I have a question for the group. I was looking at an article for building an ultra-low noise voltage reference by Walt Jung, published in Electronic Design June 24, 1993 and a URL to the article is below. I want to filter the output of an LTZ1000 based 10V reference I am building and this circuit has a very low freq corner of 1.6 Hz. I was concerned about the leakage through R1-C1. If C1 had as little as 1ua leakage, it would drop the voltage through R1 by 1 mV. The spec on 100 uF electrolytic and tantalum capacitors show a leakage of 20 ua at rated voltage so this could be of great concern. However, at the low few tenths of a volt that should be across C1, the capacitor should have a much lower leakage amount, which is the theme of the article. To get a better appreciation of the issue, I connected a precision 0 to 10 V source (100uV resolution steps) to a series combination of a 1 Kohm resistor and a 100 uF electrolytic and, later, another 47uF tantalum and a 47 uF electrolytic capacitor. In all cases the leakage, as measured with a Keithley 414 picoammmeter, showed a leakage or around 0.08 uA at 10V and varying 0.04 to 0.12 uA, around .1uA at 1V and varying , and around 1 pA at 0.1V, but with widely varying leakage current of 0.5 to 1.5 pA, with occasional peaks of -0.5 to 2 pA. This would equate to about +/- 2 uV voltage variation across R1, making a 10 V 0.1ppm stable voltage reference of questionable value. I also tried a 0.68 uF polystyrene capacitor and also saw leakage current variations, although much less than the electrolytic and tantalum capacitors, as one would expect. Thinking the problem might be the the picoammeter, I put a 100 megohm 0.1% precision resistor in place of the capacitor across the precision voltage source set for 0.1 V and measured the current through the resistor at a very stable 0.9 pA on the Keithley 414 (sb 1pA but accurate enough for my measurements - the resistor shielded box likely has some sub pA leakage also). Note that I used shielded cables for all measurements, and the resistor and capacitor were in a shielded box, as well as the 100 Mohm calibration resistor. Touching the cables or boxes did not change the picoammeter reading at all, indicating to me that the shielding was reasonable. I suppose the best approach is to build it and characterize it, but it's not fruitful if someone has already done this. So my question is: has anyone built this circuit and characterized it, particularly over temperature for stability at the sub ppm level? Thanks, Randall Evans http://waltjung.org/PDFs/Build_Ultra_Low_Noise_Voltage_Reference.pdf

-------- In message <CANwu9JY-_o80YoeN_-hnXFxsYuQ=VKON0yw_RoovEGjhh3hHSA@mail.gmail.com> , Randy Evans writes: >I was concerned about the leakage through R1-C1. Ideally there should not be any voltage across C1 because C2 "bootstraps" it, so C1's leakage resistance should not matter at all. >In all cases the leakage, as measured with a >Keithley 414 picoammmeter, showed a leakage or around 0.08 uA at 10V That kind of currents take you into the territory where there are no insulators, only conductors which are not very good at it, such as expoxy, air, humidity, fingerprints etc. The very first thing you want to do, is wash your entire construction in isopropanol[1]. The next thing you want to do is make sure you are not fighting a an electrostatic phenomena: Only measure inside a grounded metal enclosure. Cookie tins work great. Finally make sure you are not measuring Seebeck/thermo-electric phenomena: Measure while you raise and lower the temperature of the hole thing and look for gradients. >I also tried a 0.68 uF polystyrene capacitor and also saw leakage current >variations, although much less than the electrolytic and tantalum >capacitors, as one would expect. I actually have in mind to buy a couple of the cheapest "teflon" capactors from the audiohomøopathy world, and see if that is really what it claims to be. Poul-Henning [1] I've been told that the liquid used in dishwashers to avoid spots on glass, a mixture of soaps and alcohols, is also good for electronics, but I have not tried it. -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 phk@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.

