Re: [time-nuts] Low noise power supply recommendations
Thanks Hal, and Henry, I was wondering about how they acted. I have really nver studied them that much for this type of application. Of course, I have some old moon filters laying around, that are a very low shade, and I could cut up. That could work without having to play with the LED's. Thanks, Will *** REPLY SEPARATOR *** On 6/15/2011 at 8:19 PM ehydra wrote: There get slower with falling current. - Henry -- ehydra.dyndns.info Hal Murray schrieb: I was thinking about trying an orange or yellow LED here, and dimming the LED with the series resistor, trying to make it as dim as the neon bulb, but I don't know if a LED can be dimmed down that low. LEDs work fine at low output levels. At low current, the light output is linear with current. It falls off at high current and/or high temperature. ___ 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. __ Information from ESET Smart Security, version of virus signature database 5851 (20110206) __ The message was checked by ESET Smart Security. http://www.eset.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.
Re: [time-nuts] Low noise power supply recommendations
Will Matney wrote: As far as the power supply is concerned, I think I am going to go with Ni-Cad batteries, and regulate the voltages. I think what they had was nothing more than four step voltages from the battery supply, going from 3, 6 (7), 12, and 24 Vdc, or X2 of the other. From what I saw in the article earlier, an easy zener with emotter follower regulator should do the trick by the comparison with batteries. They used some resistance in series with the zener to reduce noise, but it did decrease the stability somewhat. I have seen this used in some old bias regulation circuits for tubes years ago. A somewhat misguided idea, they really should have used an RC low pass filter between the zener and the output transistor base. The filtering effect is the same but without significantly decreased stability over that of an unfiltered zener.. As far as the noise, I also wondered about this, as ESI used a current limited DC power source to do the same thing, and it was ran off the AC line. Thanks, Will *** REPLY SEPARATOR *** 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 supply recommendations
Bruce, Correct, and by adding the series resistor for higher impedance, the voltage regulation at the zener value is raised from 10 volts to some value higher. I actually remember a variable bias control to a tube using a similar circuit, except the fixed resistor was a pot. He shows using this on a shunt regulator also on the following page. How much unstability this causes at the value given is unknown without actually building the circuit and testing it, but one shouldn't use a series resistor with a zener this way. I remember Rich Measures and myself speaking of this a few years back. One thing that's not mentioned in the article is that certain resistors can cause noise by themselves. Good articles on this are in some power supply and voltage reference App Notes from both Linear Tech., and National. Best, Will *** REPLY SEPARATOR *** On 6/15/2011 at 6:59 PM Bruce Griffiths wrote: Will Matney wrote: As far as the power supply is concerned, I think I am going to go with Ni-Cad batteries, and regulate the voltages. I think what they had was nothing more than four step voltages from the battery supply, going from 3, 6 (7), 12, and 24 Vdc, or X2 of the other. From what I saw in the article earlier, an easy zener with emotter follower regulator should do the trick by the comparison with batteries. They used some resistance in series with the zener to reduce noise, but it did decrease the stability somewhat. I have seen this used in some old bias regulation circuits for tubes years ago. A somewhat misguided idea, they really should have used an RC low pass filter between the zener and the output transistor base. The filtering effect is the same but without significantly decreased stability over that of an unfiltered zener.. As far as the noise, I also wondered about this, as ESI used a current limited DC power source to do the same thing, and it was ran off the AC line. Thanks, Will *** REPLY SEPARATOR *** Bruce __ Information from ESET Smart Security, version of virus signature database 5851 (20110206) __ The message was checked by ESET Smart Security. http://www.eset.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.
Re: [time-nuts] Low noise power supply recommendations
Well a couple of thoughts. As I said modern choppers do work and have big pluses these days. But to the neon bulb. I would use a led thats color more approximates neon. They make them. I rebuilt a HP5360 counter /nixie with modern 7 seg leds that matched the nixie color and it turned out very well. The photo resistors are touchy. The older HP counters actually used neons and photo resistors in the decade counters as the binary to decimal converters. The neon is not standard. Its shorter, typical neons will not fit. My O my has this drifted back to wwvb. Regards Paul On Wed, Jun 15, 2011 at 7:49 AM, Will Matney xfor...@citynet.net wrote: Bruce, Correct, and by adding the series resistor for higher impedance, the voltage regulation at the zener value is raised from 10 volts to some value higher. I actually remember a variable bias control to a tube using a similar circuit, except the fixed resistor was a pot. He shows using this on a shunt regulator also on the following page. How much unstability this causes at the value given is unknown without actually building the circuit and testing it, but one shouldn't use a series resistor with a zener this way. I remember Rich Measures and myself speaking of this a few years back. One thing that's not mentioned in the article is that certain resistors can cause noise by themselves. Good articles on this are in some power supply and voltage reference App Notes from both Linear Tech., and National. Best, Will *** REPLY SEPARATOR *** On 6/15/2011 at 6:59 PM Bruce Griffiths wrote: Will Matney wrote: As far as the power supply is concerned, I think I am going to go with Ni-Cad batteries, and regulate the voltages. I think what they had was nothing more than four step voltages from the battery supply, going from 3, 6 (7), 12, and 24 Vdc, or X2 of the other. From what I saw in the article earlier, an easy zener with emotter follower regulator should do the trick by the comparison with batteries. They used some resistance in series with the zener to reduce noise, but it did decrease the stability somewhat. I have seen this used in some old bias regulation circuits for tubes years ago. A somewhat misguided idea, they really should have used an RC low pass filter between the zener and the output transistor base. The filtering effect is the same but without significantly decreased stability over that of an unfiltered zener.. As far as the noise, I also wondered about this, as ESI used a current limited DC power source to do the same thing, and it was ran off the AC line. Thanks, Will *** REPLY SEPARATOR *** Bruce __ Information from ESET Smart Security, version of virus signature database 5851 (20110206) __ The message was checked by ESET Smart Security. http://www.eset.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 supply recommendations
John, I will check it out, and may do some experiments myself on these. Also, I will take a look at the photo-FET's, as I had forgotten about those. What has me wondering is how neon bulbs act in the circuit, their low brightness, and their drop out times, as I think the on voltage is around 90 volts or so, More like 70. They need a higher voltage to turn on (strike). but the square wave going to them is around 100-115 volts if I recall. I thought about using a simple 10:1 resistive divider, then using a series resistor from that junction going to the LED, the same as for a 10-15 volt supply. Neons run at very low currents. The neon bulbs light goes through two Lucite tubes to the CDS cells, and it couldn't be too bright by the time it reached them. Tubes or rods (as a light guide)? I also thought about using a new form of chopper, as Paul mentions, but making it fit and work could get complicated. ESI quit using the HP 419 in the last models of their 801 DC supply and detector-null meter, and started using a Keithly 155. I either figured it was over this very thing, or HP dropped the 419 from its line. An engineer at Vishay told me that they quit using the Fluke over this neon problem, and went to the Keithly in the last versions of this bridge. OK. I'm going to be using the bridge not only as it was intended, but to do other null measurements, as I added a circuit to use the meter circuit seperatly from the bridge. Thanks, Will Good luck. BTW, the HP thread referred to degradation of the CdS cells. You should read it. It is possible to makle a very high Z chopper with CdS. I'm not so sure about other ways. -John ___ 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 supply recommendations
In message 201106151021530546.2070a...@smtp.citynet.net, Will Matney writes : My guess is that the LED's brightness helped kill the CDS cells. That is not possible by direct effect, light does not hurt CDS cells. It is far more likely that more intense light than designed has decreased the CDS' resistance causing higher current than was good for them. -- 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 supply recommendations
Paul, No, not the direct light emitted from the LED, but the extra current the cell passed was probably over their limit. I thought of placing the LED's vertical to the Lucite rods, instead of horizontal, or head-on, to decrease the intensity. From the side, a LED, it's much dimmer. The NE-3 bulbs are placed this way, but that's about the only way to get the most intensity from them. Another thought would be to place a filter between the LED's and the rods to dim them down. What I was going to do was measure the voltage across the CDS cells, with the neon bulbs running, and try to get a LED to create the same voltage drop, or same amount of current through the cell. Best, Will *** REPLY SEPARATOR *** On 6/15/2011 at 2:25 PM Poul-Henning Kamp wrote: In message 201106151021530546.2070a...@smtp.citynet.net, Will Matney writes : My guess is that the LED's brightness helped kill the CDS cells. That is not possible by direct effect, light does not hurt CDS cells. It is far more likely that more intense light than designed has decreased the CDS' resistance causing higher current than was good for them. -- 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. __ Information from ESET Smart Security, version of virus signature database 5851 (20110206) __ The message was checked by ESET Smart Security. http://www.eset.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.
