Cheap, not Chinese, Voltage reference for DIY meter calibration - Page 1
Forum section: electronics / testgear

author: dazz1
author_rank: Frequent Contributor
timestamp: June 04, 2024, 10:26:47 am
content: HiI found the thread on cheap Chinese AD584 voltage references but then I started looking at DIY design and build.When I did a search, I found very high performance devices and reasonable prices. Just one example being the Max 6325. 1ppm temp coeff and 0.02% tolerance. Far better than an AD584.https://www.digikey.co.nz/en/products/detail/analog-devices-inc-maxim-integrated/MAX6341CSA/1867167Just wondering if my next project should be to design and build a very cheap and very high performance voltage reference so I can check-cal my small collection of test equipment.

author: tautech
author_rank: Super Contributor
timestamp: June 04, 2024, 10:42:49 am
content: LOL, go for it Dazz !Sorry if our emails had you tossing and turning about this last night.

author: nctnico
author_rank: Super Contributor
timestamp: June 04, 2024, 11:43:51 am
content: Quote from: dazz1 on June 04, 2024, 10:26:47 amThe long term stability and low temperature coefficient are great, but the tolerance is likely higher than you would want for DMM calibrations. A typical 4.5 digit DMM sits around 0.05% already.

author: m k
author_rank: Super Contributor
timestamp: June 04, 2024, 12:23:11 pm
content: Where is tolerance?I found only initial accuracy.

author: BeBuLamar
author_rank: Super Contributor
timestamp: June 04, 2024, 02:20:44 pm
content: I don't understand! Cheap not Chinese?? The AD584 is Analog Device and it may be made in China but the MAX 6341 is by Maxxim Integrated which is part of Analog Device so how would you know that it is not made in China too?

author: Kosmic
author_rank: Super Contributor
timestamp: June 04, 2024, 02:48:47 pm
content: Quote from: BeBuLamar on June 04, 2024, 02:20:44 pmI guess the OP doesn't want people recommending an already made Chinese voltage reference and seem to be incline to go the DIY route?

author: BeBuLamar
author_rank: Super Contributor
timestamp: June 04, 2024, 07:12:30 pm
content: The AD584 is not a premade voltage reference unit. It's just an IC like the MAX6341CSA. So the same amount of DIY work is needed for either option. Now I must admit that it's kind of difficult to determine where the IC is made. The same IC can be made in several different countries. What I know is that Analog Device is an American Company and it owns Maxim Integrated so it's quite possible both chips were made in the same factory.

author: DimitriP
author_rank: Super Contributor
timestamp: June 04, 2024, 08:54:36 pm
content: QuoteIt's main feature is that it can provide 2.5 , 5 , 7,5 , 10 and -10 even using a single IC. Just one!If you are not intrested or don't "need" all of the above with a single IC, there are better choices like the MAX series already mentioned.

author: Martin72
author_rank: Super Contributor
timestamp: June 04, 2024, 09:50:33 pm
content: Quote from: dazz1 on June 04, 2024, 10:26:47 amI will soon have my voltage reference ready so that I can send it off for calibration.Calibration ? Yes, of course, you have to be sure that the reference is actually (significantly) more accurate than the device you want to calibrate with it.Simply building a reference yourself is not enough.

author: dazz1
author_rank: Frequent Contributor
timestamp: June 05, 2024, 05:39:36 am
content: HiOK so by "not Chinese" I meant not from Aliexpress or Bangood. I buy a lot off stuff of Aliexpress so I am not anti.For me, calibration is about confidence, not certification. After reading the thread about actual Chinese voltage reference modules, I wouldn't have confidence in the reference. If I am going to spend $$$ on a reference it should be worth enough to justify a calibration.The Maxim part I quoted was the result of a 2 minute search on a supplier's website. No science behind that choice.One option is to buy the Aliexpress module, and fit a known reference part with providence. I have done that before. I anticipate a "proper" DIY design would get down to the tiny details like solid copper, unplated, connectors to avoid thermo-electric effects and other things.I can't be the only one on the planet that has considered a DIY approach to a voltage reference using off the shelf parts. I am interested to hear the views of others.

