Re: Resistance standard/reference design / DIY
Frank, Very useful feedback. I think going P-to-P (instead of PCB) with this makes a?lot of sense. Makes the project go faster too!? I was thinking about Z201 resistors - why doesn't anyone seem to use these? They're the best combo %+ppm I can find at the typical US suppliers. They're also not quite an arm and a leg (maybe a couple of fingers...).? If/when I have a kit built, I'm thinking of sending it to a local metrology lab (being in Southern California, if there's something plentiful around is labs, instruments, and cal shops... ;)).? Thank you, Radu.?
Hello,
This is my design for a 10k reference resistor.
It's based on a 9k9990 VHP202Z, plus a Thin Film resistor as a fixed trim. But I would recommend a 10k VHP101 instead.
It's sitting in a aluminum block, and this block is tightly attached to an aluminum case.
A precision NTC measures its temperature, so you can at first determine the R(T) curve and always precisely calculate its actual resistance at a given external temperature.
I omitted a PCB, due to leakage current, which created errors on the order of several 10 ppm.
The binding posts should be Pomona CuTe type 3770, as these have high isolation resistance, and low e.m.f..
If you use a DMMs with offset compensation, the binding posts can be of lower quality.?
4W Kelvin connection is required.
This assembly is good for 1ppm/year stability, real T.C. from 0.3 to 1 ppm/K (I got 5 of these), and a drift predictability meanwhile of < 0.2ppm.
So these can be used for calibration of a 3458A.
If you need other reference resistors, you'd need equivalent assemblies, but also transfer standards.
Frank
? ?
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Re: Resistance standard/reference design / DIY
Hello,
This is my design for a 10k reference resistor.
It's based on a 9k9990 VHP202Z, plus a Thin Film resistor as a fixed trim. But I would recommend a 10k VHP101 instead.
It's sitting in a aluminum block, and this block is tightly attached to an aluminum case.
A precision NTC measures its temperature, so you can at first determine the R(T) curve and always precisely calculate its actual resistance at a given external temperature.
I omitted a PCB, due to leakage current, which created errors on the order of several 10 ppm.
The binding posts should be Pomona CuTe type 3770, as these have high isolation resistance, and low e.m.f..
If you use a DMMs with offset compensation, the binding posts can be of lower quality.?
4W Kelvin connection is required.
This assembly is good for 1ppm/year stability, real T.C. from 0.3 to 1 ppm/K (I got 5 of these), and a drift predictability meanwhile of < 0.2ppm.
So these can be used for calibration of a 3458A.
If you need other reference resistors, you'd need equivalent assemblies, but also transfer standards.
Frank
? ?
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Re: Precision Voltage Reference
Well,
in the past there was only one reasonable 10V voltage reference from Joe Geller, the SVR-T.
It was very stable over time, temperature and humidity and could be used as a starting reference point when you also had a transfer standard available.
It was stable to about 5ppm in all parameters, because it used a hermetic, ceramic package, based on the AD587UQ or LQ, if I remember correctly, and it was calibrated against a 3458A.
In this sense, it could really be used for metrology / calibration purposes. But these hermetic ICs are obsolete, as well as Joe Geller does not offer these references any more.
I attach a picture of a re-build, w/o the T.C. compensation by Lars Walenius.
All other such references are simply toys, I guess, and some are even hoaxes, so please pay attention.
Maybe the CheckDMM can be regarded as a reasonably stable reference, but he himself declares it as a (sanity) checker only, not as device for calibrating anything.?
It covers a few modes / ranges only, so it's not very handy, I think. Another problem for you is, that a resistive 10:1 divider wouldn't help you, as your DMMs probably have 10MOhm input resistance only, spoiling the divider ratio.
In general, calibrating any DMM requires to compare all ranges and all modes to a known good and stable reference standard, anything else is useless.
If you want to fully check or even adjust your DMM at home, I fear that you'll directly fall for volt-nuts passion.
There are very good DIY 10V references out there, on eevblog, based on either the much more stable LM399, or even based on the LTZ1000, all have to be calibrated against a good other reference.
As said, you would also need transfer standards for 1V, 100mV and 100 / 1000V to make a proper calibration of DCV alone.