Re: [time-nuts] Low noise power supply recommendations
John, They used Lucite rods, I shouldn't have said tubes. The neon bulbs are about at the center of the PC board, and the CDS cells are at the edge, so to get the light to them, they used the rods. More than that. They wanted to minimize capacitance coupled between the neons and cells to reducing switching spikes. I think they did the same thing on the 845AB too, but I'm not looking at the manual right now to see for sure, as I'm not sure the 844 and 845 use the same PC board, just the same circuitry. The 844 was sold to other manufacturers, and it came in a plain aluminum box, with the switch shaft sticking out the front. The meter and pots were shipped seperate to be mounted in the customers equipment. HP did the same with the 419, and tacked another letter on the model number, as well as Keithly, which I know uses the same PC board in both versions. Keithly didn't use this type of chopper though (using LED's or lamps). I am going to locate the post on the HP forum and read about it. My guess is that the LED's brightness helped kill the CDS cells. I don't think so. Apparently the CdS cells had aged into uselessness before any LEDS were installed. Read the thread. I was thinking about trying an orange or yellow LED here, and dimming the LED with the series resistor, trying to make it as dim as the neon bulb, but I don't know if a LED can be dimmed down that low. On the old HP 412 VTVM, the incandescent bulbs in it were not very bright, and they were using CDS cells with them. Another instance of this, if I recall, was that Tektronix used a chopper like this in one of their older scope calibrators. Thanks, Will Good luck, -John == ___ 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 supply recommendations
I was thinking about trying an orange or yellow LED here, and dimming the LED with the series resistor, trying to make it as dim as the neon bulb, but I don't know if a LED can be dimmed down that low. LEDs work fine at low output levels. At low current, the light output is linear with current. It falls off at high current and/or high temperature. -- These are my opinions, not necessarily my employer's. I hate spam. ___ 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 supply recommendations
There get slower with falling current. - Henry -- ehydra.dyndns.info Hal Murray schrieb: I was thinking about trying an orange or yellow LED here, and dimming the LED with the series resistor, trying to make it as dim as the neon bulb, but I don't know if a LED can be dimmed down that low. LEDs work fine at low output levels. At low current, the light output is linear with current. It falls off at high current and/or high temperature. ___ 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 supply recommendations
I was just looking at battery noise last week. I assume you need low noise, not good regulation. If so then in practical terms, I think the best thing you could do is get an 8 cell battery holder for AA cells then connect a 220 uF capacitor across it. This is pretty good. has test results for several power supplies http://www.tnt-audio.com/clinica/regulators_noise1_e.html On Tue, Jun 14, 2011 at 4:02 PM, Will Matney xfor...@citynet.net wrote: Hello, I am in need of a very clean 24 Vdc power source, to replace some old mercury cell batteries with. What would a good low noise, clean, power supply be in your recommendations? I thought of using two 12 Vdc lead-acid batteries in series, and making a charging circuit with regulators, but I am hoping to purchase a good used supply off ebay, etc. The old circuit used two 12 Vdc snap terminal mercury batteries in series, for 24 Vdc, along with a 7 Vdc mercury cell, and two plain AA carbon 1.5 Vdc batteries in series for 3 volts. Any help and or ideas would be appreciated. Thanks Will ___ 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 supply recommendations
Hi Ni-cads are a pretty good bet. Bob On Jun 14, 2011, at 7:02 PM, Will Matney xfor...@citynet.net wrote: Hello, I am in need of a very clean 24 Vdc power source, to replace some old mercury cell batteries with. What would a good low noise, clean, power supply be in your recommendations? I thought of using two 12 Vdc lead-acid batteries in series, and making a charging circuit with regulators, but I am hoping to purchase a good used supply off ebay, etc. The old circuit used two 12 Vdc snap terminal mercury batteries in series, for 24 Vdc, along with a 7 Vdc mercury cell, and two plain AA carbon 1.5 Vdc batteries in series for 3 volts. Any help and or ideas would be appreciated. Thanks Will ___ 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 supply recommendations
Chirs, No, actually, I need both. They used the mercury battery over its ability to hold the voltage steady over its charged cycle, which was something they did pretty well. It's a shame they've really not made anything to match them yet, except I've heard of folks using Lithium in their place. I think when they banned mercury cells, it helped with the slow death of Burgess battery, since they produced a good majority of them. The only battery supply that wouldn't have had good regulation, would have been the 3 volt supply using the two AA batteries. The 7 volt, and the 24 volt both used the mercury types. Actually, I think they used 12 and 24 Vdc off the two large mercuries, using the center tap for the 12 volt. This is the supply for a very precise Vishay bridge measuring network. They used a standard line power supply for everything but the supplies feeding the bridge itself. The batteries gave a clean supply voltage, and the mercury type batteries gave the regulation over standard carbon, etc.. I'll take a look at the link on the supplies, and thaks for that. Thanks, Will *** REPLY SEPARATOR *** On 6/14/2011 at 4:46 PM Chris Albertson wrote: I was just looking at battery noise last week. I assume you need low noise, not good regulation. If so then in practical terms, I think the best thing you could do is get an 8 cell battery holder for AA cells then connect a 220 uF capacitor across it. This is pretty good. has test results for several power supplies http://www.tnt-audio.com/clinica/regulators_noise1_e.html On Tue, Jun 14, 2011 at 4:02 PM, Will Matney xfor...@citynet.net wrote: Hello, I am in need of a very clean 24 Vdc power source, to replace some old mercury cell batteries with. What would a good low noise, clean, power supply be in your recommendations? I thought of using two 12 Vdc lead-acid batteries in series, and making a charging circuit with regulators, but I am hoping to purchase a good used supply off ebay, etc. The old circuit used two 12 Vdc snap terminal mercury batteries in series, for 24 Vdc, along with a 7 Vdc mercury cell, and two plain AA carbon 1.5 Vdc batteries in series for 3 volts. Any help and or ideas would be appreciated. Thanks Will ___ 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 __ Information from ESET Smart Security, version of virus signature database 5851 (20110206) __ The message was checked by ESET Smart Security. http://www.eset.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.
Re: [time-nuts] Low noise power supply recommendations
Bob, I've thought about that, and also thought about the 24 volt battery packs used in those Schwinn scooters the kids have. I can buy a 24 volt charger cheap for those, but the batteries run about $60.00 each plus shipping, and they are probably rated at around 4 amp hours, I think. It may be the way I go, since I think they are Ni-Cad instead of lead-acid. The problem is, I wonder what type of noise any voltage regulators will cause in the circuit? Thanks, Will *** REPLY SEPARATOR *** On 6/14/2011 at 8:01 PM Bob Camp wrote: Hi Ni-cads are a pretty good bet. Bob On Jun 14, 2011, at 7:02 PM, Will Matney xfor...@citynet.net wrote: Hello, I am in need of a very clean 24 Vdc power source, to replace some old mercury cell batteries with. What would a good low noise, clean, power supply be in your recommendations? I thought of using two 12 Vdc lead-acid batteries in series, and making a charging circuit with regulators, but I am hoping to purchase a good used supply off ebay, etc. The old circuit used two 12 Vdc snap terminal mercury batteries in series, for 24 Vdc, along with a 7 Vdc mercury cell, and two plain AA carbon 1.5 Vdc batteries in series for 3 volts. Any help and or ideas would be appreciated. Thanks Will ___ 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. __ Information from ESET Smart Security, version of virus signature database 5851 (20110206) __ The message was checked by ESET Smart Security. http://www.eset.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.