author: BeBuLamar
author_rank: Super Contributor
timestamp: June 05, 2024, 10:13:56 am
content: Oh you meant a pre built module that uses the AD584 IC. So you could build yourself a module using the AD584 bought from an electronic dealer in Australia. Here in the USA I would buy it from Mouser, Digi Key or RS-Online.

author: tautech
author_rank: Super Contributor
timestamp: June 05, 2024, 10:16:06 am
content: Quote from: BeBuLamar on June 05, 2024, 10:13:56 amKiwi flag is ours.Not them Aussie rogues.

author: BeBuLamar
author_rank: Super Contributor
timestamp: June 05, 2024, 11:11:53 am
content: Sorry about that. My apology.

author: KungFuJosh
author_rank: Super Contributor
timestamp: June 05, 2024, 01:48:43 pm
content: Quote from: dazz1 on June 05, 2024, 05:39:36 amThat's called false confidence. I am not opposed, but without calibration, you don't know what you're looking at. You can monitor stability from a non-certified reference, and that's useful, but it doesn't tell you about the accuracy of what you're using the reference for.I bought this ref as recommended by another member:https://www.aliexpress.us/item/3256804431053626.htmlI've found it to be very stable, and if I am interested in more than monitoring drift, I'll pay for proper certification.I have a couple other refs I bought from ali, and the worst thing about them was the fake calibration. They were all fairly stable. I think that purple one was the best, but it also got the most use, and that on time leads to stability if it's not a total POS.Quote from: dazz1 on June 05, 2024, 05:39:36 amYou're certainly not. There are many threads dedicated to DIY refs, including this one:https://www.eevblog.com/forum/testgear/elektor-voltage-current-calibrator-project/It's not a cheap project (build cost probably still above $500 per unit), and it should get calibrated too.Whether you go the DIY route, or get a premade ref, they all need significant burn-in time for stability. Once they're stable, they're worthy of calibration.

author: luma
author_rank: Regular Contributor
timestamp: June 05, 2024, 07:58:33 pm
content: How abouthttps://dmmcheckplus.com/Solid reference, but the key value is the cheap and fast calibration service in the future. $20 service + $7 shipping (and free for the first two years) makes a solid reference into a damn useable standard for the home gamer.

author: tautech
author_rank: Super Contributor
timestamp: June 05, 2024, 08:19:09 pm
content: Quote from: luma on June 05, 2024, 07:58:33 pmCertainly one of the best and trusted solutions....and we discussed these at length privately but $ more that Dazz wants to outlay.

author: Martin72
author_rank: Super Contributor
timestamp: June 05, 2024, 08:32:17 pm
content: Quote from: luma on June 05, 2024, 07:58:33 pmI have the device, it's good for a quick check(therefore it´s name) to see if a meter is working.As a reference it is OK for 3.5 digit meters.The LCR option is somewhat sobering.The capacitors and coils are not exact types, but simply measured.But as I said, it's good for testing and comparing.

author: dazz1
author_rank: Frequent Contributor
timestamp: June 26, 2024, 09:45:18 am
content: Quote from: KungFuJosh on June 05, 2024, 01:48:43 pmI have made Elector stuff years ago and it was always nice but it sounds like their quality control is not so good for this project. I see you spent $USD366 on the Elector calibrator.I note there is a commercial calibrator on that thread that was "only" £350https://www.ianjohnston.com/index.php/onlineshop/handheld-precision-digital-voltage-source-2-mini-detailLooks good but too many £££ for my budget.Quote from: KungFuJoshFor that money it would only make sense to get it properly calibrated.Quote from: KungFuJoshLooking at a few data sheets, it appears that the initial value of voltage references can be quite different to the nominal output voltage. Maybe 1% or so. That would make it fairly essential to get it calibrated.

author: dazz1
author_rank: Frequent Contributor
timestamp: June 26, 2024, 10:13:57 am
content: HiI have just found the LB02A process calibrator which looks promising.https://www.aliexpress.com/i/1005001632714207.htmlreviewed here:It is Chinese and not lab quality substitute for a good volt reference but its usefulness could compensate for that.The LB06 is the highest priced version.

