 407-982-0446 WWW.LEIKHIM.COM ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Low noise power supplies?
I have seen it used in a couple of Tektronix TM500 instruments but the purpose may have been to generate a lower voltage power supply rail instead of noise reduction. Tektronix often added LC sections on their switching power supply outputs and distributed smaller LC sections to prevent coupling between different circuits. On Thu, 31 Jan 2013 22:12:42 -0600, Max Robinson m...@maxsmusicplace.com wrote: You haven't seen it used because it doesn't work very well. It appeared in a few pieces of Heathkit equipment but I don't think HP or Tek used it at all. Any AC component of base to collector voltage has a small but definite effect on Vbe which transfers voltage in the reverse direction from collector to emitter even though the base is held at AC ground. A three terminal regulator does a better job of suppressing ripple from a power supply. Regulators use a zener diode as the reference and there are circuits in which a zener is used as a noise source. What does that tell you? The quietest power supply is an analog regulator followed by one or more RC filter sections. The inductor in an LC filter is likely to pick up more hum and noise than it filters out. My presumption is that a low noise power supply is likely to be providing a small amount of power to the load and load regulation is probably not a problem. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Low noise power supplies?
Are 4 and 5 regulated? Or is the zener picked to compensate for the VBE drops? Any of these circuits where the output transistor is in an emitter follower configuration will have its noise effected by the load current, since that current directly effects the output transistor transconductance. On 1/31/2013 10:03 PM, John Miles wrote: Awhile back I ran some baseband plots of various supplies with an HP 3048A (image attached). In my experience measuring actual OCXOs, an LM317T or LM338K is quiet enough to avoid influencing oscillator PN. With these variable-voltage parts, you can bypass the reference pin for some additional improvement, but I don't believe I did that for these plots. It's easy to spot the difference between a 7812/7815 and an LM317T (see red versus green/white traces). As a lazy approach, try measuring the oscillator with both a 78XX and an LM317T. Because the 78XX is about 10 dB noisier across most of the spectrum, If you don't see a difference, you can assume that further optimization is pointless. Near 1 Hz this call may be questionable. If you don't need an LDO, don't use one. If you do, use the quietest part you can find. The best LDOs seem to be about as quiet as an ordinary LM317T. I've mentioned before that you need to be careful with large LC filters downstream of the regulator. A good power source will exhibit a low impedance at ALL offsets of interest. You sometimes see NIST circuits where the power is conditioned by a Darlington emitter follower whose base is fed with an RC-filtered Zener diode. The purple and orange traces are pretty informative with regard to that approach. On the orange trace, where the only filtering is the RC network between the Zener and the base, notice how the noise becomes worse than all of the other sources below 10 Hz. Here, the RC filter on the Zener becomes less effective and the Darlington pair obligingly amplifies the diode noise. An additional LC filter after the regulator may have the effect of herding the entire noise spectrum into a high-Q peak, even though the LC corner frequency is much higher than the RC filter in the base circuit (violet trace). Depending on your OCXO's supply rejection characteristics this could be a good thing or a bad thing. Finally, make sure the OCXO has good RF bypassing where its power supply pin enters the case. If in doubt, solder a 0.1 uF ceramic right at the point of entry. I've seen $2000 Wenzels that didn't bother doing this. I'm sure they looked good in a screen room. -- john Miles Design LLC -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts- boun...@febo.com] On Behalf Of Richard (Rick) Karlquist Sent: Wednesday, January 30, 2013 6:17 PM To: Discussion of precise time and frequency measurement Subject: [time-nuts] Low noise power supplies? I know this topic has been discussed in the past on the list, but a colleague is asking if there are any off the shelf low noise power supplies for testing oscillators. Something a cut above an HP brick lab power supply etc. They are hoping to avoid having to homebrew a power conditioning circuit. Did we ever arrive at a concensus as to the state of the art in homebrew power conditioning circuits? Any help would be appreciated. Rick Karlquist N6RK ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi- bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Low noise power supplies?
The typical test supply on a bench for clean VCO testing is a small gel cell battery. For a regulated power supply, make one using a 723. The 723 has far lower noise out than the monolithic regulators. Lester B Veenstra MØYCM K1YCM W8YCM les...@veenstras.com US Postal Address: 5 Shrine Club Drive HC84 Box 89C Keyser WV 26726 GPS: 39.33675 N 78.9823527 W Telephones: Home: +1-304-289-6057 US cell +1-304-790-9192 UK cell +44-(0)7849-248-749 Guam Cell: +1-671-929-8141 Jamaica: +1-876-456-8898 This e-mail and any documents attached hereto contain confidential or privileged information. The information is intended to be for use only by the individual or entity to whom they are addressed. If you are not the intended recipient or the person responsible for delivering the e-mail to the intended recipient, be aware that any disclosure, copying, distribution or use of the contents of this e-mail or any documents attached hereto is prohibited. -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of Richard (Rick) Karlquist Sent: Wednesday, January 30, 2013 9:17 PM To: Discussion of precise time and frequency measurement Subject: [time-nuts] Low noise power supplies? I know this topic has been discussed in the past on the list, but a colleague is asking if there are any off the shelf low noise power supplies for testing oscillators. Something a cut above an HP brick lab power supply etc. They are hoping to avoid having to homebrew a power conditioning circuit. Did we ever arrive at a concensus as to the state of the art in homebrew power conditioning circuits? Any help would be appreciated. Rick Karlquist N6RK ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Low noise power supplies?
On Wed, Jan 30, 2013 at 6:16 PM, Richard (Rick) Karlquist rich...@karlquist.com wrote: I know this topic has been discussed in the past on the list, but a colleague is asking if there are any off the shelf low noise power supplies for testing oscillators. Something a cut above an HP brick lab power supply etc. For once the best is also cheap: Batteries. But not all batteries are the same. You want one with low internal resistance, so a lead acid flooded battery will be the best. Chris Albertson Redondo Beach, California ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Low noise power supplies?
On 1/30/13 8:28 PM, Chris Albertson wrote: For once the best is also cheap: Batteries. But not all batteries are the same. You want one with low internal resistance, so a lead acid flooded battery will be the best. Most NiCd have very low internal resistance.. much lower than lead acid. But aside from batteries, Rick's question is interesting, and I'd turn it around a bit.. What off the shelf catalog product has the lowest noise? Do you go get a linear regulated supply from someone like Acopian? And even more interesting.. if you're concerned about efficiency and want to use a DC/DC switcher to convert some ratty DC supply (12V vehicle power, or a solar panel, for instance) to something really quiet, what's the best strategy, using off the shelf bricks and modules. That is, I'm sure someone could do a fabulous job with a box full of Ls and Cs and discrete components and a couple months to design, prototype, and build.. but if someone came to you and said, we want a mobile microwave system to study propagation in 3 weeks because they just got permission to go up on some mountain. Something like a CW carrier at tens of GHz multiplied up from your very quiet oscillator, and they're going to look at turbulence and scintillation in the path, so time scales of milliseconds to 1000s of seconds are important. What would you order from Newark, Allied, mouser, etc. (assuming you have your OCXOs and such sitting around). ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Low noise power supplies?
On Wed, Jan 30, 2013 at 9:05 PM, Jim Lux jim...@earthlink.net wrote: On 1/30/13 8:28 PM, Chris Albertson wrote: For once the best is also cheap: Batteries. But not all batteries are the same. You want one with low internal resistance, so a lead acid flooded battery will be the best. Most NiCd have very low internal resistance.. much lower than lead acid Really? I'm talking about flooded cells not gel. I think large automotive engine start battery might only have 20 milliohms resistance. But the only NiCd I know about are the AA sized ones. Not fair to compare. Perhaps a size size NiCd would be even better. I don't know. Got a reference, Google did not turn up much. I'd expect that some place there might be a table. I've powered resonably large transmitters with a bank of golf cart batteries. Not because I needed the low noise but because this was on a sail boat in the ocean. Chris Albertson Redondo Beach, California ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Low noise power supplies?