Re: [time-nuts] Low noise power supply recommendations
Hi Ni-cads are pretty low noise, reasonably stable, and close to the per cell voltage of the mercury cells. The gotcha is the self discharge rate. If you don't need a floating supply I suspect you can build up a good enough linear regulator to get things working. Bob On Jun 14, 2011, at 8:12 PM, Will Matney xfor...@citynet.net wrote: Bob, I've thought about that, and also thought about the 24 volt battery packs used in those Schwinn scooters the kids have. I can buy a 24 volt charger cheap for those, but the batteries run about $60.00 each plus shipping, and they are probably rated at around 4 amp hours, I think. It may be the way I go, since I think they are Ni-Cad instead of lead-acid. The problem is, I wonder what type of noise any voltage regulators will cause in the circuit? Thanks, Will *** REPLY SEPARATOR *** On 6/14/2011 at 8:01 PM Bob Camp wrote: Hi Ni-cads are a pretty good bet. Bob On Jun 14, 2011, at 7:02 PM, Will Matney xfor...@citynet.net wrote: Hello, I am in need of a very clean 24 Vdc power source, to replace some old mercury cell batteries with. What would a good low noise, clean, power supply be in your recommendations? I thought of using two 12 Vdc lead-acid batteries in series, and making a charging circuit with regulators, but I am hoping to purchase a good used supply off ebay, etc. The old circuit used two 12 Vdc snap terminal mercury batteries in series, for 24 Vdc, along with a 7 Vdc mercury cell, and two plain AA carbon 1.5 Vdc batteries in series for 3 volts. Any help and or ideas would be appreciated. Thanks Will ___ 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. __ Information from ESET Smart Security, version of virus signature database 5851 (20110206) __ The message was checked by ESET Smart Security. http://www.eset.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 supply recommendations
Bob, Yes, and especially after reading the article that Chris posted the link to, I agree. Definately the lead-acid is out, after I saw the noise the battery alone could generate. I always thought they were much cleaner than that, and I wonder what type of havoc that could create on a GPS device in a vehicle? Especially after the IC regulator circuits some use on top of it. Since the ocxo should have a stable and clean rail voltage, after seeing this, it makes one wonder. What was so astounding was that a simple zener controlled series or shunt regulator outpreformed plain battery circuits for noise, and blew away most all IC type regulators. As a matter of fact, I remember these same similar zener circuits used in citizens band base transceivers from my teens, and wonder if they didn't know this then? After all, power source generated noise can play havoc with the audio on any transceiver-receiver system, and in precise measuring circuits too. I think I will most likely use a Ni-Cad battery circuit, then use a version of a zener controlled regulator, that was shown in the article, to obtain all the battery voltages. I might try out a line operated power source feeding it first, but I think the Ni-Cad would be better. Thanks again, Will *** REPLY SEPARATOR *** On 6/14/2011 at 8:24 PM Bob Camp wrote: Hi Ni-cads are pretty low noise, reasonably stable, and close to the per cell voltage of the mercury cells. The gotcha is the self discharge rate. If you don't need a floating supply I suspect you can build up a good enough linear regulator to get things working. Bob On Jun 14, 2011, at 8:12 PM, Will Matney xfor...@citynet.net wrote: Bob, I've thought about that, and also thought about the 24 volt battery packs used in those Schwinn scooters the kids have. I can buy a 24 volt charger cheap for those, but the batteries run about $60.00 each plus shipping, and they are probably rated at around 4 amp hours, I think. It may be the way I go, since I think they are Ni-Cad instead of lead-acid. The problem is, I wonder what type of noise any voltage regulators will cause in the circuit? Thanks, Will *** REPLY SEPARATOR *** On 6/14/2011 at 8:01 PM Bob Camp wrote: Hi Ni-cads are a pretty good bet. Bob On Jun 14, 2011, at 7:02 PM, Will Matney xfor...@citynet.net wrote: Hello, I am in need of a very clean 24 Vdc power source, to replace some old mercury cell batteries with. What would a good low noise, clean, power supply be in your recommendations? I thought of using two 12 Vdc lead-acid batteries in series, and making a charging circuit with regulators, but I am hoping to purchase a good used supply off ebay, etc. The old circuit used two 12 Vdc snap terminal mercury batteries in series, for 24 Vdc, along with a 7 Vdc mercury cell, and two plain AA carbon 1.5 Vdc batteries in series for 3 volts. Any help and or ideas would be appreciated. Thanks Will ___ 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. __ Information from ESET Smart Security, version of virus signature database 5851 (20110206) __ The message was checked by ESET Smart Security. http://www.eset.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. __ Information from ESET Smart Security, version of virus signature database 5851 (20110206) __ The message was checked by ESET Smart Security. http://www.eset.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.
Re: [time-nuts] Low noise power supply recommendations
Hi Will, You could consider building your own power supply system for the replacement of the batteries. Use a separate power transformer which, I suspect, would be small as the current requirements would be low for driving a bridge circuit. The main company to look toward for high quality, low noise regulators is Linear Technology. Here is a candidate part to look at : http://www.linear.com/product/LT3082 This is the lowest noise (33uv/10Hz to 100KHz) low dropout regulator that can handle regulating 24 volts and is adjustable, meaning use can use this part for all three voltages (i.e., three regulators). You will have to decide if it noise specs are suitable for your needs. Keep in mind that battery noise is typically random whereas the noise out of a regulated system tends to be constant. If you really think you need lower noise then you could consider an LT1000 shunt reference. Typically the circuit designs for LT1000 type devices are as references and lack current capability above about 10 milliamps. Adding additional current circuitry would add more noise. See: http://www.linear.com/product/LTZ1000 BillWB6BNQ Will Matney wrote: Hello, I am in need of a very clean 24 Vdc power source, to replace some old mercury cell batteries with. What would a good low noise, clean, power supply be in your recommendations? I thought of using two 12 Vdc lead-acid batteries in series, and making a charging circuit with regulators, but I am hoping to purchase a good used supply off ebay, etc. The old circuit used two 12 Vdc snap terminal mercury batteries in series, for 24 Vdc, along with a 7 Vdc mercury cell, and two plain AA carbon 1.5 Vdc batteries in series for 3 volts. Any help and or ideas would be appreciated. Thanks Will ___ 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 supply recommendations
Bill, I forgot to add, the Vishay bridge uses a Fluke 844 (OEM version of the 845AB) null-microvolt meter to read the bridge circuit. ESI did the same thing, first using a HP 419, and then a Keithly 155 OEM meter assembly, for their bridges. The Fluke has its own supply from the line voltage. The batteries go to the DC current supply for the bridge itself. Thanks, Will *** REPLY SEPARATOR *** On 6/14/2011 at 6:13 PM WB6BNQ wrote: Hi Will, You could consider building your own power supply system for the replacement of the batteries. Use a separate power transformer which, I suspect, would be small as the current requirements would be low for driving a bridge circuit. The main company to look toward for high quality, low noise regulators is Linear Technology. Here is a candidate part to look at : http://www.linear.com/product/LT3082 This is the lowest noise (33uv/10Hz to 100KHz) low dropout regulator that can handle regulating 24 volts and is adjustable, meaning use can use this part for all three voltages (i.e., three regulators). You will have to decide if it noise specs are suitable for your needs. Keep in mind that battery noise is typically random whereas the noise out of a regulated system tends to be constant. If you really think you need lower noise then you could consider an LT1000 shunt reference. Typically the circuit designs for LT1000 type devices are as references and lack current capability above about 10 milliamps. Adding additional current circuitry would add more noise. See: http://www.linear.com/product/LTZ1000 BillWB6BNQ Will Matney wrote: Hello, I am in need of a very clean 24 Vdc power source, to replace some old mercury cell batteries with. What would a good low noise, clean, power supply be in your recommendations? I thought of using two 12 Vdc lead-acid batteries in series, and making a charging circuit with regulators, but I am hoping to purchase a good used supply off ebay, etc. The old circuit used two 12 Vdc snap terminal mercury batteries in series, for 24 Vdc, along with a 7 Vdc mercury cell, and two plain AA carbon 1.5 Vdc batteries in series for 3 volts. Any help and or ideas would be appreciated. Thanks Will ___ 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. __ Information from ESET Smart Security, version of virus signature database 5851 (20110206) __ The message was checked by ESET Smart Security. http://www.eset.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.