author: dazz1
author_rank: Frequent Contributor
timestamp: July 04, 2024, 06:53:48 am
content: HiIt appears the LTZ1000 was replaced by the ADR1000 that was then replaced by the ADR1001.At about $USD100 definitely not the cheapest solution but maybe the best accessible for a DIY solution.https://www.digikey.co.nz/en/product-highlight/a/analog-devices/adr1001-precision-voltage-referenceMarco Reps channel did a ADR1000 reference

author: BennoG
author_rank: Frequent Contributor
timestamp: July 04, 2024, 08:31:12 pm
content: what about this one.https://voltagestandard.com/I have looked at it but not yet ready to buy one.Benno

author: Kosmic
author_rank: Super Contributor
timestamp: July 04, 2024, 11:11:17 pm
content: Quote from: dazz1 on July 04, 2024, 06:53:48 amPlease note that the LTZ1000 is still produced and available (so not replaced by the ADR1000).ADR1000 is the newer version and one of the improvement is lower noise. Still not readeally available though (last time I checked).ADR1001 is the SMD variant (so do not replace the ADR1000).

author: dazz1
author_rank: Frequent Contributor
timestamp: July 05, 2024, 02:52:41 am
content: Quote from: BennoG on July 04, 2024, 08:31:12 pmThey look nice but they are in imperial units because these are made in the US of A. I don't know anyone who has a thermometer to measure 68°F.When I go to checkout, none of the addressable states are outside of the USA.Previous experience tells me that shipping anything across the US border is excessively expensive, especially if a courier service is used.It is cheaper to buy a metric voltage standard.So yes, but no.

author: dazz1
author_rank: Frequent Contributor
timestamp: July 05, 2024, 03:39:34 am
content: Quote from: Kosmic on July 04, 2024, 11:11:17 pmThat's what happens when I skim across the Internet.I could not find a supplier of the ADR1000 but Arrow and Digikey sell the ADR1001EBZ device and ADR1001AEZ eval board.Not the cheapest device but I'd say good value for the $$. Spend more and get more.

author: schmitt trigger
author_rank: Super Contributor
timestamp: July 05, 2024, 05:26:49 pm
content: Quote from: dazz1 on July 05, 2024, 02:52:41 amThere is a pull down menu with a list of the World’s countries. New Zeland is there. Mexico is also there and if selected the Mexican state menu will appear.With respect to the 68F label, it means the unit was calibrated at that temperature, meaning 20C.

author: dazz1
author_rank: Frequent Contributor
timestamp: July 06, 2024, 01:49:39 am
content: Quote from: schmitt trigger on July 05, 2024, 05:26:49 pmPlease excuse my poor attempt at sarcasm.

author: jrharley
author_rank: Regular Contributor
timestamp: July 06, 2024, 04:57:05 pm
content: For what it's worth, I have found the LB02A to be fantastic!Wouldn't call it a true standard, but it's incredibly capable and easy to use. - JRH

author: dazz1
author_rank: Frequent Contributor
timestamp: July 06, 2024, 11:51:00 pm
content: Quote from: jrharley on July 06, 2024, 04:57:05 pmI am looking at this as the complimentary opposite to a bench top multi-meter. Where a multi-meter measures A,V, Ohms and sometime other things, the LB02A generates these. I could see this being useful for prototype development.At a pinch, it could be used as a basic transfer standard, but not in a certified calibrated way.I don't see the LB02A as a voltage standard like I don't see a voltage standard being a process calibrator.

author: tonyalbus
author_rank: Super Contributor
timestamp: September 07, 2024, 07:51:41 pm
content: Here the LB02A , SG003A, SG004A and DMMcheckplus rev.6 and rev.8 side by side.

author: KungFuJosh
author_rank: Super Contributor
timestamp: September 07, 2024, 08:14:05 pm
content: I recently got Doug'sVREF10-001 r9and it's 10V which is more standard for a voltage ref, and it's higher accuracy than the DMMCheckPlus. I'd only get the latter if you need the LCR references v8 includes.