Lester Veenstra wrote: The typical test supply on a bench for clean VCO testing is a small gel cell battery. For a regulated power supply, make one using a 723. The 723 has far lower noise out than the monolithic regulators. Depends on the variety of 723 some are noisier than others. Some use an internal zener reference, some use a bandgap reference. The original used a zener reference. Bruce Lester B Veenstra MØYCM K1YCM W8YCM les...@veenstras.com US Postal Address: 5 Shrine Club Drive HC84 Box 89C Keyser WV 26726 GPS: 39.33675 N 78.9823527 W Telephones: Home: +1-304-289-6057 US cell+1-304-790-9192 UK cell+44-(0)7849-248-749 Guam Cell: +1-671-929-8141 Jamaica: +1-876-456-8898 This e-mail and any documents attached hereto contain confidential or privileged information. The information is intended to be for use only by the individual or entity to whom they are addressed. If you are not the intended recipient or the person responsible for delivering the e-mail to the intended recipient, be aware that any disclosure, copying, distribution or use of the contents of this e-mail or any documents attached hereto is prohibited. -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of Richard (Rick) Karlquist Sent: Wednesday, January 30, 2013 9:17 PM To: Discussion of precise time and frequency measurement Subject: [time-nuts] Low noise power supplies? I know this topic has been discussed in the past on the list, but a colleague is asking if there are any off the shelf low noise power supplies for testing oscillators. Something a cut above an HP brick lab power supply etc. They are hoping to avoid having to homebrew a power conditioning circuit. Did we ever arrive at a concensus as to the state of the art in homebrew power conditioning circuits? Any help would be appreciated. Rick Karlquist N6RK ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Low noise power supplies?
YUP, The C-130 aircraft uses larger than car battery size wet NiCd to fire up the Genset that is used to start the Tubo-prop jet engines. Definitely has lower resistance then the Lead-Acid wet cell. BillWB6BNQ Arthur Dent wrote: But the only NiCd I know about are the AA sized ones. I have some of the wet NiCd batteries that are capable of putting out 200A continuously. I'm assuming the internal resistance is pretty low. ;-) Arthur ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Low noise power supplies?
Hi Rick; Starting with a hp supply this finesse regulator will really clean up the output. http://www.wenzel.com/documents/finesse.html Best Wishes; Thomas Knox Date: Wed, 30 Jan 2013 18:16:46 -0800 From: rich...@karlquist.com To: time-nuts@febo.com Subject: [time-nuts] Low noise power supplies? I know this topic has been discussed in the past on the list, but a colleague is asking if there are any off the shelf low noise power supplies for testing oscillators. Something a cut above an HP brick lab power supply etc. They are hoping to avoid having to homebrew a power conditioning circuit. Did we ever arrive at a concensus as to the state of the art in homebrew power conditioning circuits? Any help would be appreciated. Rick Karlquist N6RK ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Low noise power supplies - dont' use Electrolytics
Ceramic caps can be microphonic. Just something to be on the look out. Not so much with leaded ceramics, but more of a problem with surface mounts. Tantalums are prone to overvoltage failure. Best to really overspec them regarding voltage. Note that some LDOs are not stable with really low ESR bypass. There are app notes on this. I've stated my preference for p-fet pass devices, or better yet, shunt regulators. The PNP pass devices will need feedforward compensation if the ESR is too low. On 11/27/2011 11:21 PM, Attila Kinali wrote: On Fri, 25 Nov 2011 22:25:37 -0800 Chris Albertsonalbertson.ch...@gmail.com wrote: One question: How does one avoid using electrolytic caps if you need (say) 1,000uF or even 100uF. Those would be some mighty big film caps. I think, aluminium electrolytics are meant, as these have a lot of wear and can die. Hence, you can use tantal or niob electrolytics, which have a dry eletrolyt. Or you can use ceramics which are already available at 100uF. Attila Kinali ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Low noise power supplies - dont' use Electrolytics
On Mon, 28 Nov 2011 01:05:22 -0800 gary li...@lazygranch.com wrote: Ceramic caps can be microphonic. Just something to be on the look out. Not so much with leaded ceramics, but more of a problem with surface mounts. Ceramic caps have a lot of other problems too, like capacitance derating on increasing voltage. Some types go down to 80% of rated capacity when driven to the max rated voltage. Tantalums are prone to overvoltage failure. Best to really overspec them regarding voltage. Uhmm.. overspec? The rated voltage is the maximum allowed voltage. Like something you should never cross. That's why we have these odd numbers like 16V. They are not intended to be used at 16V but rather at standard voltages like 12V. Note that some LDOs are not stable with really low ESR bypass. There are app notes on this. Actually, the datasheet of any LDO (or power regulator) should define the stable operation output capacitance and ESR. If you work outside the speced range.. well.. your own fault if you get oscillation ;-) Attila Kinali -- The trouble with you, Shev, is you don't say anything until you've saved up a whole truckload of damned heavy brick arguments and then you dump them all out and never look at the bleeding body mangled beneath the heap -- Tirin, The Dispossessed, U. Le Guin ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Low noise power supplies - dont' use Electrolytics
On Mon, 28 Nov 2011 16:16:58 -0500 (EST) saidj...@aol.com wrote: Use foil caps to avoid vibration-microphonics. Very expensive, but hey you get what you pay for. Use Tantalum caps if bulk bypassing is needed, using multiple 100uF units if necessary. The design is not right if you need more than say 470uF anyways unless you are switching tens of amps as in an Audio power amp.. I can agree on that, though i also had a design where i used 5*100uF and it was barely enough (a system that usually used just a couple of mA, but occasionaly could draw up to 2A for half a second. Of course, the power supply could only deliver about 500mA) Use ceramic caps where vibration is not an issue. Use high frequency (2MHz) switchers wherever efficiency is required, otherwise use linear regulators. Not really. If you want to have good efficiency, then you want to stay below 1MHz, otherwise switching loses get too high. But the disadvantage is that you have big and bulky capacitors and inductors. Staying somewhere between 1MHz and 1.5 is usually a good compromise if you can tolerate PFM (aka pulse skip) for low load conditions. Going up to 2MHz (and beyond) is only recomended if you are severly space limited. Attila Kinali -- Why does it take years to find the answers to the questions one should have asked long ago? ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Low noise power supplies - dont' use Electrolytics
Hi Attila, I like 2MHz switchers because they use small components (inductors and capacitors) and are easier to filter out at our usual frequencies of interest. The LT3502A for example works at 2.2MHz, which gives harmonics at 8.8MHz and 11MHz, far enough away from 10.0MHz to avoid beating and causing a spur issue. The 1.1MHz part uses a 15uH inductor, the 2.2MHz part only a 4.7uH inductor for the same 1.8V, 500mA application example, a huge difference in size and cost. The capacitor is also 22uF vs. 47uF, again a large size and cost savings for the 2.2MHz part. Not much of an efficiency difference between the 1MHz and 2MHz parts anymore, they are usually around 80% to 85% at 2.2MHz and one or two percent better at 1.1MHz. With proper layout these parts are extremely well behaved and don't have any noticeable ringing etc on the switch as older units did, and they don't create a lot of noise when using shielded inductors. bye, Said In a message dated 11/28/2011 14:22:58 Pacific Standard Time, att...@kinali.ch writes: Use ceramic caps where vibration is not an issue. Use high frequency (2MHz) switchers wherever efficiency is required, otherwise use linear regulators. Not really. If you want to have good efficiency, then you want to stay below 1MHz, otherwise switching loses get too high. But the disadvantage is that you have big and bulky capacitors and inductors. Staying somewhere between 1MHz and 1.5 is usually a good compromise if you can tolerate PFM (aka pulse skip) for low load conditions. Going up to 2MHz (and beyond) is only recomended if you are severly space limited. Attila Kinali ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Low noise power supplies - dont' use Electrolytics