Re: [time-nuts] Low noise power supply recommendations
Is the bridge excitation AC or DC. If it's AC, you may not even need low-noise power supplies. -John == Hi Will, You could consider building your own power supply system for the replacement of the batteries. Use a separate power transformer which, I suspect, would be small as the current requirements would be low for driving a bridge circuit. The main company to look toward for high quality, low noise regulators is Linear Technology. Here is a candidate part to look at : http://www.linear.com/product/LT3082 This is the lowest noise (33uv/10Hz to 100KHz) low dropout regulator that can handle regulating 24 volts and is adjustable, meaning use can use this part for all three voltages (i.e., three regulators). You will have to decide if it noise specs are suitable for your needs. Keep in mind that battery noise is typically random whereas the noise out of a regulated system tends to be constant. If you really think you need lower noise then you could consider an LT1000 shunt reference. Typically the circuit designs for LT1000 type devices are as references and lack current capability above about 10 milliamps. Adding additional current circuitry would add more noise. See: http://www.linear.com/product/LTZ1000 BillWB6BNQ Will Matney wrote: Hello, I am in need of a very clean 24 Vdc power source, to replace some old mercury cell batteries with. What would a good low noise, clean, power supply be in your recommendations? I thought of using two 12 Vdc lead-acid batteries in series, and making a charging circuit with regulators, but I am hoping to purchase a good used supply off ebay, etc. The old circuit used two 12 Vdc snap terminal mercury batteries in series, for 24 Vdc, along with a 7 Vdc mercury cell, and two plain AA carbon 1.5 Vdc batteries in series for 3 volts. Any help and or ideas would be appreciated. Thanks Will ___ 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 supply recommendations
John, No, it's DC. I'm trying to meet the original specs of the batteries in not only voltage/current, but cleanliness of the current. Now inside the Fluke 844, it has a chopper, and it uses an AC power supply internally to feed its circuitry. The Vishays bridge uses the batteries voltage, and one small AC power supply to run the digital portion of the bridge for the PPM readout. The bridge itself is half analog and half digital. The analog for the measurement, and the digital for the PPM difference. By the way, has anyone ever converted a neon NE-3 driven chopper to using LED's? The bulbs have a sqaure wave coming into them of around 100-200 Hz if I recall. Thanks, Will *** REPLY SEPARATOR *** On 6/14/2011 at 6:50 PM J. Forster wrote: Is the bridge excitation AC or DC. If it's AC, you may not even need low-noise power supplies. -John == Hi Will, You could consider building your own power supply system for the replacement of the batteries. Use a separate power transformer which, I suspect, would be small as the current requirements would be low for driving a bridge circuit. The main company to look toward for high quality, low noise regulators is Linear Technology. Here is a candidate part to look at : http://www.linear.com/product/LT3082 This is the lowest noise (33uv/10Hz to 100KHz) low dropout regulator that can handle regulating 24 volts and is adjustable, meaning use can use this part for all three voltages (i.e., three regulators). You will have to decide if it noise specs are suitable for your needs. Keep in mind that battery noise is typically random whereas the noise out of a regulated system tends to be constant. If you really think you need lower noise then you could consider an LT1000 shunt reference. Typically the circuit designs for LT1000 type devices are as references and lack current capability above about 10 milliamps. Adding additional current circuitry would add more noise. See: http://www.linear.com/product/LTZ1000 BillWB6BNQ Will Matney wrote: Hello, I am in need of a very clean 24 Vdc power source, to replace some old mercury cell batteries with. What would a good low noise, clean, power supply be in your recommendations? I thought of using two 12 Vdc lead-acid batteries in series, and making a charging circuit with regulators, but I am hoping to purchase a good used supply off ebay, etc. The old circuit used two 12 Vdc snap terminal mercury batteries in series, for 24 Vdc, along with a 7 Vdc mercury cell, and two plain AA carbon 1.5 Vdc batteries in series for 3 volts. Any help and or ideas would be appreciated. Thanks Will ___ 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. __ Information from ESET Smart Security, version of virus signature database 5851 (20110206) __ The message was checked by ESET Smart Security. http://www.eset.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.
Re: [time-nuts] Low noise power supply recommendations
The reason I asked is that most microvolt bridges use choppers and have BP filters at the chopper frequency, so noise is largely uncorrelated. On the neon photochoppers, it has been discussed at length several times on the HP-Agilent Yahyoo Group. A similar thing is used in the 410C. There are apparently issues with the CdS cells. Best, -John === John, No, it's DC. I'm trying to meet the original specs of the batteries in not only voltage/current, but cleanliness of the current. Now inside the Fluke 844, it has a chopper, and it uses an AC power supply internally to feed its circuitry. The Vishays bridge uses the batteries voltage, and one small AC power supply to run the digital portion of the bridge for the PPM readout. The bridge itself is half analog and half digital. The analog for the measurement, and the digital for the PPM difference. By the way, has anyone ever converted a neon NE-3 driven chopper to using LED's? The bulbs have a sqaure wave coming into them of around 100-200 Hz if I recall. Thanks, Will *** REPLY SEPARATOR *** On 6/14/2011 at 6:50 PM J. Forster wrote: Is the bridge excitation AC or DC. If it's AC, you may not even need low-noise power supplies. -John == Hi Will, You could consider building your own power supply system for the replacement of the batteries. Use a separate power transformer which, I suspect, would be small as the current requirements would be low for driving a bridge circuit. The main company to look toward for high quality, low noise regulators is Linear Technology. Here is a candidate part to look at : http://www.linear.com/product/LT3082 This is the lowest noise (33uv/10Hz to 100KHz) low dropout regulator that can handle regulating 24 volts and is adjustable, meaning use can use this part for all three voltages (i.e., three regulators). You will have to decide if it noise specs are suitable for your needs. Keep in mind that battery noise is typically random whereas the noise out of a regulated system tends to be constant. If you really think you need lower noise then you could consider an LT1000 shunt reference. Typically the circuit designs for LT1000 type devices are as references and lack current capability above about 10 milliamps. Adding additional current circuitry would add more noise. See: http://www.linear.com/product/LTZ1000 BillWB6BNQ Will Matney wrote: Hello, I am in need of a very clean 24 Vdc power source, to replace some old mercury cell batteries with. What would a good low noise, clean, power supply be in your recommendations? I thought of using two 12 Vdc lead-acid batteries in series, and making a charging circuit with regulators, but I am hoping to purchase a good used supply off ebay, etc. The old circuit used two 12 Vdc snap terminal mercury batteries in series, for 24 Vdc, along with a 7 Vdc mercury cell, and two plain AA carbon 1.5 Vdc batteries in series for 3 volts. Any help and or ideas would be appreciated. Thanks Will ___ 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. __ Information from ESET Smart Security, version of virus signature database 5851 (20110206) __ The message was checked by ESET Smart Security. http://www.eset.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 supply recommendations