author: BennoG
author_rank: Frequent Contributor
timestamp: September 08, 2024, 06:53:10 am
content: Quote from: KungFuJosh on September 07, 2024, 08:14:05 pmYes I am looking at this for a while now planning on buying one sometime (to add to myaddictioncollection)I have a 7 1/2 dmm and a couple of 6 1/2 dmm. I would like to use it as some transfer calibration tool, an calibration check tool.Benno

author: skander36
author_rank: Frequent Contributor
timestamp: September 08, 2024, 11:13:16 am
content: Quote from: BennoG on September 08, 2024, 06:53:10 amA reference with LT1021 with 5 ppm drift should never be used in calibration process of a 7,5 digit DMM or even in 6,5 digit. Their internal references are at least ten times stable that LT 1021 so you may alter calibration process. Use at least LM 399, or LTZ1000 or newer references.

author: J-R
author_rank: Super Contributor
timestamp: September 08, 2024, 09:09:30 pm
content: Doug's VREF10-001 r9 has a few changes to make it better. The price also includes 2 years of free calibrations. However, if you have the money, there is the PDVS2mini:https://www.wrytech.eu/products/pdvs2

author: KungFuJosh
author_rank: Super Contributor
timestamp: September 08, 2024, 10:06:38 pm
content: I agree it probably shouldn't be used to calibrate those meters, but it's still a great reference for them. The stability I found with my 6.5 digit meter was excellent.I wanted the PDVS2mini for a while, but spending more than double the cost of the VREF10-001 r9 wasn't cool with my wallet. If I'm going to invest that much for a ref, I'd rather build the Elektor project Martin72 was doing. I'm still tempted, maybe someday.

author: dazz1
author_rank: Frequent Contributor
timestamp: September 09, 2024, 12:54:43 am
content: Quote from: KungFuJosh on September 08, 2024, 10:06:38 pmI have a fond spot for Elektor because back in the day, I considered them to be a source of advanced or professional quality circuits. Although this Elektor Voltage Reference projecthttps://www.elektormagazine.fr/labs/voltage-current-calibrator-0-to-10v-and-0-to-40ma-0001appears to be community contributed, it looks like an Elektor project. I haven't priced the BOM (Elektor projects were never cheap) I suspect it would be good value for the money. It looks fairly straight forward to build.Has anyone built one of these?

author: KungFuJosh
author_rank: Super Contributor
timestamp: September 09, 2024, 01:09:04 am
content: Quote from: dazz1 on September 09, 2024, 12:54:43 amMartin72 has:https://www.eevblog.com/forum/testgear/elektor-voltage-current-calibrator-project/I modified the PCB design a bit, and was planning on building one, but the cost is high. The LCD and some of the chips are expensive. If not for cost, and then wanting to have it calibrated (and significantly increase the investment), I would have made one too.

author: dazz1
author_rank: Frequent Contributor
timestamp: September 09, 2024, 01:33:13 am
content: I found the YT videowhere the author/designer indicates a build price of around €300. Ouch, ouch, ouch.For that price I can buy a used precision bench multi-meter plus a Chinese process calibrator. That combination would be far more useful and versatile.

author: KungFuJosh
author_rank: Super Contributor
timestamp: September 09, 2024, 01:45:35 am
content: Quote from: dazz1 on September 09, 2024, 01:33:13 amYeah, that's old. That's before covid made the world more expensive. It's more like 500 now. 300 will literally get 2 of the chips and the LCD now.

author: dazz1
author_rank: Frequent Contributor
timestamp: September 09, 2024, 02:02:36 am
content: Quote from: KungFuJosh on September 09, 2024, 01:45:35 amAt that price the Elector unit is a non-starter for me. It would be nice to build the Elector unit, but value for money is not there for my use-case.

author: KungFuJosh
author_rank: Super Contributor
timestamp: September 09, 2024, 02:20:31 am
content: Quote from: dazz1 on September 09, 2024, 02:02:36 amSame for me. Even the VREF10-001 r9 I bought is well beyond my needs...and more than I should have spent, but you know. TEAS.