Frank??
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Re: Resistance standard/reference design / DIY
I have an ESI 8 1/2 digit ohm meter. I measured my Leeds & Northrup 10K reference on a freshly calibrated 3458.
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Re: Precision Voltage Reference
Typo, obviously "you need a calibration". Not an intervention ?
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Re: Resistance standard/reference design / DIY
There is another option if the goal is to make a presicion 1/2 voltage divider or *2 multiplier.
Rather than selecting and matching 0.005% bulk metal foil resistors (which cost ~$5.00 each),
one can use a Linear Technologies (now Analog Devices) LTC1043. One device, with a few
capacitors (4 of which should be high quality) can be configured to make both a 1/2 divider
(1 ppm) and a 2* (5 ppm) multiplier per the application information on the data sheet? at the same
or lower cost.
The ultimate accuracy probably depends on the quality of the operational amplifier(s) the circuit.
Stephen Menasian?
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Re: Resistance standard/reference design / DIY
Jeff, Interestingly, this reminds me I have an MAX6225ACPA little kit I put together some years ago for purposes such as this. I also placed a resistive divider on there to add an 185mV output... The 2.500V shows as a 2.5002V, which is a pretty nicely trimmed reference, within the spec by an order of magnitude.? Thank you for the info above.?
Though I'd find it hard to resist using .005%+.2ppm resistors for something like?this, as David puts it, it's useful calculating exactly how much of that is really needed for a certain instrument?(vs. overkill). For instance, for the 8502A, the 100ohm accuracy is listed as?+-.002?+ 2 ("% of input?+ no. of digits"). Can anyone help decipher?this? I have a .005%+.2ppm bulk Z foil on a cart which I could have by some time next week and am wondering how that'd do with this.
Thank you, Radu.?
The Analog Devices AD584 offers 4 reference voltages, 2.500, 5.000, 7.500, 10.000V
15 ppm/¡ãC Max, 0¡ãC to 70¡ãC (AD584K)
15 ppm/¡ãC Max, -55¡ãC to +125¡ãC (AD584T)
I¡¯ve ordered products from Electronic Goldmine 5 or 6 times with no problems. I have no relationship with them other then as a customer.
Electronic Goldmine offers:
, $4.95
G20756 - Bulk Metal® Foil Technology Super Precision Calibration Resistor
$8.00 ¡À 0.05%?Rated 2¦¸ at 8Watt (if placed on heat sink).
$8.00
$4.95
?
Their stock changes daily, so check back often.
I picked up other 0.01% and 0.001% resistors and a 0.1% 0.1uF capacitor.
?
There are a plethora of ¡®precision voltage references¡¯ on Amazon and Ebay.
?
As others have said, what level of precision you need depends on what you are doing.
I suspect the DMMplus is a lot more accurate then I will ever need, but the price was right and I can now trust my meters aren¡¯t lying to me.
My brother in law has a Fluke that is way out of calibration, so quality of build is no assurance of staying within specs, he's decided it isn't worth repairing and bought a cheap DVM from Harbor Freight that wss accurate to better then 0.1%. Plenty accuracy for checking farm equipment electrical systems..
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Re: Resistance standard/reference design / DIY
I was also thinking of making a resistance "standard" for myself that would help calibrate my impedance analyzer (that I posted to this group in the past). The main reasons I want to make my own is to have a BNC 4 wire connector so the contact resistance effects are minimized (or at least consistent), and so that I can pick and choose which values to use. My initial board design is here (, schematic/board images below). With <15ppm resistors (and assuming reasonable room temperatures), I'd think this is sufficient for my application (~0.1% or so), but would happily take suggestions. Although, if you're considering thermal mass/inertia of the traces I'm guessing this is insufficient for you.? ?  
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Re: Resistance standard/reference design / DIY
I think such a project would be useful for your typical "highly invested" hobbyists like me, for which I think a 6.5 digit DMM is pretty normative. In my case, my workhorse is a Fluke 8840A (5.5), and I also have a Fluke 8502A which gets me to 6.5 digits. I don't see myself going 7.5 any time soon unless the bug bites a good chunk of me.? Radu.?
