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.
[time-nuts] Low noise power supplies for time nuts circuitry
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
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
[time-nuts] Low noise power supplies for time nuts circuitry
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.
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.
Re: [time-nuts] Low noise power supplies for time nuts circuitry
li...@lazygranch.com schrieb: The bozos at Broadcom have actually patented using shunt regulation in their chips. Good luck enforcing that patent. Must be a joke or misunderstanding. Look for example in the datasheet of TCA440. A really old IC. In the internal circuit displayed is a diode shunt regulator serving at the same time as reference divider. - Henry -- 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.