Yes I have relevant experience with Lifters, fingerprints generally are a nightmare. May also be worth mentioning that different grades of IPA are more or less useful, it absorbs water in its pure form so this needs to be taken into account. Use "no clean" fluxed solder if possible as it works well. Also relevant, don't forget that NASA like using splice joints where the wire is tied into essentially a reef knot. This is for all sorts of reasons not least visual inspection of the joint at regular intervals and anti- vibration measures are used like clear heatshrink. ________________________________________ From: volt-nuts <volt-nuts-bounces@febo.com> on behalf of Poul-Henning Kamp <phk@phk.freebsd.dk> Sent: 17 February 2018 09:10 To: Discussion of precise voltage measurement; Randy Evans Subject: Re: [volt-nuts] Low noise reference -------- In message <CANwu9JY-_o80YoeN_-hnXFxsYuQ=VKON0yw_RoovEGjhh3hHSA@mail.gmail.com> , Randy Evans writes: >I was concerned about the leakage through R1-C1. Ideally there should not be any voltage across C1 because C2 "bootstraps" it, so C1's leakage resistance should not matter at all. >In all cases the leakage, as measured with a >Keithley 414 picoammmeter, showed a leakage or around 0.08 uA at 10V That kind of currents take you into the territory where there are no insulators, only conductors which are not very good at it, such as expoxy, air, humidity, fingerprints etc. The very first thing you want to do, is wash your entire construction in isopropanol[1]. The next thing you want to do is make sure you are not fighting a an electrostatic phenomena: Only measure inside a grounded metal enclosure. Cookie tins work great. Finally make sure you are not measuring Seebeck/thermo-electric phenomena: Measure while you raise and lower the temperature of the hole thing and look for gradients. >I also tried a 0.68 uF polystyrene capacitor and also saw leakage current >variations, although much less than the electrolytic and tantalum >capacitors, as one would expect. I actually have in mind to buy a couple of the cheapest "teflon" capactors from the audiohomøopathy world, and see if that is really what it claims to be. Poul-Henning [1] I've been told that the liquid used in dishwashers to avoid spots on glass, a mixture of soaps and alcohols, is also good for electronics, but I have not tried it. -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 phk@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. _______________________________________________ volt-nuts mailing list -- volt-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts and follow the instructions there.

also see https://workmanship.nasa.gov/lib/insp/2%20books/links/sections/407%20Splices.html -Andre ________________________________________ From: volt-nuts <volt-nuts-bounces@febo.com> on behalf of Randy Evans <randyevans2688@gmail.com> Sent: 16 February 2018 18:39 To: Discussion of precise voltage measurement Subject: [volt-nuts] Low noise reference I have a question for the group. I was looking at an article for building an ultra-low noise voltage reference by Walt Jung, published in Electronic Design June 24, 1993 and a URL to the article is below. I want to filter the output of an LTZ1000 based 10V reference I am building and this circuit has a very low freq corner of 1.6 Hz. I was concerned about the leakage through R1-C1. If C1 had as little as 1ua leakage, it would drop the voltage through R1 by 1 mV. The spec on 100 uF electrolytic and tantalum capacitors show a leakage of 20 ua at rated voltage so this could be of great concern. However, at the low few tenths of a volt that should be across C1, the capacitor should have a much lower leakage amount, which is the theme of the article. To get a better appreciation of the issue, I connected a precision 0 to 10 V source (100uV resolution steps) to a series combination of a 1 Kohm resistor and a 100 uF electrolytic and, later, another 47uF tantalum and a 47 uF electrolytic capacitor. In all cases the leakage, as measured with a Keithley 414 picoammmeter, showed a leakage or around 0.08 uA at 10V and varying 0.04 to 0.12 uA, around .1uA at 1V and varying , and around 1 pA at 0.1V, but with widely varying leakage current of 0.5 to 1.5 pA, with occasional peaks of -0.5 to 2 pA. This would equate to about +/- 2 uV voltage variation across R1, making a 10 V 0.1ppm stable voltage reference of questionable value. I also tried a 0.68 uF polystyrene capacitor and also saw leakage current variations, although much less than the electrolytic and tantalum capacitors, as one would expect. Thinking the problem might be the the picoammeter, I put a 100 megohm 0.1% precision resistor in place of the capacitor across the precision voltage source set for 0.1 V and measured the current through the resistor at a very stable 0.9 pA on the Keithley 414 (sb 1pA but accurate enough for my measurements - the resistor shielded box likely has some sub pA leakage also). Note that I used shielded cables for all measurements, and the resistor and capacitor were in a shielded box, as well as the 100 Mohm calibration resistor. Touching the cables or boxes did not change the picoammeter reading at all, indicating to me that the shielding was reasonable. I suppose the best approach is to build it and characterize it, but it's not fruitful if someone has already done this. So my question is: has anyone built this circuit and characterized it, particularly over temperature for stability at the sub ppm level? Thanks, Randall Evans http://waltjung.org/PDFs/Build_Ultra_Low_Noise_Voltage_Reference.pdf _______________________________________________ volt-nuts mailing list -- volt-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts and follow the instructions there.