A switcher at 2.2MHz does not have single frequency spikes in its power spectrum, but a rather wideband distribution. It is not a fixed frequency, fixed duty cycle oscillator, but a load-dependent feedback loop that will change duty cycle or frequency (depending on device) to maintain a target output. Check for yourself. Try to get 90% efficiency for instance, from 24V down to 3.5V 5A. Unlikely you can work at 2MHz. -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of saidj...@aol.com Sent: Monday, November 28, 2011 3:06 PM To: time-nuts@febo.com Subject: Re: [time-nuts] Low noise power supplies - dont' use Electrolytics Hi Attila, I like 2MHz switchers because they use small components (inductors and capacitors) and are easier to filter out at our usual frequencies of interest. The LT3502A for example works at 2.2MHz, which gives harmonics at 8.8MHz and 11MHz, far enough away from 10.0MHz to avoid beating and causing a spur issue. The 1.1MHz part uses a 15uH inductor, the 2.2MHz part only a 4.7uH inductor for the same 1.8V, 500mA application example, a huge difference in size and cost. The capacitor is also 22uF vs. 47uF, again a large size and cost savings for the 2.2MHz part. Not much of an efficiency difference between the 1MHz and 2MHz parts anymore, they are usually around 80% to 85% at 2.2MHz and one or two percent better at 1.1MHz. With proper layout these parts are extremely well behaved and don't have any noticeable ringing etc on the switch as older units did, and they don't create a lot of noise when using shielded inductors. bye, Said In a message dated 11/28/2011 14:22:58 Pacific Standard Time, att...@kinali.ch writes: Use ceramic caps where vibration is not an issue. Use high frequency (2MHz) switchers wherever efficiency is required, otherwise use linear regulators. Not really. If you want to have good efficiency, then you want to stay below 1MHz, otherwise switching loses get too high. But the disadvantage is that you have big and bulky capacitors and inductors. Staying somewhere between 1MHz and 1.5 is usually a good compromise if you can tolerate PFM (aka pulse skip) for low load conditions. Going up to 2MHz (and beyond) is only recomended if you are severly space limited. Attila Kinali ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Low noise power supplies - dont' use Electrolytics
Were getting of off the original thread about Electrolytics versus other caps a bit.. A switcher at 2.2MHz does not have single frequency spikes in its power spectrum, but a rather wideband distribution. Yes, that's Fourier 101 basics. But what matters to Time nuts is if the switcher is running close to 1.0MHz or 2.0MHz, as the 10th or 5th harmonics of these would fall right into the phase noise spectrum of the 10.0MHz output and may show up on the usual phase noise plots. It is also easier to filter out a ~2MHz carrier than a ~1MHz carrier from AM-modulating our 10MHz oscillator through the power supply lines. Most of the noise will likely be on the input of the buck switcher, not the output. With a 1MHz switcher, you could have a nasty spur at 10.01MHz right in the spectrum of interest. Running at 2.2MHz moves that spur 1MHz away from the 10MHz carrier, and the possibility of the switcher injection locking with the 10MHz oscillator is reduced. This is easier to accomplish with a 2.2MHz switcher than a 1MHz switcher. but a load-dependent feedback loop that will change duty cycle or frequency (depending on device) to maintain a target output. Check for yourself. The part I listed as an example is a fixed frequency device. Stay away from variable frequency devices for anything Time Nuts related - that is my opinion. Try to get 90% efficiency for instance, from 24V down to 3.5V 5A. Unlikely you can work at 2MHz. A) why would you need 3.5V at 5A for anything time-nuts related? B) you could parallel two or three 2MHz devices to get 5A output power, and synchronize them to each other C) If you are consuming 17.5 Watts at 3.5V in the first place, then why would you care about 90% efficiency versus 85% efficiency in time-nuts related projects? The difference is less than one Watt, and getting 85% from 24V should be possible with the switchers that are out there. We now have commercial Cesium Vapor atomic clocks running at 0.12W and less, so it should be possible to get power consumption down way below 17.5W for most time nuts related equipment I would think... bye, Said In a message dated 11/28/2011 16:43:03 Pacific Standard Time, camar...@quantacorp.com writes: A switcher at 2.2MHz does not have single frequency spikes in its power spectrum, but a rather wideband distribution. It is not a fixed frequency, fixed duty cycle oscillator, but a load-dependent feedback loop that will change duty cycle or frequency (depending on device) to maintain a target output. Check for yourself. Try to get 90% efficiency for instance, from 24V down to 3.5V 5A. Unlikely you can work at 2MHz. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Low noise power supplies - dont' use Electrolytics
I molt them in a high-power charge-pump. The same with WIMA MKS. At normal usage they will last forever and work even at low temperature whereas normal Al caps won't. - Henry gary schrieb: At sane temperatures, OSCONs are very good. Who runs their gear hot enough to boil water? http://edc.sanyo.com/pdf/e_oscon.pdf -- ehydra.dyndns.info ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Low noise power supplies - dont' use Electrolytics
On Fri, 25 Nov 2011 22:25:37 -0800 Chris Albertson albertson.ch...@gmail.com wrote: One question: How does one avoid using electrolytic caps if you need (say) 1,000uF or even 100uF. Those would be some mighty big film caps. I think, aluminium electrolytics are meant, as these have a lot of wear and can die. Hence, you can use tantal or niob electrolytics, which have a dry eletrolyt. Or you can use ceramics which are already available at 100uF. Attila Kinali -- Why does it take years to find the answers to the questions one should have asked long ago? ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Low noise power supplies - dont' use Electrolytics
In message cabbxvhvnsaxbx5uorjtqesttd50yedyavkgxh52bpspuayt...@mail.gmail.com , Chris Albertson writes: One question: How does one avoid using electrolytic caps if you need (say) 1,000uF or even 100uF. Those would be some mighty big film caps. One detail, often overlooked, is that electrolytics seldom are dimensioned very precisely, mostly because they do come with such big capacity but also because them have very big tolerances, +/- 50% is not uncommon. Another effect that causes overdimensioning is that they are not very good capacitors, in particular at higher frequency. I have in a couple of instances replaced electrolytics with film-caps and gotten away with less than 1% of the original capacitance by doing a bit of calculations and measurements on the actual circuit. In one case, an audio circuit had 1000uF for a handful of opamps, using 4.7uF of good film capacitors instead reduced THD by 80%. -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 p...@freebsd.org | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Low noise power supplies - dont' use Electrolytics
On Sat, Nov 26, 2011 at 2:13 AM, gary li...@lazygranch.com wrote: At sane temperatures, OSCONs are very good. Who runs their gear hot enough to boil water? National Fire Protection Agency (NFPA) 2007 edition of their design regulations state the electronics worn by Fire Fighters must work at 500'F for five minutes. In the Paper Pusher's mind the Kevlar clothing can withstand those temperatures, therefor anything else in the Universe can too. Never under estimate the bureaucratic mind... ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Low noise power supplies - dont' use Electrolytics
On Fri, Nov 25, 2011 at 10:36 PM, Raj vu2...@gmail.com wrote: How about this way: Amplifying capacitance.. (Base/Ground cap * Beta) http://sound.westhost.com/project15.htm The above actually uses several quite large electrolytic. It is a good example of why you NEED to use them. Maybe someone can post a schematic of a simple 5V 5A power supply that does NOT use any electro caps. Chris Albertson Redondo Beach, California ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Low noise power supplies - dont' use Electrolytics
On 11/26/11 11:13 AM, Chris Albertson wrote: On Fri, Nov 25, 2011 at 10:36 PM, Rajvu2...@gmail.com wrote: How about this way: Amplifying capacitance.. (Base/Ground cap * Beta) http://sound.westhost.com/project15.htm The above actually uses several quite large electrolytic. It is a good example of why you NEED to use them. Maybe someone can post a schematic of a simple 5V 5A power supply that does NOT use any electro caps. WHat ripple/regulation? 3 phase power and no filter gives you 8% ripple. Chris Albertson Redondo Beach, California ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Low noise power supplies - dont' use Electrolytics