On Thu, Dec 15, 2022 at 2:37 PM Dr. David Kirkby, Kirkby Microwave Ltd < drkirkby@...> wrote: On Thu, 15 Dec 2022 at 20:18, Radu Bogdan Dicher < vondicher@...> wrote: Hi all,
I thought this may be worth its own thread. Definitely spun off of a "WTB" post which has its purpose, but an alternate approach would be to build something at DIY level and expected use/requirements.?
This regards putting together a little kit, or possibly a PCB with Z bulk foils and some sort of posts for the probes, in order to create a homebrew bench resistor standard.
Would love to hear thoughts on the requirements for such a kit or board. A couple of quick thoughts would be thick copper traces, short runs, and some sort of consideration for thermal mass/inertia and such for good stability (enclosure? cooling?). Maybe even a temperature sensor with some readout for monitoring.?
Thank you for pitching in your thoughts.?
Radu.?
What use are you going to put this to? You really need to think about what uncerties you can tolerate. Is it for checking 3.5 digit multimeters, or calibrating 8.5 digit ones?
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Re: Resistance standard/reference design / DIY
On Thu, 15 Dec 2022 at 20:18, Radu Bogdan Dicher < vondicher@...> wrote: Hi all,
I thought this may be worth its own thread. Definitely spun off of a "WTB" post which has its purpose, but an alternate approach would be to build something at DIY level and expected use/requirements.?
This regards putting together a little kit, or possibly a PCB with Z bulk foils and some sort of posts for the probes, in order to create a homebrew bench resistor standard.
Would love to hear thoughts on the requirements for such a kit or board. A couple of quick thoughts would be thick copper traces, short runs, and some sort of consideration for thermal mass/inertia and such for good stability (enclosure? cooling?). Maybe even a temperature sensor with some readout for monitoring.?
Thank you for pitching in your thoughts.?
Radu.?
What use are you going to put this to? You really need to think about what uncerties you can tolerate. Is it for checking 3.5 digit multimeters, or calibrating 8.5 digit ones?
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Resistance standard/reference design / DIY
Hi all, I thought this may be worth its own thread. Definitely spun off of a "WTB" post which has its purpose, but an alternate approach would be to build something at DIY level and expected use/requirements.?
This regards putting together a little kit, or possibly a PCB with Z bulk foils and some sort of posts for the probes, in order to create a homebrew bench resistor standard.
Would love to hear thoughts on the requirements for such a kit or board. A couple of quick thoughts would be thick copper traces, short runs, and some sort of consideration for thermal mass/inertia and such for good stability (enclosure? cooling?). Maybe even a temperature sensor with some readout for monitoring.?
Thank you for pitching in your thoughts.?
Radu.?
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Re: Precision Voltage Reference
You need a JVS:
--
Prof. Thomas H. Lee
Allen Ctr., Rm. 205
420 Via Palou Mall
Stanford University
Stanford, CA 94305-4070
On 12/15/2022 11:24, Adrian Godwin
wrote:
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Do I need an
intervention?
?
I think you need a celebration.
?
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Re: Precision Voltage Reference
Do I need an intervention?
?
I think you need a celebration. ?
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Re: Precision Voltage Reference
Huh? Don¡¯t know anything about that¡ ?
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From: [email protected] < [email protected]> On Behalf Of nigel adams via groups.io Sent: Wednesday, December 14, 2022 9:31 AM To: [email protected]Subject: Re: [Test Equipment Design & Construction] Precision Voltage Reference ? No, BBC Radio 4 actually¡ ? ? ? ±á³¾³¾³¾¡. ? Dilbert right? ? What would Dilbert think are the necessary precision Nail characteristics to revise the new Power Supply design anyway? Would he consider that he needs a higher precision Nail? And of what tolerance and repeatability? ? What characteristics do the wood need to meet to maintain those Nail characteristics over time and environmental constraints? ? Surely, he would have to consider all of these critical parameters before presenting this new Power Supply design to his boss who wouldn¡¯t understand anyway. Maybe Catbert would though. ? Ross ? ? ? ? Not going for anything with precision then.... ???Ho Ho, Merry Christmas. by banging a nail into a piece of wood... I am not in denial...?? I can quit calibrating equipment any time I want.???????? I just don't want to right now...