Thanks for the feedback. I don't think I am having problems with leakage in the test setup, thermal, or shielding issues. I used aluminum cast boxes (Pomona 2391) which have BNC M and F connectors, which use teflon insulators. The cast boxes have enough thermal mass and not subject to moving air currents, so it is unlikely that the wide voltage extremes, over periods of a few to 10's of milliseconds, I am seeing are due to thermal changes. Also, I had a typo in the original message (I said pA when I meant to type nA) in that the last sentence in the second paragraph should read: "and around 1 nA at 0.1V, but with widely varying leakage current of 0.5 to 1.5 nA, with occasional peaks of -0.5 to 2 nA. This would equate to about +/- 2 uV voltage variation across R1, making a 10 V 0.1ppm stable voltage reference of questionable value." the first sentence in the fourth paragraph should also be referencing nA's. Sorry about the brain lapse. The wide variations in current through the 100uF cap-1Kohm resistor are my main concern since I can't explain it. It is absolutely not present in the 100 Mohm cal resistor in the same type aluminum cast box and is completely stable. I originally suspected interference but the cap-resistor and calibration resistor are mounted in identical shielded boxes but the 100 Mohm cal resistor is clean and stable. I suppose I need to bite the bullet and build the circuit and see how stable it is. I can check it with my two Fluke 732As and two HP-3458As. Rrandall Evans On Sat, Feb 17, 2018 at 4:38 AM, Andre <Andre@lanoe.net> wrote: > also see https://workmanship.nasa.gov/lib/insp/2%20books/links/ > sections/407%20Splices.html > > -Andre > > ________________________________________ > From: volt-nuts <volt-nuts-bounces@febo.com> on behalf of Randy Evans < > randyevans2688@gmail.com> > Sent: 16 February 2018 18:39 > To: Discussion of precise voltage measurement > Subject: [volt-nuts] Low noise reference > > I have a question for the group. I was looking at an article for building > an ultra-low noise voltage reference by Walt Jung, published in Electronic > Design June 24, 1993 and a URL to the article is below. I want to filter > the output of an LTZ1000 based 10V reference I am building and this circuit > has a very low freq corner of 1.6 Hz. I was concerned about the leakage > through R1-C1. If C1 had as little as 1ua leakage, it would drop the > voltage through R1 by 1 mV. The spec on 100 uF electrolytic and tantalum > capacitors show a leakage of 20 ua at rated voltage so this could be of > great concern. However, at the low few tenths of a volt that should be > across C1, the capacitor should have a much lower leakage amount, which is > the theme of the article. > > To get a better appreciation of the issue, I connected a precision 0 to 10 > V source (100uV resolution steps) to a series combination of a 1 Kohm > resistor and a 100 uF electrolytic and, later, another 47uF tantalum and a > 47 uF electrolytic capacitor. In all cases the leakage, as measured with a > Keithley 414 picoammmeter, showed a leakage or around 0.08 uA at 10V and > varying 0.04 to 0.12 uA, around .1uA at 1V and varying , and around 1 pA at > 0.1V, but with widely varying leakage current of 0.5 to 1.5 pA, with > occasional peaks of -0.5 to 2 pA. This would equate to about +/- 2 uV > voltage variation across R1, making a 10 V 0.1ppm stable voltage reference > of questionable value. > > I also tried a 0.68 uF polystyrene capacitor and also saw leakage current > variations, although much less than the electrolytic and tantalum > capacitors, as one would expect. > > Thinking the problem might be the the picoammeter, I put a 100 megohm 0.1% > precision resistor in place of the capacitor across the precision voltage > source set for 0.1 V and measured the current through the resistor at a > very stable 0.9 pA on the Keithley 414 (sb 1pA but accurate enough for my > measurements - the resistor shielded box likely has some sub pA leakage > also). Note that I used shielded cables for all measurements, and the > resistor and capacitor were in a shielded box, as well as the 100 Mohm > calibration resistor. Touching the cables or boxes did not change the > picoammeter reading at all, indicating to me that the shielding was > reasonable. > > I suppose the best approach is to build it and characterize it, but it's > not fruitful if