Electrolytic caps have an extremely poor lifetime (MTBF). Sanyo on their website state 50K Hrs at 50C. This means only 6250 MTBF hours at 80C for one single cap. MTBF gets worse the more caps are being used of course. I have seen some Panasonic electrolytics state only 2000 hours MTBF at temperature in their datasheets. That's not even one year before a mean failure occurs making these useless in high-reliability applications. Note also that caps in high AC current situations (Buck DC-DC switcher input cap for example) will self heat due to internal resistance, making things even worse. This is probably one of the main failure reasons for PC motherboards. And that's with name brand parts, it's even worse if one ends up buying counter-fit or non-name-brand Electrolytics. Some of our competitors use Electrolytics all over the place (we don't use any electrolytics) - that's been good for our business. bye, Said In a message dated 11/24/2011 17:08:42 Pacific Standard Time, li...@lazygranch.com writes: I'm not familiar with rubycon caps. The low ESR large value caps are organic semiconductor. OSCON is a common brand from Sanyo. Finding the ultimate cap is nearly as much fun as finding the ultimate LDO. Check out Nichicon. Or you can stick with the Rubycon. Glancing at their website, they seem to copy the Nichicon product line. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Low noise power supplies - dont' use Electrolytics
Many of us have seen electronic equipment last longer then one year. Some of use even have still working antiques with old eletro caps. Those short lifetimes assume a worse case, usually with a very high ripple current. IOf you can reduce the ripple the MTBF goes up. One question: How does one avoid using electrolytic caps if you need (say) 1,000uF or even 100uF. Those would be some mighty big film caps. On Fri, Nov 25, 2011 at 10:06 PM, saidj...@aol.com wrote: Electrolytic caps have an extremely poor lifetime (MTBF). Sanyo on their website state 50K Hrs at 50C. This means only 6250 MTBF hours at 80C for one single cap. MTBF gets worse the more caps are being used of course. I have seen some Panasonic electrolytics state only 2000 hours MTBF at temperature in their datasheets. That's not even one year before a mean failure occurs making these useless in high-reliability applications. Note also that caps in high AC current situations (Buck DC-DC switcher input cap for example) will self heat due to internal resistance, making things even worse. This is probably one of the main failure reasons for PC motherboards. And that's with name brand parts, it's even worse if one ends up buying counter-fit or non-name-brand Electrolytics. Some of our competitors use Electrolytics all over the place (we don't use any electrolytics) - that's been good for our business. bye, Said In a message dated 11/24/2011 17:08:42 Pacific Standard Time, li...@lazygranch.com writes: I'm not familiar with rubycon caps. The low ESR large value caps are organic semiconductor. OSCON is a common brand from Sanyo. Finding the ultimate cap is nearly as much fun as finding the ultimate LDO. Check out Nichicon. Or you can stick with the Rubycon. Glancing at their website, they seem to copy the Nichicon product line. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. -- Chris Albertson Redondo Beach, California ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Low noise power supplies - dont' use Electrolytics
How about this way: Amplifying capacitance.. (Base/Ground cap * Beta) http://sound.westhost.com/project15.htm One question: How does one avoid using electrolytic caps if you need (say) 1,000uF or even 100uF. Those would be some mighty big film caps. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Low noise power supplies - dont' use Electrolytics
To second the older electronics: I maintain nearly 100 analytical instruments. The old designs(1970-late 80's) are almost all electrolytic caps and none of the caps have ever failed. When I do find a bad cap it's always in a modern design. A high frequency switcher with under rated caps. When i say under rated i mean take the peak figure and multiple it by two, that's the real part value. My opinion, bad designs. Steve On Sat, Nov 26, 2011 at 1:25 AM, Chris Albertson albertson.ch...@gmail.comwrote: Many of us have seen electronic equipment last longer then one year. Some of use even have still working antiques with old eletro caps. Those short lifetimes assume a worse case, usually with a very high ripple current. IOf you can reduce the ripple the MTBF goes up. One question: How does one avoid using electrolytic caps if you need (say) 1,000uF or even 100uF. Those would be some mighty big film caps. On Fri, Nov 25, 2011 at 10:06 PM, saidj...@aol.com wrote: Electrolytic caps have an extremely poor lifetime (MTBF). Sanyo on their website state 50K Hrs at 50C. This means only 6250 MTBF hours at 80C for one single cap. MTBF gets worse the more caps are being used of course. I have seen some Panasonic electrolytics state only 2000 hours MTBF at temperature in their datasheets. That's not even one year before a mean failure occurs making these useless in high-reliability applications. Note also that caps in high AC current situations (Buck DC-DC switcher input cap for example) will self heat due to internal resistance, making things even worse. This is probably one of the main failure reasons for PC motherboards. And that's with name brand parts, it's even worse if one ends up buying counter-fit or non-name-brand Electrolytics. Some of our competitors use Electrolytics all over the place (we don't use any electrolytics) - that's been good for our business. bye, Said In a message dated 11/24/2011 17:08:42 Pacific Standard Time, li...@lazygranch.com writes: I'm not familiar with rubycon caps. The low ESR large value caps are organic semiconductor. OSCON is a common brand from Sanyo. Finding the ultimate cap is nearly as much fun as finding the ultimate LDO. Check out Nichicon. Or you can stick with the Rubycon. Glancing at their website, they seem to copy the Nichicon product line. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. -- Chris Albertson Redondo Beach, California ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Low noise power supplies - dont' use Electrolytics
At sane temperatures, OSCONs are very good. Who runs their gear hot enough to boil water? http://edc.sanyo.com/pdf/e_oscon.pdf ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Low noise power supplies for time nuts circuitry
On Wed, 23 Nov 2011 04:50:49 -0800 Chuck Forsberg WA7KGX N2469R c...@omen.com wrote: How well would a pair of cascaded 3 terminal regulators do - say a 7815 feeding a 7812. 78xx Regulators are quite noisy. You can use them to filter the noise of a cheap DC/DC converter, but i wouldnt use them feed high precision electronics. There are a lot better designs these days. Attila Kinali -- The trouble with you, Shev, is you don't say anything until you've saved up a whole truckload of damned heavy brick arguments and then you dump them all out and never look at the bleeding body mangled beneath the heap -- Tirin, The Dispossessed, U. Le Guin ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Low noise power supplies for time nuts circuitry
From a noise and long term stability standpoint, it would not be better than the last device in the chain, and the 78xx series is not great. But you would gain additional ripple and line variation rejection, so if that's what you need to do, it may help. Didier KO4BB Sent from my BlackBerry Wireless thingy while I do other things... -Original Message- From: Chuck Forsberg WA7KGX N2469R c...@omen.com Sender: time-nuts-boun...@febo.com Date: Wed, 23 Nov 2011 04:50:49 To: Discussion of precise time and frequency measurementtime-nuts@febo.com Reply-To: Discussion of precise time and frequency measurement time-nuts@febo.com Subject: Re: [time-nuts] Low noise power supplies for time nuts circuitry How well would a pair of cascaded 3 terminal regulators do - say a 7815 feeding a 7812. How sensitive are each of a Thunderbolt's 3 supplies to noise? On 11/23/2011 04:13 AM, Attila Kinali wrote: On Tue, 22 Nov 2011 12:38:43 -0500 Bob Campli...@rtty.us wrote: There are a couple of circuits (low noise op-amp based) that can generate lower noise than what he's shown. What circuits would that be? Attila Kinali -- Chuck Forsberg WA7KGX N2469R c...@omen.com www.omen.com Developer of Industrial ZMODEM(Tm) for Embedded Applications Omen Technology Inc The High Reliability Software 10255 NW Old Cornelius Pass Portland OR 97231 503-614-0430 ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Low noise power supplies for time nuts circuitry
At 2:28 PM + 11/24/11, time-nuts-requ...@febo.com wrote: Message: 3 Date: Thu, 24 Nov 2011 13:22:38 +0100 From: Attila Kinali att...@kinali.ch To: Discussion of precise time and frequency measurement time-nuts@febo.com Subject: Re: [time-nuts] Low noise power supplies for time nuts circuitry Message-ID: 2024132238.0c810b78.att...@kinali.ch Content-Type: text/plain; charset=US-ASCII On Wed, 23 Nov 2011 04:50:49 -0800 Chuck Forsberg WA7KGX N2469R c...@omen.com wrote: How well would a pair of cascaded 3 terminal regulators do - say a 7815 feeding a 7812. 78xx Regulators are quite noisy. You can use them to filter the noise of a cheap DC/DC converter, but i wouldnt use them feed high precision electronics. There are a lot better designs these days. What I see done in low-noise circuits is a low-noise opamp used as a linear voltage regulator to clean up the output of a 78xx or the like regulator. Joe Gwinn ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Low noise power supplies for time nuts circuitry
