DMMCheck Plus Multimeter Reference(and other References) - Experiences.. - Page 1
Forum section: electronics / testgear

author: Martin72
author_rank: Super Contributor
timestamp: July 02, 2023, 10:45:12 pm
content: Hi,Welectron offer this board together with the L/C option, it sounds very promising...AC/DC current, AC/DC voltage, resistance, capacity, inductance - everything together in one box.Quotehttps://www.welectron.com/DMMCheck-Plus-Multimeter-Calibration-Reference-with-L-C-OptionBefore I hit the buy button, what are your thoughts ?Thanks in advance..

author: sokoloff
author_rank: Super Contributor
timestamp: July 02, 2023, 10:59:01 pm
content: I bought one and am happy with it. I don’t have the L/C option, but the others all indicate that my meters aren’t crazy off. I don’t know how I’d be “sure” how calibrated it is, but based on the paperwork I got with it, I’m inclined to believe it is as-specified and as-measured.

author: Martin72
author_rank: Super Contributor
timestamp: July 02, 2023, 11:27:23 pm
content: QuoteI would trust that in this case, based on the technical data of the components used.Welectron offers an additional calibration, once according to ISO standard or even DakkS (globally accepted standard) standard.Would be another 85 or 115 € in addition, does not necessarily have to be...For now.

author: KungFuJosh
author_rank: Super Contributor
timestamp: July 03, 2023, 12:48:56 am
content: Have you looked at purchasing it directly? Assuming the shipping isn't crazy, it should cost a lot less.https://dmmcheckplus.com/shop/ols/products/dmmcheck-plus-without-enclosure

author: J-R
author_rank: Super Contributor
timestamp: July 03, 2023, 01:35:22 am
content: I've had the main board for about 5 years and the L/C board for about 2 years. If you don't have any references/standards already, it can be a great way to kick start things and get a bunch all at once. However, it needs to be shipped off for a yearly calibration to be of much use, IMHO. It is going to drift a little over time, and my calibration data reflects that. But also I think that is the main advantage of it. It's very small and can be shipped around for very little money (relatively speaking).The main shortcoming is the limited output values. So what are you planning to do with this?

author: bdunham7
author_rank: Super Contributor
timestamp: July 03, 2023, 01:46:44 am
content: Quote from: J-R on July 03, 2023, 01:35:22 amHow much drift do you see? I can't imagine using these for anything beyond the 4.5-digit level--am I wrong?

author: tautech
author_rank: Super Contributor
timestamp: July 03, 2023, 02:28:29 am
content: Quote from: bdunham7 on July 03, 2023, 01:46:44 amDoug has been making these for a good while now and keeps his 8.5 digit Calibration DMM in Cal.I suspect you can calibrate a 6.5 digit meter with confidence with these.He also offers a cheap recalibration service:https://dmmcheckplus.com/technical-information

author: bdunham7
author_rank: Super Contributor
timestamp: July 03, 2023, 02:55:22 am
content: Quote from: tautech on July 03, 2023, 02:28:29 amDMMCheck is not the same as voltagestandard.com, although apparently they used to be the same. Doug's 10V reference is 24ppm and indeed is good enough for a reference to check a 6.5-digit DMM, but the DMM-Check product is nowhere near that accurate AFAIK.

author: tautech
author_rank: Super Contributor
timestamp: July 03, 2023, 02:58:51 am
content: FWIW we supplied a tech EDU with 15 units 15B Fluke DMM's and HOD got a DMMCheck Plus to monitor their aging which after 1 year two units were 1 LSD from the other 13 but all still within spec.However, students being what students are, all DMM's need measure exactly the same so those 2 units were adjusted as you can with a 15B so they all showed the exact same values = no classroom arguments !

author: J-R
author_rank: Super Contributor
timestamp: July 03, 2023, 04:18:21 am
content: I purchased my DMMCheck Plus from Doug, but as stated he sold that one specific product to Russ a while ago. I've had no issues with either individuals.After about 15 months from purchase, the 5VDC reference had drifted up to approximately 5.000,37V. Two years after that I don't have the as-received, unfortunately. One year after that (now) and it is 4.999,95V. I'm adding one extra digit because I can, but the calibration printout will only have 5.000,0V for example.As for the standards, it depends, and actually I've had three add-on boards overall. First was just the capacitance standards, then the first L/C board (VERY low serial number) which was replaced at the next calibration for reasons I can't recall, maybe a component was damaged.The resistors are about 5 years old at this point and the drift is minimal. I'd say the 5th digit on your 4.5 digit DMM will be within 1-2 counts, generally speaking.The free calibration for the first two years may only apply to US customers. But again, a primary aspect of this unit is being able to easily ship it for regular calibrations.

author: Domitronic
author_rank: Regular Contributor
timestamp: July 03, 2023, 07:34:30 am
content: Quote from: Martin72 on July 02, 2023, 10:45:12 pmI think it is nice but i don't see the use case for me. If you have multiple DMMs you can compare them to see if they are drifting. If you only have one then you could buy another one for that price or send the one for calibration.I could not justify to buy the DMMCheckPlus for two reasons. One is that i don't do anything at home where high accuracy is required. The other one is that i could check my multimeters by comparing them to a calibrated 6.5 digit DMM at work.