someone has already done this. So my question is: has > anyone built this circuit and characterized it, particularly over > temperature for stability at the sub ppm level? > > Thanks, > > Randall Evans > > > > > > > > http://waltjung.org/PDFs/Build_Ultra_Low_Noise_Voltage_Reference.pdf > _______________________________________________ > volt-nuts mailing list -- volt-nuts@febo.com > To unsubscribe, go to https://www.febo.com/cgi-bin/ > mailman/listinfo/volt-nuts > and follow the instructions there. > > _______________________________________________ > volt-nuts mailing list -- volt-nuts@febo.com > To unsubscribe, go to https://www.febo.com/cgi-bin/ > mailman/listinfo/volt-nuts > and follow the instructions there. >

Hello, Are you familiar with the 2DW232, a Chinese zener? There is one particular factory in China which is somehow producing exceptionally low noise units (much lower noise than the LTZ1000). There is an EEVBlog forum member who lives in China and has graciously volunteered to perform group buys from this factory and then distribute the pets to the individual buyers. Sent from my iPhone > On Feb 17, 2018, at 9:07 AM, Randy Evans <randyevans2688@gmail.com> wrote: > > Thanks for the feedback. I don't think I am having problems with leakage > in the test setup, thermal, or shielding issues. I used aluminum cast > boxes (Pomona 2391) which have BNC M and F connectors, which use teflon > insulators. The cast boxes have enough thermal mass and not subject to > moving air currents, so it is unlikely that the wide voltage extremes, over > periods of a few to 10's of milliseconds, I am seeing are due to thermal > changes. Also, I had a typo in the original message (I said pA when I > meant to type nA) in that the last sentence in the second paragraph should > read: "and around 1 nA at 0.1V, but with widely varying leakage current of > 0.5 to 1.5 nA, with occasional peaks of -0.5 to 2 nA. This would equate to > about +/- 2 uV voltage variation across R1, making a 10 V 0.1ppm stable > voltage reference of questionable value." the first sentence in the fourth > paragraph should also be referencing nA's. Sorry about the brain lapse. > > The wide variations in current through the 100uF cap-1Kohm resistor are my > main concern since I can't explain it. It is absolutely not present in the > 100 Mohm cal resistor in the same type aluminum cast box and is completely > stable. I originally suspected interference but the cap-resistor and > calibration resistor are mounted in identical shielded boxes but the 100 > Mohm cal resistor is clean and stable. > > I suppose I need to bite the bullet and build the circuit and see how > stable it is. I can check it with my two Fluke 732As and two HP-3458As. > > Rrandall Evans > > >> On Sat, Feb 17, 2018 at 4:38 AM, Andre <Andre@lanoe.net> wrote: >> >> also see https://workmanship.nasa.gov/lib/insp/2%20books/links/ >> sections/407%20Splices.html >> >> -Andre >> >> ________________________________________ >> From: volt-nuts <volt-nuts-bounces@febo.com> on behalf of Randy Evans < >> randyevans2688@gmail.com> >> Sent: 16 February 2018 18:39 >> To: Discussion of precise voltage measurement >> Subject: [volt-nuts] Low noise reference >> >> I have a question for the group. I was looking at an article for building >> an ultra-low noise voltage reference by Walt Jung, published in Electronic >> Design June 24, 1993 and a URL to the article is below. I want to filter >> the output of an LTZ1000 based 10V reference I am building and this circuit >> has a very low freq corner of 1.6 Hz. I was concerned about the leakage >> through R1-C1. If C1 had as little as 1ua leakage, it would drop the >> voltage through R1 by 1 mV. The spec on 100 uF electrolytic and tantalum >> capacitors show a leakage of 20 ua at rated voltage so this could be of >> great concern. However, at the low few tenths of a volt that should be >> across C1, the capacitor should have a much lower leakage amount, which is >> the theme of the article. >> >> To get a better appreciation of the issue, I connected a precision 0 to 10 >> V source (100uV resolution steps) to a series combination of a 1 Kohm >> resistor and a 100 uF electrolytic and, later, another 47uF tantalum and a >> 47 uF electrolytic capacitor. In all cases the leakage, as measured with a >> Keithley 414 picoammmeter, showed a leakage or around 0.08 uA at 10V