78xx Regulators are quite noisy. You can use them to filter the noise of a cheap DC/DC converter, but i wouldnt use them feed high precision electronics. There are a lot better designs these days. Hi Attila, Would you mind recommending some low-noise regulators? Perhaps for both low and high current applications? I'm looking for 12V to power some OXCOs to be used a reference oscillator for a phase noise tester. On the higher current side, maybe to power a rubidium (or at least filter the switcher). Thanks very much, Kevin ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Low noise power supplies for time nuts circuitry
On Nov 23, 2011, at 5:50 AM, Chuck Forsberg WA7KGX N2469R wrote: How sensitive are each of a Thunderbolt's 3 supplies to noise? This doesn't break down the sensitivities to noise, but Tom shows a range of TBolt output noise for different 3 voltage power supplies: http://www.leapsecond.com/pages/tbolt/noise.htm My suspicion is the -12V is the least sensitive as I heard that it is only used for the RS-232 port. I think either the the +5V which controls the electronics (including things like comparators) and the +12V (which controls the heater to the OXCO) are both noise sensitive. I think the +5V will be the most sensitive. For the PRS10 Rb, two 24V inputs are provided. A higher current for the heater and a lower current for the electronics. To my mind, that makes it likely the electronics (+5V on the TBolt) are the most sensitive. Maybe someone will actually have data to show. Kevin ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Low noise power supplies for time nuts circuitry
When you design a regulator, lots of gain is not a criteria in the error amp. (Who needs microvolt accuracy?) High gain generally means two gain stages, which in turn makes it difficult to compensate when driving reactive loads. Thus most op amps are generally a bad idea for an error amp in a regulator. Noise needs to be defined. Generally it means broadband noise. But if your regulator is on the verge of oscillation when the load current or line voltage changes, who cares if the broadband noise is low? This thread is starting to baffle me. Simply dig up a low noise regulator chip. LTC comes to mind. Or troll the net for audiophile shunt designs if you are going to roll your own. What you see done in design often is dubious. Just because it is built, doesn't mean it is good. (Hey, there are doctors that give bad medical advice.) You need to evaluate existing designs for your application. It pays to read the datasheet religiously. Some of these high accuracy regulators can't handle low ESR caps on the output. -Original Message- From: Joe Gwinn joegw...@comcast.net Sender: time-nuts-boun...@febo.com Date: Thu, 24 Nov 2011 10:14:35 To: time-nuts@febo.com Reply-To: Discussion of precise time and frequency measurement time-nuts@febo.com Subject: Re: [time-nuts] Low noise power supplies for time nuts circuitry At 2:28 PM + 11/24/11, time-nuts-requ...@febo.com wrote: Message: 3 Date: Thu, 24 Nov 2011 13:22:38 +0100 From: Attila Kinali att...@kinali.ch To: Discussion of precise time and frequency measurement time-nuts@febo.com Subject: Re: [time-nuts] Low noise power supplies for time nuts circuitry Message-ID: 2024132238.0c810b78.att...@kinali.ch Content-Type: text/plain; charset=US-ASCII On Wed, 23 Nov 2011 04:50:49 -0800 Chuck Forsberg WA7KGX N2469R c...@omen.com wrote: How well would a pair of cascaded 3 terminal regulators do - say a 7815 feeding a 7812. 78xx Regulators are quite noisy. You can use them to filter the noise of a cheap DC/DC converter, but i wouldnt use them feed high precision electronics. There are a lot better designs these days. What I see done in low-noise circuits is a low-noise opamp used as a linear voltage regulator to clean up the output of a 78xx or the like regulator. Joe Gwinn ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Low noise power supplies for time nuts circuitry
The -12V in the TBolt is not used for the serial port. the HIN232 of the TBolt goes from the +5V only, it generates the + and - by the usual switched capacitor technique common to other RS232 interfaces (ADM232, MAX3221 and so on). The -12V powers the LT1014 quad precision opamp that I presume handles the EFC, so care must be taken about the -12 although the PSRR of the opamp comes to the rescue. On Thu, Nov 24, 2011 at 8:25 PM, li...@lazygranch.com wrote: When you design a regulator, lots of gain is not a criteria in the error amp. (Who needs microvolt accuracy?) High gain generally means two gain stages, which in turn makes it difficult to compensate when driving reactive loads. Thus most op amps are generally a bad idea for an error amp in a regulator. Noise needs to be defined. Generally it means broadband noise. But if your regulator is on the verge of oscillation when the load current or line voltage changes, who cares if the broadband noise is low? This thread is starting to baffle me. Simply dig up a low noise regulator chip. LTC comes to mind. Or troll the net for audiophile shunt designs if you are going to roll your own. What you see done in design often is dubious. Just because it is built, doesn't mean it is good. (Hey, there are doctors that give bad medical advice.) You need to evaluate existing designs for your application. It pays to read the datasheet religiously. Some of these high accuracy regulators can't handle low ESR caps on the output. -Original Message- From: Joe Gwinn joegw...@comcast.net Sender: time-nuts-boun...@febo.com Date: Thu, 24 Nov 2011 10:14:35 To: time-nuts@febo.com Reply-To: Discussion of precise time and frequency measurement time-nuts@febo.com Subject: Re: [time-nuts] Low noise power supplies for time nuts circuitry At 2:28 PM + 11/24/11, time-nuts-requ...@febo.com wrote: Message: 3 Date: Thu, 24 Nov 2011 13:22:38 +0100 From: Attila Kinali att...@kinali.ch To: Discussion of precise time and frequency measurement time-nuts@febo.com Subject: Re: [time-nuts] Low noise power supplies for time nuts circuitry Message-ID: 2024132238.0c810b78.att...@kinali.ch Content-Type: text/plain; charset=US-ASCII On Wed, 23 Nov 2011 04:50:49 -0800 Chuck Forsberg WA7KGX N2469R c...@omen.com wrote: How well would a pair of cascaded 3 terminal regulators do - say a 7815 feeding a 7812. 78xx Regulators are quite noisy. You can use them to filter the noise of a cheap DC/DC converter, but i wouldnt use them feed high precision electronics. There are a lot better designs these days. What I see done in low-noise circuits is a low-noise opamp used as a linear voltage regulator to clean up the output of a 78xx or the like regulator. Joe Gwinn ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Low noise power supplies for time nuts circuitry - 40μV Adjustable Voltage Regulator Board
Hi All , I find it interesting that this subject came up just as I was looking into cleaning up some of my supplies that power my RB's. Anyway I just bought two of these to play with http://cgi.ebay.com.au/ws/eBayISAPI.dll?ViewItemitem=130605436528 and they're based on this device... http://www.linear.com/product/LT1764 regards Tim -- VK2XTT :: QF56if :: BMARC :: WIA :: AMSAT-VK :: AMSAT ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Low noise power supplies for time nuts circuitry
Hi The Linear LT1764 is reasonably quiet / high current / low dropout. Don't count on getting all three at once. Bob On Nov 24, 2011, at 12:45 PM, Kevin Rosenberg ke...@rosenberg.net wrote: 78xx Regulators are quite noisy. You can use them to filter the noise of a cheap DC/DC converter, but i wouldnt use them feed high precision electronics. There are a lot better designs these days. Hi Attila, Would you mind recommending some low-noise regulators? Perhaps for both low and high current applications? I'm looking for 12V to power some OXCOs to be used a reference oscillator for a phase noise tester. On the higher current side, maybe to power a rubidium (or at least filter the switcher). Thanks very much, Kevin ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Low noise power supplies for time nuts circuitry - 40μV Adjustable Voltage Regulator Board