I forgot to add that noise on the bridge excitation should not matter much when the bridge is at null, as the differential mode voltage is zero. -John === John, No, it's DC. I'm trying to meet the original specs of the batteries in not only voltage/current, but cleanliness of the current. Now inside the Fluke 844, it has a chopper, and it uses an AC power supply internally to feed its circuitry. The Vishays bridge uses the batteries voltage, and one small AC power supply to run the digital portion of the bridge for the PPM readout. The bridge itself is half analog and half digital. The analog for the measurement, and the digital for the PPM difference. By the way, has anyone ever converted a neon NE-3 driven chopper to using LED's? The bulbs have a sqaure wave coming into them of around 100-200 Hz if I recall. Thanks, Will *** REPLY SEPARATOR *** On 6/14/2011 at 6:50 PM J. Forster wrote: Is the bridge excitation AC or DC. If it's AC, you may not even need low-noise power supplies. -John == Hi Will, You could consider building your own power supply system for the replacement of the batteries. Use a separate power transformer which, I suspect, would be small as the current requirements would be low for driving a bridge circuit. The main company to look toward for high quality, low noise regulators is Linear Technology. Here is a candidate part to look at : http://www.linear.com/product/LT3082 This is the lowest noise (33uv/10Hz to 100KHz) low dropout regulator that can handle regulating 24 volts and is adjustable, meaning use can use this part for all three voltages (i.e., three regulators). You will have to decide if it noise specs are suitable for your needs. Keep in mind that battery noise is typically random whereas the noise out of a regulated system tends to be constant. If you really think you need lower noise then you could consider an LT1000 shunt reference. Typically the circuit designs for LT1000 type devices are as references and lack current capability above about 10 milliamps. Adding additional current circuitry would add more noise. See: http://www.linear.com/product/LTZ1000 BillWB6BNQ Will Matney wrote: Hello, I am in need of a very clean 24 Vdc power source, to replace some old mercury cell batteries with. What would a good low noise, clean, power supply be in your recommendations? I thought of using two 12 Vdc lead-acid batteries in series, and making a charging circuit with regulators, but I am hoping to purchase a good used supply off ebay, etc. The old circuit used two 12 Vdc snap terminal mercury batteries in series, for 24 Vdc, along with a 7 Vdc mercury cell, and two plain AA carbon 1.5 Vdc batteries in series for 3 volts. Any help and or ideas would be appreciated. Thanks Will ___ 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. __ Information from ESET Smart Security, version of virus signature database 5851 (20110206) __ The message was checked by ESET Smart Security. http://www.eset.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 supply recommendations
Though its a bit off topic Ran into this chopper issue also on a HP410. I replaced the thing with a modern chopper amp. I think an LTC. This was quite a few years ago (10 plus easily) and it works very well. Still does actually. It did take a bit of rework to get things back in balance correctly. On Tue, Jun 14, 2011 at 10:14 PM, J. Forster j...@quik.com wrote: The reason I asked is that most microvolt bridges use choppers and have BP filters at the chopper frequency, so noise is largely uncorrelated. On the neon photochoppers, it has been discussed at length several times on the HP-Agilent Yahyoo Group. A similar thing is used in the 410C. There are apparently issues with the CdS cells. Best, -John === John, No, it's DC. I'm trying to meet the original specs of the batteries in not only voltage/current, but cleanliness of the current. Now inside the Fluke 844, it has a chopper, and it uses an AC power supply internally to feed its circuitry. The Vishays bridge uses the batteries voltage, and one small AC power supply to run the digital portion of the bridge for the PPM readout. The bridge itself is half analog and half digital. The analog for the measurement, and the digital for the PPM difference. By the way, has anyone ever converted a neon NE-3 driven chopper to using LED's? The bulbs have a sqaure wave coming into them of around 100-200 Hz if I recall. Thanks, Will *** REPLY SEPARATOR *** On 6/14/2011 at 6:50 PM J. Forster wrote: Is the bridge excitation AC or DC. If it's AC, you may not even need low-noise power supplies. -John == Hi Will, You could consider building your own power supply system for the replacement of the batteries. Use a separate power transformer which, I suspect, would be small as the current requirements would be low for driving a bridge circuit. The main company to look toward for high quality, low noise regulators is Linear Technology. Here is a candidate part to look at : http://www.linear.com/product/LT3082 This is the lowest noise (33uv/10Hz to 100KHz) low dropout regulator that can handle regulating 24 volts and is adjustable, meaning use can use this part for all three voltages (i.e., three regulators). You will have to decide if it noise specs are suitable for your needs. Keep in mind that battery noise is typically random whereas the noise out of a regulated system tends to be constant. If you really think you need lower noise then you could consider an LT1000 shunt reference. Typically the circuit designs for LT1000 type devices are as references and lack current capability above about 10 milliamps. Adding additional current circuitry would add more noise. See: http://www.linear.com/product/LTZ1000 BillWB6BNQ Will Matney wrote: Hello, I am in need of a very clean 24 Vdc power source, to replace some old mercury cell batteries with. What would a good low noise, clean, power supply be in your recommendations? I thought of using two 12 Vdc lead-acid batteries in series, and making a charging circuit with regulators, but I am hoping to purchase a good used supply off ebay, etc. The old circuit used two 12 Vdc snap terminal mercury batteries in series, for 24 Vdc, along with a 7 Vdc mercury cell, and two plain AA carbon 1.5 Vdc batteries in series for 3 volts. Any help and or ideas would be appreciated. Thanks Will ___ 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. __ Information from ESET Smart Security, version of virus signature database 5851 (20110206) __ The message was checked by ESET Smart Security. http://www.eset.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. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to
Re: [time-nuts] Low noise power supply recommendations
John, I wondered about that, as using a LED is generally in conjunction with a photo-transistor, and not a CDS cell. The reason I thought it might work is that a company years back used them together to form a safety light curtain. The Fluke, and the HP, had a bad rep for those neon bulbs going out and having to be replaced. I am going to replace the ones in the 844 before I button it up, but was wondering if something else could be done. I looked up the life cycle for the NE-3 and it's kind of low, especially compared to a LED. I imagine the problem has to do with the brightness of the LED, as compared to a neon bulb, when using a CDS cell. As far as the power supply is concerned, I think I am going to go with Ni-Cad batteries, and regulate the voltages. I think what they had was nothing more than four step voltages from the battery supply, going from 3, 6 (7), 12, and 24 Vdc, or X2 of the other. From what I saw in the article earlier, an easy zener with emotter follower regulator should do the trick by the comparison with batteries. They used some resistance in series with the zener to reduce noise, but it did decrease the stability somewhat. I have seen this used in some old bias regulation circuits for tubes years ago. As far as the noise, I also wondered about this, as ESI used a current limited DC power source to do the same thing, and it was ran off the AC line. Thanks, Will *** REPLY SEPARATOR *** On 6/14/2011 at 7:14 PM J. Forster wrote: The reason I asked is that most microvolt bridges use choppers and have BP filters at the chopper frequency, so noise is largely uncorrelated. On the neon photochoppers, it has been discussed at length several times on the HP-Agilent Yahyoo Group. A similar thing is used in the 410C. There are apparently issues with the CdS cells. Best, -John === John, No, it's DC. I'm trying to meet the original specs of the batteries in not only voltage/current, but cleanliness of the current. Now inside the Fluke 844, it has a chopper, and it uses an AC power supply internally to feed its circuitry. The Vishays bridge uses the batteries voltage, and one small AC power supply to run the digital portion of the bridge for the PPM readout. The bridge itself is half analog and half digital. The analog for the measurement, and the digital for the PPM difference. By the way, has anyone ever converted a neon NE-3 driven chopper to using LED's? The bulbs have a sqaure wave coming into them of around 100-200 Hz if I recall. Thanks, Will *** REPLY SEPARATOR *** On 6/14/2011 at 6:50 PM J. Forster wrote: Is the bridge excitation AC or DC. If it's AC, you may not even need low-noise power supplies. -John == Hi Will, You could consider building your own power supply system for the replacement of the batteries. Use a separate power transformer which, I suspect, would be small as the current requirements would be low for driving a bridge circuit. The main company to look toward for high quality, low noise regulators is Linear Technology. Here is a candidate part to look at : http://www.linear.com/product/LT3082 This is the lowest noise (33uv/10Hz to 100KHz) low dropout regulator that can handle regulating 24 volts and is adjustable, meaning use can use this part for all three voltages (i.e., three regulators). You will have to decide if it noise specs are suitable for your needs. Keep in mind that battery noise is typically random whereas the noise out of a regulated system tends to be constant. If you really think you need lower noise then you could consider an LT1000 shunt reference. Typically the circuit designs for LT1000 type devices are as references and lack current capability above about 10 milliamps. Adding additional current circuitry would add more noise. See: http://www.linear.com/product/LTZ1000 BillWB6BNQ Will Matney wrote: Hello, I am in need of a very clean 24 Vdc power source, to replace some old mercury cell batteries with. What would a good low noise, clean, power supply be in your recommendations? I thought of using two 12 Vdc lead-acid batteries in series, and making a charging circuit with regulators, but I am hoping to purchase a good used supply off ebay, etc. The old circuit used two 12 Vdc snap terminal mercury batteries in series, for 24 Vdc, along with a 7 Vdc mercury cell, and two plain AA carbon 1.5 Vdc batteries in series for 3 volts. Any help and or ideas would be appreciated. Thanks Will ___ 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