and >> varying 0.04 to 0.12 uA, around .1uA at 1V and varying , and around 1 pA at >> 0.1V, but with widely varying leakage current of 0.5 to 1.5 pA, with >> occasional peaks of -0.5 to 2 pA. This would equate to about +/- 2 uV >> voltage variation across R1, making a 10 V 0.1ppm stable voltage reference >> of questionable value. >> >> I also tried a 0.68 uF polystyrene capacitor and also saw leakage current >> variations, although much less than the electrolytic and tantalum >> capacitors, as one would expect. >> >> Thinking the problem might be the the picoammeter, I put a 100 megohm 0.1% >> precision resistor in place of the capacitor across the precision voltage >> source set for 0.1 V and measured the current through the resistor at a >> very stable 0.9 pA on the Keithley 414 (sb 1pA but accurate enough for my >> measurements - the resistor shielded box likely has some sub pA leakage >> also). Note that I used shielded cables for all measurements, and the >> resistor and capacitor were in a shielded box, as well as the 100 Mohm >> calibration resistor. Touching the cables or boxes did not change the >> picoammeter reading at all, indicating to me that the shielding was >> reasonable. >> >> I suppose the best approach is to build it and characterize it, but it's >> not fruitful if someone has already done this. So my question is: has >> anyone built this circuit and characterized it, particularly over >> temperature for stability at the sub ppm level? >> >> Thanks, >> >> Randall Evans >> >> >> >> >> >> >> >> http://waltjung.org/PDFs/Build_Ultra_Low_Noise_Voltage_Reference.pdf >> _______________________________________________ >> volt-nuts mailing list -- volt-nuts@febo.com >> To unsubscribe, go to https://www.febo.com/cgi-bin/ >> mailman/listinfo/volt-nuts >> and follow the instructions there. >> >> _______________________________________________ >> volt-nuts mailing list -- volt-nuts@febo.com >> To unsubscribe, go to https://www.febo.com/cgi-bin/ >> mailman/listinfo/volt-nuts >> and follow the instructions there. >> > _______________________________________________ > volt-nuts mailing list -- volt-nuts@febo.com > To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts > and follow the instructions there.

Apologies, the last message went out before I was finished drafting it. See these links: https://www.eevblog.com/forum/metrology/ultra-low-noise-reference-2dw232-2dw233-2dw23x/ https://www.eevblog.com/forum/metrology/factory-2dw23x-order-aggregation-thread/ Note that these zeners are quite cheap. You could parallel a number of them for ever further noise reduction, yet still be cheaper than an LTZ. Sent from my iPhone > On Feb 17, 2018, at 7:24 PM, jasonpepas@gmail.com wrote: > > Hello, > > Are you familiar with the 2DW232, a Chinese zener? There is one particular factory in China which is somehow producing exceptionally low noise units (much lower noise than the LTZ1000). > > There is an EEVBlog forum member who lives in China and has graciously volunteered to perform group buys from this factory and then distribute the pets to the individual buyers. > > > > Sent from my iPhone > >> On Feb 17, 2018, at 9:07 AM, Randy Evans <randyevans2688@gmail.com> wrote: >> >> Thanks for the feedback. I don't think I am having problems with leakage >> in the test setup, thermal, or shielding issues. I used aluminum cast >> boxes (Pomona 2391) which have BNC M and F connectors, which use teflon >> insulators. The cast boxes have enough thermal mass and not subject to >> moving air currents, so it is unlikely that the wide voltage extremes, over >> periods of a few to 10's of milliseconds, I am seeing are due to thermal >> changes. Also, I had a typo in the original message (I said pA when I >> meant to type nA) in that the last sentence in the second paragraph should >> read: "and around 1 nA at 0.1V, but with widely varying leakage current of >> 0.5 to 1.5 nA, with occasional peaks of -0.5 to 2 nA. This would equate to >> about +/- 2 uV voltage variation across R1, making a 10 V 0.1ppm stable >> voltage reference of questionable value." the first sentence in the fourth >> paragraph should also be referencing nA's. Sorry about the brain lapse. >> >> The wide variations in current through the 100uF cap-1Kohm resistor are my >> main concern since I can't explain it. It is absolutely not present in the >> 100 Mohm cal