The LTC datasheet crows about low current in dropout. Yeah, it's worth crowing about since not all chip use what is called a sat catcher circuit. High current in dropout with PNP pass devices can be a problem. I've seen Micrel regulators that are horrible in dropout. The sat catcher is yet another feedback loop, so it is best to stay out of low dropout if possible. Generally when I buy a LDO, I use the type with a P-fet rather than PNP. I'm not sure if any of these exist with low noise. [I'm usually more concerned with stability.] TI makes good ones. The P-fet pass device doesn't need a sat catcher, so there is one less loop to worry about. Having designed both types, I find the P-fet pass much easier to stabilize. Bipolar devices don't isolated as well as MOS. I'm not familiar with rubycon caps. The low ESR large value caps are organic semiconductor. OSCON is a common brand from Sanyo. Finding the ultimate cap is nearly as much fun as finding the ultimate LDO. Check out Nichicon. Or you can stick with the Rubycon. Glancing at their website, they seem to copy the Nichicon product line. On 11/24/2011 1:37 PM, Tim wrote: Hi All , I find it interesting that this subject came up just as I was looking into cleaning up some of my supplies that power my RB's. Anyway I just bought two of these to play with http://cgi.ebay.com.au/ws/eBayISAPI.dll?ViewItemitem=130605436528 and they're based on this device... http://www.linear.com/product/LT1764 regards Tim ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Low noise power supplies for time nuts circuitry
On Nov 24, 2011, at 4:46 PM, Bob Camp wrote: The Linear LT1764 is reasonably quiet / high current / low dropout. Don't count on getting all three at once. Thanks, Bob! Kevin ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Low noise power supplies for time nuts circuitry
On Thu, 24 Nov 2011 11:45:05 -0700 Kevin Rosenberg ke...@rosenberg.net wrote: 78xx Regulators are quite noisy. You can use them to filter the noise of a cheap DC/DC converter, but i wouldnt use them feed high precision electronics. There are a lot better designs these days. Would you mind recommending some low-noise regulators? Perhaps for both low and high current applications? I'm looking for 12V to power some OXCOs to be used a reference oscillator for a phase noise tester. On the higher current side, maybe to power a rubidium (or at least filter the switcher). As Bob Camp already said, Linear has some low noise LDO's. Also Ti and Analog are worth a look. All three of them also have a lot of app notes describing how to filter power supply noise for instrumentation and PLL applications. A quick googling revealed the following guides: http://www.ti.com/lit/an/slyt201/slyt201.pdf http://www.designers-guide.org/Design/bypassing.pdf HTH Attila Kinali -- Why does it take years to find the answers to the questions one should have asked long ago? ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Low noise power supplies for time nuts circuitry
On Tue, 22 Nov 2011 12:38:43 -0500 Bob Camp li...@rtty.us wrote: There are a couple of circuits (low noise op-amp based) that can generate lower noise than what he's shown. What circuits would that be? Attila Kinali -- The trouble with you, Shev, is you don't say anything until you've saved up a whole truckload of damned heavy brick arguments and then you dump them all out and never look at the bleeding body mangled beneath the heap -- Tirin, The Dispossessed, U. Le Guin ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Low noise power supplies for time nuts circuitry
How well would a pair of cascaded 3 terminal regulators do - say a 7815 feeding a 7812. How sensitive are each of a Thunderbolt's 3 supplies to noise? On 11/23/2011 04:13 AM, Attila Kinali wrote: On Tue, 22 Nov 2011 12:38:43 -0500 Bob Campli...@rtty.us wrote: There are a couple of circuits (low noise op-amp based) that can generate lower noise than what he's shown. What circuits would that be? Attila Kinali -- Chuck Forsberg WA7KGX N2469R c...@omen.com www.omen.com Developer of Industrial ZMODEM(Tm) for Embedded Applications Omen Technology Inc The High Reliability Software 10255 NW Old Cornelius Pass Portland OR 97231 503-614-0430 ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Low noise power supplies for time nuts circuitry
Hi Interesting site - Thanks! A couple of observations: There are a couple of circuits (low noise op-amp based) that can generate lower noise than what he's shown. You need to be careful looking at his results. A lot of what he shows is the result of changing the model used for the output capacitor…. Still well worth looking at. Bob On Nov 22, 2011, at 7:07 AM, Ulrich Bangert wrote: Gentlemen, i would like to draw your attention to this site: http://pstca.com/spice/ripple/ripple.htm The author of this site thank-worthy not only presents circuits for power supply finesse but also simulates them with SPICE. It seems to turn out as if the well known Wenzel suggestions for voltage regulator finesse were not state of the art and other circuits (although similar in principle) may easily outperform them. Best regards Ulrich Bangert Ortholzer Weg1 27243 Gross Ippener Deutschland Tel +49 (0)4224 95071 Fax +49 (0)4224 95072 Mob +49 (0)172 8006546 www.ulrich-bangert.de ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Low noise power supplies for time nuts circuitry
In imaging systems, where the noise on the pixel supply was critical, I had good luck using a buck switcher followed by an LDO, whose maximum PSRR point determined the operating frequency of the switcher. All normal techniques for removing SMPS noise still apply. I used the ISL9000 http://www.intersil.com/products/deviceinfo.asp?pn=ISL9000 since it had the highest PSRR that I could find. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Low noise power supplies for time nuts circuitry
Hi With modern high frequency switchers, often a LC filter between the switcher and the LDO does the trick. The gotcha is that not all the energy is conducted. Radiated energy quickly becomes the issue…. Depending on what you are timing that may be more or less of an issue. 10 MHz distribution is one thing that really does not like the 1 MHz stuff that the newer switchers put out. Bob On Nov 22, 2011, at 12:44 PM, David VanHorn wrote: In imaging systems, where the noise on the pixel supply was critical, I had good luck using a buck switcher followed by an LDO, whose maximum PSRR point determined the operating frequency of the switcher. All normal techniques for removing SMPS noise still apply. I used the ISL9000 http://www.intersil.com/products/deviceinfo.asp?pn=ISL9000 since it had the highest PSRR that I could find. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Low noise power supplies for time nuts circuitry
Omitting the output bypass cap in the single transistor Wenzel cancellation circuit is somewhat misleading in that it reduces the high frequency attenuation, All his other circuits include such caps. A simple tweak (adjusting a resistor ratio) which makes the shunt transistor collector current approximately PTAT significantly reduces the temperature dependence of the cancellation. Bruce Bob Camp wrote: Hi Interesting site - Thanks! A couple of observations: There are a couple of circuits (low noise op-amp based) that can generate lower noise than what he's shown. You need to be careful looking at his results. A lot of what he shows is the result of changing the model used for the output capacitor…. Still well worth looking at. Bob On Nov 22, 2011, at 7:07 AM, Ulrich Bangert wrote: Gentlemen, i would like to draw your attention to this site: http://pstca.com/spice/ripple/ripple.htm The author of this site thank-worthy not only presents circuits for power supply finesse but also simulates them with SPICE. It seems to turn out as if the well known Wenzel suggestions for voltage regulator finesse were not state of the art and other circuits (although similar in principle) may easily outperform them. Best regards Ulrich Bangert Ortholzer Weg1 27243 Gross Ippener Deutschland Tel +49 (0)4224 95071 Fax +49 (0)4224 95072 Mob +49 (0)172 8006546 www.ulrich-bangert.de ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Low noise power supplies for time nuts circuitry
Another potential problem is that the cascaded emitter follower circuit shown is likely to oscillate in the VHF region. An unbypassed resistor in series with the base of each emitter follower should be used. Bruce Bruce Griffiths wrote: Omitting the output bypass cap in the single transistor Wenzel cancellation circuit is somewhat misleading in that it reduces the high frequency attenuation, All his other circuits include such caps. A simple tweak (adjusting a resistor ratio) which makes the shunt transistor collector current approximately PTAT significantly reduces the temperature dependence of the cancellation. Bruce Bob Camp wrote: Hi Interesting site - Thanks! A couple of observations: There are a couple of circuits (low noise op-amp based) that can generate lower noise than what he's shown. You need to be careful looking at his results. A lot of what he shows is the result of changing the model used for the output capacitor…. Still well worth looking at. Bob On Nov 22, 2011, at 7:07 AM, Ulrich Bangert wrote: Gentlemen, i would like to draw your attention to this site: http://pstca.com/spice/ripple/ripple.htm The author of this site thank-worthy not only presents circuits for power supply finesse but also simulates them with SPICE. It seems to turn out as if the well known Wenzel suggestions for voltage regulator finesse were not state of the art and other circuits (although similar in principle) may easily outperform them. Best regards Ulrich Bangert Ortholzer Weg1 27243 Gross Ippener Deutschland Tel +49 (0)4224 95071 Fax +49 (0)4224 95072 Mob +49 (0)172 8006546 www.ulrich-bangert.de ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Low noise power supplies for time nuts circuitry