Re: [time-nuts] Low noise power supply recommendations
Hi Will, I don't know. Check the HP Group archives. I only vaguely followed the thread. I'm not so sure a phototransistor will work without circuit mods. A photoFET might. Best, -John === John, I wondered about that, as using a LED is generally in conjunction with a photo-transistor, and not a CDS cell. The reason I thought it might work is that a company years back used them together to form a safety light curtain. The Fluke, and the HP, had a bad rep for those neon bulbs going out and having to be replaced. I am going to replace the ones in the 844 before I button it up, but was wondering if something else could be done. I looked up the life cycle for the NE-3 and it's kind of low, especially compared to a LED. I imagine the problem has to do with the brightness of the LED, as compared to a neon bulb, when using a CDS cell. As far as the power supply is concerned, I think I am going to go with Ni-Cad batteries, and regulate the voltages. I think what they had was nothing more than four step voltages from the battery supply, going from 3, 6 (7), 12, and 24 Vdc, or X2 of the other. From what I saw in the article earlier, an easy zener with emotter follower regulator should do the trick by the comparison with batteries. They used some resistance in series with the zener to reduce noise, but it did decrease the stability somewhat. I have seen this used in some old bias regulation circuits for tubes years ago. As far as the noise, I also wondered about this, as ESI used a current limited DC power source to do the same thing, and it was ran off the AC line. Thanks, Will *** REPLY SEPARATOR *** On 6/14/2011 at 7:14 PM J. Forster wrote: The reason I asked is that most microvolt bridges use choppers and have BP filters at the chopper frequency, so noise is largely uncorrelated. On the neon photochoppers, it has been discussed at length several times on the HP-Agilent Yahyoo Group. A similar thing is used in the 410C. There are apparently issues with the CdS cells. Best, -John === John, No, it's DC. I'm trying to meet the original specs of the batteries in not only voltage/current, but cleanliness of the current. Now inside the Fluke 844, it has a chopper, and it uses an AC power supply internally to feed its circuitry. The Vishays bridge uses the batteries voltage, and one small AC power supply to run the digital portion of the bridge for the PPM readout. The bridge itself is half analog and half digital. The analog for the measurement, and the digital for the PPM difference. By the way, has anyone ever converted a neon NE-3 driven chopper to using LED's? The bulbs have a sqaure wave coming into them of around 100-200 Hz if I recall. Thanks, Will *** REPLY SEPARATOR *** On 6/14/2011 at 6:50 PM J. Forster wrote: Is the bridge excitation AC or DC. If it's AC, you may not even need low-noise power supplies. -John == Hi Will, You could consider building your own power supply system for the replacement of the batteries. Use a separate power transformer which, I suspect, would be small as the current requirements would be low for driving a bridge circuit. The main company to look toward for high quality, low noise regulators is Linear Technology. Here is a candidate part to look at : http://www.linear.com/product/LT3082 This is the lowest noise (33uv/10Hz to 100KHz) low dropout regulator that can handle regulating 24 volts and is adjustable, meaning use can use this part for all three voltages (i.e., three regulators). You will have to decide if it noise specs are suitable for your needs. Keep in mind that battery noise is typically random whereas the noise out of a regulated system tends to be constant. If you really think you need lower noise then you could consider an LT1000 shunt reference. Typically the circuit designs for LT1000 type devices are as references and lack current capability above about 10 milliamps. Adding additional current circuitry would add more noise. See: http://www.linear.com/product/LTZ1000 BillWB6BNQ Will Matney wrote: Hello, I am in need of a very clean 24 Vdc power source, to replace some old mercury cell batteries with. What would a good low noise, clean, power supply be in your recommendations? I thought of using two 12 Vdc lead-acid batteries in series, and making a charging circuit with regulators, but I am hoping to purchase a good used supply off ebay, etc. The old circuit used two 12 Vdc snap terminal mercury batteries in series, for 24 Vdc, along with a 7 Vdc mercury cell, and two plain AA carbon 1.5 Vdc batteries in series for 3 volts. Any help and or ideas would be appreciated. Thanks Will ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to
Re: [time-nuts] Low noise power supply recommendations
Paul, Remember the HP 412? It used incandescent bulbs, a spinning disc, and a syncronous motor. I actually still use two of these, and the bulbs are the only fault. Best, Will *** REPLY SEPARATOR *** On 6/14/2011 at 10:21 PM paul swed wrote: Though its a bit off topic Ran into this chopper issue also on a HP410. I replaced the thing with a modern chopper amp. I think an LTC. This was quite a few years ago (10 plus easily) and it works very well. Still does actually. It did take a bit of rework to get things back in balance correctly. On Tue, Jun 14, 2011 at 10:14 PM, J. Forster j...@quik.com wrote: The reason I asked is that most microvolt bridges use choppers and have BP filters at the chopper frequency, so noise is largely uncorrelated. On the neon photochoppers, it has been discussed at length several times on the HP-Agilent Yahyoo Group. A similar thing is used in the 410C. There are apparently issues with the CdS cells. Best, -John === John, No, it's DC. I'm trying to meet the original specs of the batteries in not only voltage/current, but cleanliness of the current. Now inside the Fluke 844, it has a chopper, and it uses an AC power supply internally to feed its circuitry. The Vishays bridge uses the batteries voltage, and one small AC power supply to run the digital portion of the bridge for the PPM readout. The bridge itself is half analog and half digital. The analog for the measurement, and the digital for the PPM difference. By the way, has anyone ever converted a neon NE-3 driven chopper to using LED's? The bulbs have a sqaure wave coming into them of around 100-200 Hz if I recall. Thanks, Will *** REPLY SEPARATOR *** On 6/14/2011 at 6:50 PM J. Forster wrote: Is the bridge excitation AC or DC. If it's AC, you may not even need low-noise power supplies. -John == Hi Will, You could consider building your own power supply system for the replacement of the batteries. Use a separate power transformer which, I suspect, would be small as the current requirements would be low for driving a bridge circuit. The main company to look toward for high quality, low noise regulators is Linear Technology. Here is a candidate part to look at : http://www.linear.com/product/LT3082 This is the lowest noise (33uv/10Hz to 100KHz) low dropout regulator that can handle regulating 24 volts and is adjustable, meaning use can use this part for all three voltages (i.e., three regulators). You will have to decide if it noise specs are suitable for your needs. Keep in mind that battery noise is typically random whereas the noise out of a regulated system tends to be constant. If you really think you need lower noise then you could consider an LT1000 shunt reference. Typically the circuit designs for LT1000 type devices are as references and lack current capability above about 10 milliamps. Adding additional current circuitry would add more noise. See: http://www.linear.com/product/LTZ1000 BillWB6BNQ Will Matney wrote: Hello, I am in need of a very clean 24 Vdc power source, to replace some old mercury cell batteries with. What would a good low noise, clean, power supply be in your recommendations? I thought of using two 12 Vdc lead-acid batteries in series, and making a charging circuit with regulators, but I am hoping to purchase a good used supply off ebay, etc. The old circuit used two 12 Vdc snap terminal mercury batteries in series, for 24 Vdc, along with a 7 Vdc mercury cell, and two plain AA carbon 1.5 Vdc batteries in series for 3 volts. Any help and or ideas would be appreciated. Thanks Will ___ 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. __ Information from ESET Smart Security, version of virus signature database 5851 (20110206) __ The message was checked by ESET Smart Security. http://www.eset.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 --
Re: [time-nuts] Low noise power supply recommendations