author: Fungus
author_rank: Super Contributor
timestamp: July 03, 2023, 08:08:34 am
content: Quote from: Martin72 on July 02, 2023, 10:45:12 pmHave you seen these?https://www.aliexpress.com/item/1005002190676191.htmlhttps://www.aliexpress.com/item/1005004219629979.htmlhttps://www.aliexpress.com/item/1005004221641169.html(random examples)https://www.eevblog.com/forum/testgear/cheap-chinese-ad584-voltage-reference-legit-cal-data-let_s-find-out!/

author: J-R
author_rank: Super Contributor
timestamp: July 03, 2023, 10:12:50 am
content: With a freshly calibrated DMMCheck Plus, you could put a 6.5 digit DMM through (some of) its paces. You get a full page of trust-worthy numbers to compare against.Can you use it to calibrate/adjust any of your test equipment? Well, generally not really, although there are perhaps rare exceptions. Specifically, I used it to adjust the 5V range on my BM869s, which really made the 500,000 count DCV mode significantly more useful. I also do recall using the four resistors to calibrate a Fluke 8842A.And maybe a less-common tactic is to leverage known-good values along with Ohm's law in various ways to expand the range of usefulness of the references.

author: KungFuJosh
author_rank: Super Contributor
timestamp: July 03, 2023, 03:25:54 pm
content: Quote from: Fungus on July 03, 2023, 08:08:34 amThose random examples are all trash. I bought them (thankfully they're inexpensive trash 😉). Most of them don't come with any reference values written. NONE of them come with any form of certification for the values written. The one unit I received that had values written, was mostly bs. I think 3 out of all the written numbers were accurate (checked across multiple meters with higher digit counts than the reference numbers).The only value for any devices like these are if you know they're measured/calibrated from a reliable source.

author: Martin72
author_rank: Super Contributor
timestamp: July 03, 2023, 06:24:12 pm
content: Hi,Thank you so far for all the hints and advices.What I like on this board is to have not only voltage references, but also having current references - I would check my tek probe with them (plus several windings through the probe).And having LCR references.The combination of R-C-L references, voltage, current and frequency references I only found with this board.Further comments are welcome..

author: rhb
author_rank: Super Contributor
timestamp: July 03, 2023, 06:47:01 pm
content: I've had the DMMCheckPlus and the 10 V reference for several years. Quite happy with them, though they need a recal. I did by mine directly from Doug.I'll adjust it when I get the USA Cal Kit round 3 package. I know of no turnkey option that is as good without being 10-100x the price. If something happened to mine I'd buy another unless I'd picked up a Fluke or HPAK voltage rcalibrator.I do notice the price has roughly doubled IIRC.BTW At the level of your "drift" you need to record the temperature and measure the tempco. fpr buget precision voltage references used LM399s are the best deal if you want to build a bespoke calibrator or reference.https://www.ebay.com/itm/121069770252They have much lower aging rates from many years of use.Have Fun!Reg

author: KungFuJosh
author_rank: Super Contributor
timestamp: July 03, 2023, 06:50:09 pm
content: You might want to wait or email before buying them. I think I saw an ad on their header banner about a new high precision device coming soon.

author: tomud
author_rank: Regular Contributor
timestamp: July 03, 2023, 07:13:04 pm
content: Quote from: J-R on July 03, 2023, 10:12:50 amIMHO not very useful equipment ... Unfortunately, one voltage and only one current source is not enough to test the DMM in any meaningful way. In fact, it will work only on one measuring range (which does not tell us much about the multimeter because the tested measurement range may be ok, and the problem may occur on other ranges)Unfortunately, the equipment is poorly thought out, even if we are talking about a simple DMM test, not to mention calibration... To tell the truth, I would rather spend these over 200 euros, for example, on the purchase of ultra high precision z-foil resistors etc.