In message 6f9e458f-b701-49c1-8d83-ebda35784...@ulrich-bangert.de, Ulrich Ban gert writes: It seems to turn out as if the well known Wenzel suggestions for voltage regulator finesse were not state of the art [...] I've played a bit with the Wenzel circuits and they can provide truly outstanding damping, my best was 80dB using a HP VHF transister I can't remember the number of. And yes, they are very sensitive to just about everything, in particular temperature. But getting at good solid 30+dB damping is not _that_ hard, in particular for very low-current constant loads, such as X-tal oscillators. -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 p...@freebsd.org | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Low noise power supplies for time nuts circuitry
As Bob Pease used to say: Spice plots are good for padding bird cages, not much else :) Hittite has a fantastic new ultra low noise LDO for VCO's. Haven't had a chance to check that out, but it looks very promising. Has anyone tried that part here? Also, remember that those caps are microphonic most of the time, and could actually worsen supply noise in the presence of vibration. I get noise floors of below -170dBc with just simple RC or LC filtering on the power supplies, say 10 Ohms into 100uF Tantalum in parallel with some 10nF to 100nF ceramics (or better Polyester caps), all following the typical Linear Technologies low noise LDO's. That will cut off at 160Hz already, and go down at 40dB per decade if two filters are cascaded. Use two 100uF Tantalums or 22Ohms resistors for a 80Hz cut-off. At close-in frequencies, the crystal will likely be the worst noise source and overpower the supply noise by far. It's hard to get better than -108dBc at 1Hz, and -138dBc at 10Hz at 10MHz anyhow. For high frequency switcher noise, use shielded (TDK etc) 33uH inductors in series to a 10 Ohm resistor, into 100uF Tantalums with 10nF and 220pF in paralell. Cuts off 160Hz and has very good isolation at high frequencies without radiating. For the best performance against supply noise, simply use differential techniques. bye, Said In a message dated 11/22/2011 10:52:29 Pacific Standard Time, p...@phk.freebsd.dk writes: In message 6f9e458f-b701-49c1-8d83-ebda35784...@ulrich-bangert.de, Ulrich Ban gert writes: It seems to turn out as if the well known Wenzel suggestions for voltage regulator finesse were not state of the art [...] I've played a bit with the Wenzel circuits and they can provide truly outstanding damping, my best was 80dB using a HP VHF transister I can't remember the number of. And yes, they are very sensitive to just about everything, in particular temperature. But getting at good solid 30+dB damping is not _that_ hard, in particular for very low-current constant loads, such as X-tal oscillators. -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 p...@freebsd.org | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Low noise power supplies for time nuts circuitry
The Hittite parts (there are two versions, one with 1 output and one with 4 outputs, HMC860 and HMC976) unfortunately have a foot note on the data sheet that indicates that the noise numbers are good in the application circuit, which happens to include large capacitors. The capacitors are really doing the work, as indicated by that fact that the noise skyrockets at low frequencies (or else the IC has a servere 1/f noise problem. Therefore, the IC doesn't bring much to the party compared to what you can do yourself with your capacitor and a decent low noise op amp. The Hittite data sheet says that the IC uses a bandgap circuit. A bandgap circuit is inherently noisy because it requires that one of the transistors has to be operated at very low current, and then the output of this transistor is amplified by something like 30 dB and subtracted from the output. Better to have a buried zener/avalanche diode. Rick Karlquist N6RK saidj...@aol.com wrote: Hittite has a fantastic new ultra low noise LDO for VCO's. Haven't had a chance to check that out, but it looks very promising. Has anyone tried that part here? Also, remember that those caps are microphonic most of the time, and could actually worsen supply noise in the presence of vibration. I get noise floors of below -170dBc with just simple RC or LC filtering on the power supplies, say 10 Ohms into 100uF Tantalum in parallel with some 10nF to 100nF ceramics (or better Polyester caps), all following the typical Linear Technologies low noise LDO's. That will cut off at 160Hz already, and go down at 40dB per decade if two filters are cascaded. Use two 100uF Tantalums or 22Ohms resistors for a 80Hz cut-off. At close-in frequencies, the crystal will likely be the worst noise source and overpower the supply noise by far. It's hard to get better than -108dBc at 1Hz, and -138dBc at 10Hz at 10MHz anyhow. For high frequency switcher noise, use shielded (TDK etc) 33uH inductors in series to a 10 Ohm resistor, into 100uF Tantalums with 10nF and 220pF in paralell. Cuts off 160Hz and has very good isolation at high frequencies without radiating. For the best performance against supply noise, simply use differential techniques. bye, Said In a message dated 11/22/2011 10:52:29 Pacific Standard Time, p...@phk.freebsd.dk writes: In message 6f9e458f-b701-49c1-8d83-ebda35784...@ulrich-bangert.de, Ulrich Ban gert writes: It seems to turn out as if the well known Wenzel suggestions for voltage regulator finesse were not state of the art [...] I've played a bit with the Wenzel circuits and they can provide truly outstanding damping, my best was 80dB using a HP VHF transister I can't remember the number of. And yes, they are very sensitive to just about everything, in particular temperature. But getting at good solid 30+dB damping is not _that_ hard, in particular for very low-current constant loads, such as X-tal oscillators. -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 p...@freebsd.org | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Low noise power supplies for time nuts circuitry
If you want low noise voltage regulation, use a shunt regulator. If the load is low current, feed it with a floating current source such as a depletion mode jfet (or several in parallel). These are also sold as current regulating diodes. I've used this scheme in IC designs. You also find it in high end audio design. The shunt design is push pull. If the shunt is designed well, the ultimate high frequency feed through from the power supply, assuming ideal caps, is simply a capacitor divider based on the bypass cap and the capacitance across the current source. The bozos at Broadcom have actually patented using shunt regulation in their chips. Good luck enforcing that patent. -Original Message- From: saidj...@aol.com Sender: time-nuts-boun...@febo.com Date: Tue, 22 Nov 2011 14:18:20 To: time-nuts@febo.com Reply-To: Discussion of precise time and frequency measurement time-nuts@febo.com Subject: Re: [time-nuts] Low noise power supplies for time nuts circuitry As Bob Pease used to say: Spice plots are good for padding bird cages, not much else :) Hittite has a fantastic new ultra low noise LDO for VCO's. Haven't had a chance to check that out, but it looks very promising. Has anyone tried that part here? Also, remember that those caps are microphonic most of the time, and could actually worsen supply noise in the presence of vibration. I get noise floors of below -170dBc with just simple RC or LC filtering on the power supplies, say 10 Ohms into 100uF Tantalum in parallel with some 10nF to 100nF ceramics (or better Polyester caps), all following the typical Linear Technologies low noise LDO's. That will cut off at 160Hz already, and go down at 40dB per decade if two filters are cascaded. Use two 100uF Tantalums or 22Ohms resistors for a 80Hz cut-off. At close-in frequencies, the crystal will likely be the worst noise source and overpower the supply noise by far. It's hard to get better than -108dBc at 1Hz, and -138dBc at 10Hz at 10MHz anyhow. For high frequency switcher noise, use shielded (TDK etc) 33uH inductors in series to a 10 Ohm resistor, into 100uF Tantalums with 10nF and 220pF in paralell. Cuts off 160Hz and has very good isolation at high frequencies without radiating. For the best performance against supply noise, simply use differential techniques. bye, Said In a message dated 11/22/2011 10:52:29 Pacific Standard Time, p...@phk.freebsd.dk writes: In message 6f9e458f-b701-49c1-8d83-ebda35784...@ulrich-bangert.de, Ulrich Ban gert writes: It seems to turn out as if the well known Wenzel suggestions for voltage regulator finesse were not state of the art [...] I've played a bit with the Wenzel circuits and they can provide truly outstanding damping, my best was 80dB using a HP VHF transister I can't remember the number of. And yes, they are very sensitive to just about everything, in particular temperature. But getting at good solid 30+dB damping is not _that_ hard, in particular for very low-current constant loads, such as X-tal oscillators. -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 p...@freebsd.org | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Low noise power supplies for time nuts circuitry