Paul, Remember the HP 412? It used incandescent bulbs, a spinning disc, and a syncronous motor. I actually still use two of these, and the bulbs are the only fault. Getting back on topic, somewhat, has anyone ever checked the noise on the rails feeding the OCXO's in this GPS equipment? Especially the ones ruiing off 12 volt car lead-acid batteries? The reason for the question is, I was always taught that batteries were the best souce, when noise or cleaness of supply voltage was needed. It was never stated which battery to use, etc. From the article, it said that alkaline batteries had a cleaner supply than others, but then again, their not rechargable. Does anyone remember anything about the mercury batteries? Best, Will *** REPLY SEPARATOR *** On 6/14/2011 at 10:21 PM paul swed wrote: Though its a bit off topic Ran into this chopper issue also on a HP410. I replaced the thing with a modern chopper amp. I think an LTC. This was quite a few years ago (10 plus easily) and it works very well. Still does actually. It did take a bit of rework to get things back in balance correctly. On Tue, Jun 14, 2011 at 10:14 PM, J. Forster j...@quik.com wrote: The reason I asked is that most microvolt bridges use choppers and have BP filters at the chopper frequency, so noise is largely uncorrelated. On the neon photochoppers, it has been discussed at length several times on the HP-Agilent Yahyoo Group. A similar thing is used in the 410C. There are apparently issues with the CdS cells. Best, -John === John, No, it's DC. I'm trying to meet the original specs of the batteries in not only voltage/current, but cleanliness of the current. Now inside the Fluke 844, it has a chopper, and it uses an AC power supply internally to feed its circuitry. The Vishays bridge uses the batteries voltage, and one small AC power supply to run the digital portion of the bridge for the PPM readout. The bridge itself is half analog and half digital. The analog for the measurement, and the digital for the PPM difference. By the way, has anyone ever converted a neon NE-3 driven chopper to using LED's? The bulbs have a sqaure wave coming into them of around 100-200 Hz if I recall. Thanks, Will *** REPLY SEPARATOR *** On 6/14/2011 at 6:50 PM J. Forster wrote: Is the bridge excitation AC or DC. If it's AC, you may not even need low-noise power supplies. -John == Hi Will, You could consider building your own power supply system for the replacement of the batteries. Use a separate power transformer which, I suspect, would be small as the current requirements would be low for driving a bridge circuit. The main company to look toward for high quality, low noise regulators is Linear Technology. Here is a candidate part to look at : http://www.linear.com/product/LT3082 This is the lowest noise (33uv/10Hz to 100KHz) low dropout regulator that can handle regulating 24 volts and is adjustable, meaning use can use this part for all three voltages (i.e., three regulators). You will have to decide if it noise specs are suitable for your needs. Keep in mind that battery noise is typically random whereas the noise out of a regulated system tends to be constant. If you really think you need lower noise then you could consider an LT1000 shunt reference. Typically the circuit designs for LT1000 type devices are as references and lack current capability above about 10 milliamps. Adding additional current circuitry would add more noise. See: http://www.linear.com/product/LTZ1000 BillWB6BNQ Will Matney wrote: Hello, I am in need of a very clean 24 Vdc power source, to replace some old mercury cell batteries with. What would a good low noise, clean, power supply be in your recommendations? I thought of using two 12 Vdc lead-acid batteries in series, and making a charging circuit with regulators, but I am hoping to purchase a good used supply off ebay, etc. The old circuit used two 12 Vdc snap terminal mercury batteries in series, for 24 Vdc, along with a 7 Vdc mercury cell, and two plain AA carbon 1.5 Vdc batteries in series for 3 volts. Any help and or ideas would be appreciated. Thanks Will ___ 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
Re: [time-nuts] Low noise power supply recommendations
John, I will check it out, and may do some experiments myself on these. Also, I will take a look at the photo-FET's, as I had forgotten about those. What has me wondering is how neon bulbs act in the circuit, their low brightness, and their drop out times, as I think the on voltage is around 90 volts or so, but the square wave going to them is around 100-115 volts if I recall. I thought about using a simple 10:1 resistive divider, then using a series resistor from that junction going to the LED, the same as for a 10-15 volt supply. The neon bulbs light goes through two Lucite tubes to the CDS cells, and it couldn't be too bright by the time it reached them. I also thought about using a new form of chopper, as Paul mentions, but making it fit and work could get complicated. ESI quit using the HP 419 in the last models of their 801 DC supply and detector-null meter, and started using a Keithly 155. I either figured it was over this very thing, or HP dropped the 419 from its line. An engineer at Vishay told me that they quit using the Fluke over this neon problem, and went to the Keithly in the last versions of this bridge. I'm going to be using the bridge not only as it was intended, but to do other null measurements, as I added a circuit to use the meter circuit seperatly from the bridge. Thanks, Will *** REPLY SEPARATOR *** On 6/14/2011 at 8:13 PM J. Forster wrote: Hi Will, I don't know. Check the HP Group archives. I only vaguely followed the thread. I'm not so sure a phototransistor will work without circuit mods. A photoFET might. Best, -John === John, I wondered about that, as using a LED is generally in conjunction with a photo-transistor, and not a CDS cell. The reason I thought it might work is that a company years back used them together to form a safety light curtain. The Fluke, and the HP, had a bad rep for those neon bulbs going out and having to be replaced. I am going to replace the ones in the 844 before I button it up, but was wondering if something else could be done. I looked up the life cycle for the NE-3 and it's kind of low, especially compared to a LED. I imagine the problem has to do with the brightness of the LED, as compared to a neon bulb, when using a CDS cell. As far as the power supply is concerned, I think I am going to go with Ni-Cad batteries, and regulate the voltages. I think what they had was nothing more than four step voltages from the battery supply, going from 3, 6 (7), 12, and 24 Vdc, or X2 of the other. From what I saw in the article earlier, an easy zener with emotter follower regulator should do the trick by the comparison with batteries. They used some resistance in series with the zener to reduce noise, but it did decrease the stability somewhat. I have seen this used in some old bias regulation circuits for tubes years ago. As far as the noise, I also wondered about this, as ESI used a current limited DC power source to do the same thing, and it was ran off the AC line. Thanks, Will *** REPLY SEPARATOR *** On 6/14/2011 at 7:14 PM J. Forster wrote: The reason I asked is that most microvolt bridges use choppers and have BP filters at the chopper frequency, so noise is largely uncorrelated. On the neon photochoppers, it has been discussed at length several times on the HP-Agilent Yahyoo Group. A similar thing is used in the 410C. There are apparently issues with the CdS cells. Best, -John === John, No, it's DC. I'm trying to meet the original specs of the batteries in not only voltage/current, but cleanliness of the current. Now inside the Fluke 844, it has a chopper, and it uses an AC power supply internally to feed its circuitry. The Vishays bridge uses the batteries voltage, and one small AC power supply to run the digital portion of the bridge for the PPM readout. The bridge itself is half analog and half digital. The analog for the measurement, and the digital for the PPM difference. By the way, has anyone ever converted a neon NE-3 driven chopper to using LED's? The bulbs have a sqaure wave coming into them of around 100-200 Hz if I recall. Thanks, Will *** REPLY SEPARATOR *** On 6/14/2011 at 6:50 PM J. Forster wrote: Is the bridge excitation AC or DC. If it's AC, you may not even need low-noise power supplies. -John == Hi Will, You could consider building your own power supply system for the replacement of the batteries. Use a separate power transformer which, I suspect, would be small as the current requirements would be low for driving a bridge circuit. The main company to look toward for high quality, low noise regulators is Linear Technology. Here is a candidate part to look at : http://www.linear.com/product/LT3082 This is the lowest noise (33uv/10Hz to 100KHz) low dropout regulator that can handle regulating 24 volts and is adjustable, meaning use
Re: [time-nuts] Low noise power supply
H I wasn't impressed. The 'scope screen shot of noise levels on the outputs used 20mV/division, and the thickness of the regulated traces told us precisely nothing. Now if the author had measured 20uV noise over a BW of 10Hz to 100kHz (about 63nV/rtHz), or 3uV over the same BW (about 10nV/rtHz), I'd have started to get interested. However as no claims were made, I took the title of Ultra-Low Noise with a large shovel of salt. Regards, David Partridge -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of ewkeh...@aol.com Sent: 08 March 2011 21:41 To: time-nuts@febo.com Subject: [time-nuts] Low noise power supply There is an interesting article in the March 2011 Electronic Products magazine design an ultra low noise supply for analog circuits. It is a combination of switcher and LDO's and written by P Hunter TI so it may also be available on their site. Bert Kehren ___ 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 supply