resistor in the same type aluminum cast box and is completely >> stable. I originally suspected interference but the cap-resistor and >> calibration resistor are mounted in identical shielded boxes but the 100 >> Mohm cal resistor is clean and stable. >> >> I suppose I need to bite the bullet and build the circuit and see how >> stable it is. I can check it with my two Fluke 732As and two HP-3458As. >> >> Rrandall Evans >> >> >>> On Sat, Feb 17, 2018 at 4:38 AM, Andre <Andre@lanoe.net> wrote: >>> >>> also see https://workmanship.nasa.gov/lib/insp/2%20books/links/ >>> sections/407%20Splices.html >>> >>> -Andre >>> >>> ________________________________________ >>> From: volt-nuts <volt-nuts-bounces@febo.com> on behalf of Randy Evans < >>> randyevans2688@gmail.com> >>> Sent: 16 February 2018 18:39 >>> To: Discussion of precise voltage measurement >>> Subject: [volt-nuts] Low noise reference >>> >>> I have a question for the group. I was looking at an article for building >>> an ultra-low noise voltage reference by Walt Jung, published in Electronic >>> Design June 24, 1993 and a URL to the article is below. I want to filter >>> the output of an LTZ1000 based 10V reference I am building and this circuit >>> has a very low freq corner of 1.6 Hz. I was concerned about the leakage >>> through R1-C1. If C1 had as little as 1ua leakage, it would drop the >>> voltage through R1 by 1 mV. The spec on 100 uF electrolytic and tantalum >>> capacitors show a leakage of 20 ua at rated voltage so this could be of >>> great concern. However, at the low few tenths of a volt that should be >>> across C1, the capacitor should have a much lower leakage amount, which is >>> the theme of the article. >>> >>> To get a better appreciation of the issue, I connected a precision 0 to 10 >>> V source (100uV resolution steps) to a series combination of a 1 Kohm >>> resistor and a 100 uF electrolytic and, later, another 47uF tantalum and a >>> 47 uF electrolytic capacitor. In all cases the leakage, as measured with a >>> Keithley 414 picoammmeter, showed a leakage or around 0.08 uA at 10V and >>> varying 0.04 to 0.12 uA, around .1uA at 1V and varying , and around 1 pA at >>> 0.1V, but with widely varying leakage current of 0.5 to 1.5 pA, with >>> occasional peaks of -0.5 to 2 pA. This would equate to about +/- 2 uV >>> voltage variation across R1, making a 10 V 0.1ppm stable voltage reference >>> of questionable value. >>> >>> I also tried a 0.68 uF polystyrene capacitor and also saw leakage current >>> variations, although much less than the electrolytic and tantalum >>> capacitors, as one would expect. >>> >>> Thinking the problem might be the the picoammeter, I put a 100 megohm 0.1% >>> precision resistor in place of the capacitor across the precision voltage >>> source set for 0.1 V and measured the current through the resistor at a >>> very stable 0.9 pA on the Keithley 414 (sb 1pA but accurate enough for my >>> measurements - the resistor shielded box likely has some sub pA leakage >>> also). Note that I used shielded cables for all measurements, and the >>> resistor and capacitor were in a shielded box, as well as the 100 Mohm >>> calibration resistor. Touching the cables or boxes did not change the >>> picoammeter reading at all, indicating to me that the shielding was >>> reasonable. >>> >>> I suppose the best approach is to build it and characterize it, but it's >>> not fruitful if someone has already done this. So my question is: has >>> anyone built this circuit and characterized it, particularly over >>> temperature for stability at the sub ppm level? >>> >>> Thanks, >>> >>> Randall Evans >>> >>> >>> >>> >>> >>> >>> >>> http://waltjung.org/PDFs/Build_Ultra_Low_Noise_Voltage_Reference.pdf >>> _______________________________________________ >>> volt-nuts mailing list -- volt-nuts@febo.com >>> To unsubscribe, go to https://www.febo.com/cgi-bin/ >>> mailman/listinfo/volt-nuts >>> and follow the instructions there. >>> >>> _______________________________________________ >>> volt-nuts mailing list -- volt-nuts@febo.com >>> To unsubscribe, go to https://www.febo.com/cgi-bin/ >>> mailman/listinfo/volt-nuts >>> and follow the instructions there. >>> >> _______________________________________________ >> volt-nuts mailing list -- volt-nuts@febo.com >> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts >> and follow the instructions there.