...and don't worry about sending me any nice precision resistor, just a plain junkbox 0.001%? resistor with a ¡À0.2ppm/¡ãC tempco would be fine. I can get by with that.
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Re: Precision Voltage Reference
No, BBC Radio 4 actually¡ ? ?
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From: [email protected] <[email protected]> On Behalf Of si_emi_01
Sent: 14 December 2022 16:25
To: [email protected]
Subject: Re: [Test Equipment Design & Construction] Precision Voltage Reference? ±á³¾³¾³¾¡. ? Dilbert right? ? What would Dilbert think are the necessary precision Nail characteristics to revise the new Power Supply design anyway? Would he consider that he needs a higher precision Nail? And of what tolerance and repeatability? ? What characteristics do the wood need to meet to maintain those Nail characteristics over time and environmental constraints? ? Surely, he would have to consider all of these critical parameters before presenting this new Power Supply design to his boss who wouldn¡¯t understand anyway. Maybe Catbert would though. ? Ross ? ? ? ? Not going for anything with precision then.... ???Ho Ho, Merry Christmas. by banging a nail into a piece of wood... I am not in denial...?? I can quit calibrating equipment any time I want.???????? I just don't want to right now...
...and don't worry about sending me any nice precision resistor, just a plain junkbox 0.001%? resistor with a ¡À0.2ppm/¡ãC tempco would be fine. I can get by with that.
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Re: Precision Voltage Reference
±á³¾³¾³¾¡. ? Dilbert right? ? What would Dilbert think are the necessary precision Nail characteristics to revise the new Power Supply design anyway? Would he consider that he needs a higher precision Nail? And of what tolerance and repeatability? ? What characteristics do the wood need to meet to maintain those Nail characteristics over time and environmental constraints? ? Surely, he would have to consider all of these critical parameters before presenting this new Power Supply design to his boss who wouldn¡¯t understand anyway. Maybe Catbert would though. ? Ross ? ? ?
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From: [email protected] < [email protected]> On Behalf Of nigel adams via groups.io Sent: Wednesday, December 14, 2022 12:16 AM To: [email protected]Subject: Re: [Test Equipment Design & Construction] Precision Voltage Reference ? Not going for anything with precision then.... ???Ho Ho, Merry Christmas. by banging a nail into a piece of wood... I am not in denial...?? I can quit calibrating equipment any time I want.???????? I just don't want to right now...
...and don't worry about sending me any nice precision resistor, just a plain junkbox 0.001%? resistor with a ¡À0.2ppm/¡ãC tempco would be fine. I can get by with that.
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Re: Precision Voltage Reference
Not going for anything with precision then.... ???Ho Ho, Merry Christmas. by banging a nail into a piece of wood...
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On 14 Dec 2022, at 05:04, tgerbic < tgerbic@...> wrote: I am not in denial...?? I can quit calibrating equipment any time I want.???????? I just don't want to right now...
...and don't worry about sending me any nice precision resistor, just a plain junkbox 0.001%? resistor with a ¡À0.2ppm/¡ãC tempco would be fine. I can get by with that.
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Re: Precision Voltage Reference
I am not in denial...?? I can quit calibrating equipment any time I want.???????? I just don't want to right now...
...and don't worry about sending me any nice precision resistor, just a plain junkbox 0.001%? resistor with a ¡À0.2ppm/¡ãC tempco would be fine. I can get by with that.
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Re: Precision Voltage Reference
It's not, he's in denial. We should probably get him a nice precision resistor.
Vince - K8ZW.
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On 12/13/22 03:24, Adrian Godwin wrote: > Jeff, some advice from a recovering calibrataholic.
I didn't realise recovering was even possible !
--
Michigan VHF Corporation -- nobucks dot net
K8ZW -
Etsy Shop:
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Re: Precision Voltage Reference
> Jeff, some advice from a recovering calibrataholic.
I didn't realise recovering was even possible !
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Dr. David Kirkby, Kirkby Microwave Ltd