author: GigaJoe
author_rank: Frequent Contributor
timestamp: September 15, 2024, 02:47:15 am
content: since 587 not available in overallAD588 + thermal correctionhttps://www.ebay.com/itm/323780690966?

author: dazz1
author_rank: Frequent Contributor
timestamp: September 15, 2024, 08:42:26 pm
content: HiI updated the BOM for the Elector Voltage Reference here:https://www.eevblog.com/forum/testgear/elektor-voltage-current-calibrator-project/msg5643277/#msg5643277It looked like a viable option until I priced the DAC and LCD.This leads me to conclude that the most cost effective and versatile option would be an old bench multimeter (7 1/2 or 8 1/2 digit) with an aged and stable voltage reference, combined with a reasonably priced process calibrator.That combination would provide the same capability, with greater functionality, than the Elektor device. That doesn't mean I wouldn't like to build the Elektor reference.

author: tggzzz
author_rank: Super Contributor
timestamp: September 15, 2024, 09:11:35 pm
content: Too complexWhy not reuse the concepts in old differential voltmeters? That avoids the need for calibrated high resolution voltmeters; all you need is something that reads 0V accurately (e.g. the crappy 20kohm/V 2% moving coil meter at the back of your storecupboard!)A high voltage is divided down by a Kelvin-Varley divider. The divided voltage is compared with the known reference voltage, and the KVD ratio twiddled until they are the same. From that you can calculate the high voltage.You can get 7-decade KVDs on fleabay, capable of having 1kV as the high voltage.If you look at the Fluke 893 manual, you will see that's what is inside.That's the mechanism we used at school to measure voltage to 0.1% using a 2% meter and 1m of wire. We could have measured to 0.01%, but that would have required a 10M piece of wire.

author: dazz1
author_rank: Frequent Contributor
timestamp: September 15, 2024, 11:22:32 pm
content: Quote from: tggzzz on September 15, 2024, 09:11:35 pmToo simpleYou obviously don't understand the concept of over-engineering.Although I did help my daughter with a school science project. She was able to measure the weight of air compressed in a balloon with a stick, string and paper clips. That was waaaay too simple, but remarkably accurate.My main problem is that the Elektor Voltage reference is the solution to a problem I don't have.

author: tggzzz
author_rank: Super Contributor
timestamp: September 15, 2024, 11:40:18 pm
content: Quote from: dazz1 on September 15, 2024, 11:22:32 pmPlaying like that with your daughter is funNow ask her to calculate the weight of a fully developed cumulo nimbus cloud. Zero it ain't(Since you are in NZ, start your daughter flying gliders before she can start to drive a car. My daughter had great fun learning a lot of things that way.)And apparently youdohave a problem, whether or not the Elektor reference would solve itWelcome to the rathole

author: dazz1
author_rank: Frequent Contributor
timestamp: September 16, 2024, 12:18:16 am
content: Quote from: tggzzz on September 15, 2024, 11:40:18 pmMy daughter is now old enough to be married and own her own house. She is still my little girl.I remain in a constant state of internal conflict. The rational part says: don't need it, don't buy it. The irrational part says: I want it, therefore I need it. When will it end?

author: KungFuJosh
author_rank: Super Contributor
timestamp: September 16, 2024, 12:38:25 am
content: Quote from: dazz1 on September 16, 2024, 12:18:16 amThere is no end. The TEAS thread has 136,715 replies and counting. But hey, at least you're not alone. 😉

author: tggzzz
author_rank: Super Contributor
timestamp: September 16, 2024, 08:22:45 am
content: Quote from: dazz1 on September 16, 2024, 12:18:16 amSnap!QuoteThe internal conflict has two endpoints. One is too soon and too permanent. The other is when you say "I'm worth it, and I've earned it". Time fpr you to join the TEA thread.The next form of angst is that your daughter may choose to wind you up by saying "when I have to clear out the house, it's all going straight to the tip". You can (attempt to) counter that by startling her by showing what people pay on fleabay for that boring little box/wire/etc.She will then take delight in sending you this...