Why is the shunt regulator push-pull? Because of the series regulator first and the shunt regulator then? On Tue, Nov 22, 2011 at 8:59 PM, li...@lazygranch.com wrote: If you want low noise voltage regulation, use a shunt regulator. If the load is low current, feed it with a floating current source such as a depletion mode jfet (or several in parallel). These are also sold as current regulating diodes. I've used this scheme in IC designs. You also find it in high end audio design. The shunt design is push pull. If the shunt is designed well, the ultimate high frequency feed through from the power supply, assuming ideal caps, is simply a capacitor divider based on the bypass cap and the capacitance across the current source. The bozos at Broadcom have actually patented using shunt regulation in their chips. Good luck enforcing that patent. -Original Message- From: saidj...@aol.com Sender: time-nuts-boun...@febo.com Date: Tue, 22 Nov 2011 14:18:20 To: time-nuts@febo.com Reply-To: Discussion of precise time and frequency measurement time-nuts@febo.com Subject: Re: [time-nuts] Low noise power supplies for time nuts circuitry As Bob Pease used to say: Spice plots are good for padding bird cages, not much else :) Hittite has a fantastic new ultra low noise LDO for VCO's. Haven't had a chance to check that out, but it looks very promising. Has anyone tried that part here? Also, remember that those caps are microphonic most of the time, and could actually worsen supply noise in the presence of vibration. I get noise floors of below -170dBc with just simple RC or LC filtering on the power supplies, say 10 Ohms into 100uF Tantalum in parallel with some 10nF to 100nF ceramics (or better Polyester caps), all following the typical Linear Technologies low noise LDO's. That will cut off at 160Hz already, and go down at 40dB per decade if two filters are cascaded. Use two 100uF Tantalums or 22Ohms resistors for a 80Hz cut-off. At close-in frequencies, the crystal will likely be the worst noise source and overpower the supply noise by far. It's hard to get better than -108dBc at 1Hz, and -138dBc at 10Hz at 10MHz anyhow. For high frequency switcher noise, use shielded (TDK etc) 33uH inductors in series to a 10 Ohm resistor, into 100uF Tantalums with 10nF and 220pF in paralell. Cuts off 160Hz and has very good isolation at high frequencies without radiating. For the best performance against supply noise, simply use differential techniques. bye, Said In a message dated 11/22/2011 10:52:29 Pacific Standard Time, p...@phk.freebsd.dk writes: In message 6f9e458f-b701-49c1-8d83-ebda35784...@ulrich-bangert.de, Ulrich Ban gert writes: It seems to turn out as if the well known Wenzel suggestions for voltage regulator finesse were not state of the art [...] I've played a bit with the Wenzel circuits and they can provide truly outstanding damping, my best was 80dB using a HP VHF transister I can't remember the number of. And yes, they are very sensitive to just about everything, in particular temperature. But getting at good solid 30+dB damping is not _that_ hard, in particular for very low-current constant loads, such as X-tal oscillators. -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 p...@freebsd.org | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Low noise power supplies for time nuts circuitry
You are pushing on the load plus shunt with a current source, though traditionally a resistor is used. You are pulling on the source (current source or resistor) with the shunt, which takes any current the load isn't using. The LDO depends on the load to sink current. I have used this scheme where I bootstrap a bandgap by building a shunt regulator around the bandgap, essentially regulating the power supply to the bandgap with the bandgap itself. This is one way to get a high level of PSRR in a chip. The big drawback to a shunt regulator is efficiency. Otherwise, I think they excel in other performance criteria. -Original Message- From: Azelio Boriani azelio.bori...@screen.it Date: Tue, 22 Nov 2011 21:45:47 To: li...@lazygranch.com; Discussion of precise time and frequency measurementtime-nuts@febo.com Subject: Re: [time-nuts] Low noise power supplies for time nuts circuitry Why is the shunt regulator push-pull? Because of the series regulator first and the shunt regulator then? On Tue, Nov 22, 2011 at 8:59 PM, li...@lazygranch.com wrote: If you want low noise voltage regulation, use a shunt regulator. If the load is low current, feed it with a floating current source such as a depletion mode jfet (or several in parallel). These are also sold as current regulating diodes. I've used this scheme in IC designs. You also find it in high end audio design. The shunt design is push pull. If the shunt is designed well, the ultimate high frequency feed through from the power supply, assuming ideal caps, is simply a capacitor divider based on the bypass cap and the capacitance across the current source. The bozos at Broadcom have actually patented using shunt regulation in their chips. Good luck enforcing that patent. -Original Message- From: saidj...@aol.com Sender: time-nuts-boun...@febo.com Date: Tue, 22 Nov 2011 14:18:20 To: time-nuts@febo.com Reply-To: Discussion of precise time and frequency measurement time-nuts@febo.com Subject: Re: [time-nuts] Low noise power supplies for time nuts circuitry As Bob Pease used to say: Spice plots are good for padding bird cages, not much else :) Hittite has a fantastic new ultra low noise LDO for VCO's. Haven't had a chance to check that out, but it looks very promising. Has anyone tried that part here? Also, remember that those caps are microphonic most of the time, and could actually worsen supply noise in the presence of vibration. I get noise floors of below -170dBc with just simple RC or LC filtering on the power supplies, say 10 Ohms into 100uF Tantalum in parallel with some 10nF to 100nF ceramics (or better Polyester caps), all following the typical Linear Technologies low noise LDO's. That will cut off at 160Hz already, and go down at 40dB per decade if two filters are cascaded. Use two 100uF Tantalums or 22Ohms resistors for a 80Hz cut-off. At close-in frequencies, the crystal will likely be the worst noise source and overpower the supply noise by far. It's hard to get better than -108dBc at 1Hz, and -138dBc at 10Hz at 10MHz anyhow. For high frequency switcher noise, use shielded (TDK etc) 33uH inductors in series to a 10 Ohm resistor, into 100uF Tantalums with 10nF and 220pF in paralell. Cuts off 160Hz and has very good isolation at high frequencies without radiating. For the best performance against supply noise, simply use differential techniques. bye, Said In a message dated 11/22/2011 10:52:29 Pacific Standard Time, p...@phk.freebsd.dk writes: In message 6f9e458f-b701-49c1-8d83-ebda35784...@ulrich-bangert.de, Ulrich Ban gert writes: It seems to turn out as if the well known Wenzel suggestions for voltage regulator finesse were not state of the art [...] I've played a bit with the Wenzel circuits and they can provide truly outstanding damping, my best was 80dB using a HP VHF transister I can't remember the number of. And yes, they are very sensitive to just about everything, in particular temperature. But getting at good solid 30+dB damping is not _that_ hard, in particular for very low-current constant loads, such as X-tal oscillators. -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 p...@freebsd.org | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi
Re: [time-nuts] Low noise power supplies for time nuts circuitry
Yes, load isolation is a valuable feature I left out. Perhaps the key feature. The audio designers like it for channel separation. --Original Message-- From: ed breya Sender: time-nuts-boun...@febo.com To: time-nuts@febo.com ReplyTo: Discussion of precise time and frequency measurement Subject: [time-nuts] Low noise power supplies for time nuts circuitry Sent: Nov 22, 2011 2:17 PM The shunt regulator also serves to isolate load current fluctuations from the main supply, since it makes it appear as a constant resistance, current, or power load, depending on the design. This can eliminate cross-talk between various circuitry. For example, I just made one for my new 5065A LED clock design. It makes 4 V for the display, and is able to absorb the nasty 90 mA to 250 mA local range caused by the LED numeric and scan load, but the steps are virtually invisible to the +5 V supply - it looks like about a 4 ohm resistive load into about 4 V source. Ed ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