If one can say that the actual noise-floor signal is approx. white noise than the peak to average is a factor of 6 to 7 on a analog scope. I once read this somewhere and found it not a so bad decision. - Henry -- ehydra.dyndns.info David C. Partridge schrieb: H I wasn't impressed. The 'scope screen shot of noise levels on the outputs used 20mV/division, and the thickness of the regulated traces told us precisely nothing. Now if the author had measured 20uV noise over a BW of 10Hz to 100kHz (about 63nV/rtHz), or 3uV over the same BW (about 10nV/rtHz), I'd have started to get interested. However as no claims were made, I took the title of Ultra-Low Noise with a large shovel of salt. Regards, David Partridge ___ 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 supply
For me, this looks like a advertisement campaign only. Not very sophisticated or ingenious. Read that you don't need LC-filters at the output because of the LDOs. *lol* If the designer ever heard of corner frequency?? And the ISL9000A is the same. - Henry -- ehydra.dyndns.info David C. Partridge schrieb: H I wasn't impressed. The 'scope screen shot of noise levels on the outputs used 20mV/division, and the thickness of the regulated traces told us precisely nothing. Now if the author had measured 20uV noise over a BW of 10Hz to 100kHz (about 63nV/rtHz), or 3uV over the same BW (about 10nV/rtHz), I'd have started to get interested. However as no claims were made, I took the title of Ultra-Low Noise with a large shovel of salt. Regards, David Partridge -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of ewkeh...@aol.com Sent: 08 March 2011 21:41 To: time-nuts@febo.com Subject: [time-nuts] Low noise power supply There is an interesting article in the March 2011 Electronic Products magazine design an ultra low noise supply for analog circuits. It is a combination of switcher and LDO's and written by P Hunter TI so it may also be available on their site. Bert Kehren ___ 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 supply
Electronic Products is not a real engineering publication. It is a forum purely for new product releases. Always has been. Articles there are almost always written by applications engineers for the product being touted. I got it free for decades, and threw the magazine away at once, unread. Why, you ask? Simple, the EEM... Electronic Engineers' Master, the giant, multi-volume industry directory with company names and phone numbers, about the size of a cinder block... came free, with a subscription. Best, -John = For me, this looks like a advertisement campaign only. Not very sophisticated or ingenious. Read that you don't need LC-filters at the output because of the LDOs. *lol* If the designer ever heard of corner frequency?? And the ISL9000A is the same. - Henry -- ehydra.dyndns.info David C. Partridge schrieb: H I wasn't impressed. The 'scope screen shot of noise levels on the outputs used 20mV/division, and the thickness of the regulated traces told us precisely nothing. Now if the author had measured 20uV noise over a BW of 10Hz to 100kHz (about 63nV/rtHz), or 3uV over the same BW (about 10nV/rtHz), I'd have started to get interested. However as no claims were made, I took the title of Ultra-Low Noise with a large shovel of salt. Regards, David Partridge -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of ewkeh...@aol.com Sent: 08 March 2011 21:41 To: time-nuts@febo.com Subject: [time-nuts] Low noise power supply There is an interesting article in the March 2011 Electronic Products magazine design an ultra low noise supply for analog circuits. It is a combination of switcher and LDO's and written by P Hunter TI so it may also be available on their site. Bert Kehren ___ 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 supply
Hi John and group - For us germans, american magazines always look overloaded with advertisments. The marketenders don't like to hear that the generations under 40-50 are mostly advertisment blind just by natural adaption. The times where I read paper electronics are long gone. The Internet completely took over. Sometimes I go for wooden pdfs in the local university library. But back to the interesting subject - that I personally not fully resolved so there is a need of discussion! Here is a first insight: http://waltjung.org/PDFs/Sources_101_P2.pdf In general: LDO is bad. low Iq is bad too. cheers - Henry -- ehydra.dyndns.info J. Forster schrieb: Electronic Products is not a real engineering publication. It is a forum purely for new product releases. Always has been. Articles there are almost always written by applications engineers for the product being touted. I got it free for decades, and threw the magazine away at once, unread. Why, you ask? Simple, the EEM... Electronic Engineers' Master, the giant, multi-volume industry directory with company names and phone numbers, about the size of a cinder block... came free, with a subscription. Best, -John ___ 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 supply
At 16:41 -0500 08-03-2011, ewkeh...@aol.com wrote: There is an interesting article in the March 2011 Electronic Products magazine design an ultra low noise supply for analog circuits. It is a combination of switcher and LDO's and written by P Hunter TI so it may also be available on their site. This one, I presume: http://www2.electronicproducts.com/Designing_an_ultra_low_noise_supply_for_analog_circuits-article-fapo_TI_mar2011-html.aspx ? Bit of a shame to use LDOs and then still drop 50% of the output voltage. Also, Fig 2 is meaningless without a measurement bandwidth spec. There are other ways to get a cleaner bipolar supply from a switcher, several of them simpler than what's shown here. You could take a SEPIC/Cuk hybrid, or pick a switcher that allows you to trade efficiency for switch slew rate like the LT1533. Some useful techniques are documented in http://www.linear.com/docs/4159. JDB. [not affiliated with Linear Tech other than being a satisfied customer] -- Years from now, if you are doing something quick and dirty, you imagine that I am looking over your shoulder and say to yourself, Dijkstra would not like this, well that would be immortality for me. -- Edsger Dijkstra, 1930 - 2002 ___ 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 supply
Here: http://www2.electronicproducts.com/Designing_an_ultra_low_noise_supply_for_analog_circuits-article-fapo_TI_mar2011-html.aspx - Henry -- ehydra.dyndns.info ewkeh...@aol.com schrieb: There is an interesting article in the March 2011 Electronic Products magazine design an ultra low noise supply for analog circuits. It is a combination of switcher and LDO's and written by P Hunter TI so it may also be available on their site. Bert Kehren ___ 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 supply
This is not a low noise PS, IMO. There is far too much ripple on the outputs for that. Furthermore, I'd bet it has real radiated EMI issues. -John = At 16:41 -0500 08-03-2011, ewkeh...@aol.com wrote: There is an interesting article in the March 2011 Electronic Products magazine design an ultra low noise supply for analog circuits. It is a combination of switcher and LDO's and written by P Hunter TI so it may also be available on their site. This one, I presume: http://www2.electronicproducts.com/Designing_an_ultra_low_noise_supply_for_analog_circuits-article-fapo_TI_mar2011-html.aspx ? Bit of a shame to use LDOs and then still drop 50% of the output voltage. Also, Fig 2 is meaningless without a measurement bandwidth spec. There are other ways to get a cleaner bipolar supply from a switcher, several of them simpler than what's shown here. You could take a SEPIC/Cuk hybrid, or pick a switcher that allows you to trade efficiency for switch slew rate like the LT1533. Some useful techniques are documented in http://www.linear.com/docs/4159. JDB. [not affiliated with Linear Tech other than being a satisfied customer] -- Years from now, if you are doing something quick and dirty, you imagine that I am looking over your shoulder and say to yourself, Dijkstra would not like this, well that would be immortality for me. -- Edsger Dijkstra, 1930 - 2002 ___ 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 supply
I had this problem when using some ultra low light imagers. They have NO PSRR, and the integration times were up in the 1-3 second range, so any noise on the pixel supply ended up in the image. I used an ICL-9000 regulator which has ultra high PSRR, and I used a switcher running at a specific rate where the ICL-9000 has maximum PSRR. I also was very concerned with waste power, so the SMPS was set up for the output to be just high enough for the linear to stay in regulation. For this app you'd want a beefier reg, but search for high PSRR at the right current range and work backward from there. Layout is also HUGE in keeping switchers quiet. Most of what I do has switchers in the 1-5W range, and I only use two layer boards, but I get my noise low enough that both the pre-scan with GTEM and OATS site can't see whether I'm on or off. (conducted or radiated thru 15 GHz) -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of ewkeh...@aol.com Sent: Tuesday, March 08, 2011 2:41 PM To: time-nuts@febo.com Subject: [time-nuts] Low noise power supply There is an interesting article in the March 2011 Electronic Products magazine design an ultra low noise supply for analog circuits. It is a combination of switcher and LDO's and written by P Hunter TI so it may also be available on their site. Bert Kehren ___ 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 supply
I used an ICL-9000 regulator ISL-9000. Sorry. http://www.intersil.com/products/deviceinfo.asp?pn=ISL9000 ___ 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.