author: tatel
author_rank: Frequent Contributor
timestamp: July 03, 2023, 07:52:04 pm
content: Quote from: KungFuJosh on July 03, 2023, 12:48:56 amIf you are on Europe, the full-blown version with LC, dual frequency, enclosure, etc, sets you back €239 on welectron, shipped, and you can have it ISO calibrated for €85 (plus shipping, I guess).On the page you provided, a similarly equiped deviced would be $197.50 plus shipping. Shipping from the US to Europe is often ridiculously expensive so I bet it's cheaper to purchase it in Welectron. Not to mention that you would also have to pay VAT for item's price + shipping. Not to mention the piratic fees Western couriers charge for customs paperwork. Probably €50 more for an import in that price range. If you send it back to the US for calibration, you'll have to deal again with customs... probably twice. So, to purchase it in the US? Thanks but no, thanks.Certainly it's not cheap, but since I didn't have any referencies, and those doesn't seem to be cheap either, it seemed a reasonable deal to me. So I got one to check all my multimeters. To me, main advantage is the availability of a calibration service in Europe. Should my multimeters disagree, I will not need to wonder which one(s) drifted, but I will know it for sure. Or so I hope.However, I'm not planning to have it calibrated yearly. I'm planning to do it only if I'm seeing my meters disagree unreasonably. Now I have HP 3456A, Brymen 869s, DER DE-5000 (from Eleshop, not gray market -ouch!), UT61E and UT210E. While Uni-T meters are cheaper than DMMCheck calibration, I don't think replacing the better ones if they disagree is a very sensible option.I think it would be also useful to get one of these multiple voltage references from some guy in the UK... but then we are again dealing with customs and Western courier/pirates, so... no. I would need to be able to have it purchased and calibrated within European Union before pulling that triggerI wonder how I could get those referencies and get them calibrated without becoming a volts-nut and expending even more money in the long run. After having some looks at the Metrology section, I really got scared. So, to me, it's purchasing DMMCheck and perhaps some similar, voltage-related COTS product and to have it calibrated if and when deemed strictly necessary. For my needs and skills, that's probably already overkill.

author: KungFuJosh
author_rank: Super Contributor
timestamp: July 03, 2023, 08:20:11 pm
content: Quote from: tatel on July 03, 2023, 07:52:04 pmThat's why I avoid that area. 😉

author: Martin72
author_rank: Super Contributor
timestamp: July 03, 2023, 09:12:51 pm
content: Quote from: tatel on July 03, 2023, 07:52:04 pmThis is the point.Importing the item from the states will cost nearly the same when buying it here from welectron.Plus the US website explicitly tells you to buy from welectron if you are based in Europe.I had used welectron's calibration service on my Brymen 869s and did not regret it.Our calibration service that we use from work only states.If something is out of tolerance, it is sent back blocked.The service from Welectron determines AND readjusts it...Very good.QuoteI feel the same way.The reference may not meet higher demands, but if my multimeters already show "strange" values on it, then that is enough to become active.Currently, I am very strongly inclined to buy the device.

author: rsjsouza
author_rank: Super Contributor
timestamp: July 03, 2023, 09:50:51 pm
content: I have one of these purchased in 2019 from Doug (non-LC version). Excellent for a quick sanity check of the various meters I have - something that seems to agree with your expected usage as well.

author: J-R
author_rank: Super Contributor
timestamp: July 03, 2023, 11:24:07 pm
content: Yes, absolutely the DMMCheck Plus is limited at face value, but it's trivial to transfer the confidence around your bench to other devices and also generate further permutations with Ohm's law as I mentioned (solve for the unknown).I don't think that gets enough attention, and it's one of the tricks so to speak that I personally use to check things from multiple angles.Example: I could verify some of my DMMs using the 1mA and 5V references, then connect those DMMs up to a DC supply and go to town on checking resistors. I'd feel really confident from about 100-5K Ohms in this setup. How many digits you consider valid will depend on your equipment and you do want to calculate some worse-case values to get an idea of what is sensible. As I proved in another thread, even the junkiest of equipment ($50 PSU and $30 DMM) can be used to verify low-value resistors at 3 digits using the Kelvin method.Contemplating this more, I do think the calibrated passives are probably the best bang for the buck feature on the DMMCheck Plus.For primarily voltage and current it's probably more sensible to just have a couple decent DMMs sent out for calibration and then use them along with a bench supply to generate what you need. I've found most bench supplies are more stable in voltage regulation than current regulation, so I use that even when generating a precise current. You monitor the current using the DMM...

author: Electro Fan
author_rank: Super Contributor
timestamp: July 04, 2023, 01:13:31 am
content: The comments above regarding how accurate they are and continue to be are pretty consistent with my experience.I bought 3 of their products way back in the day and was/have been happy with all of them (two are marked 2011-12 Rev 1, and one is 2008 R4).Since then there have been various improvements.Overall, it's mostly a function of your TEA to budget ratio, so YMMV.Having said all that, Doug is a good guy making good products, so I'd say if in doubt but you can afford it, go for it.

author: Fungus
author_rank: Super Contributor
timestamp: July 04, 2023, 06:13:00 am
content: Quote from: KungFuJosh on July 03, 2023, 03:25:54 pmI've measured mine on various multimeters and it seems legit.There were quite a few in that thread I linked to that were legit, too.Quote from: Electro Fan on July 04, 2023, 01:13:31 amThe hardware in those devices seems OK, it's the calibration where some sellers are cutting corners.I'm sure you can get a good one if you take the time to go through all the Aliexpress comments/ratings. I just posted a few random listing to give an idea of prices.nb. The references in them are probably pulled from old devices. The silver lining is that they'll be well burned-in.

author: Fungus
author_rank: Super Contributor
timestamp: July 04, 2023, 06:16:28 am
content: Quote from: Electro Fan on July 04, 2023, 01:13:31 amYep. Doug will obviously give you a garantee, etc.

author: iMo
author_rank: Super Contributor
timestamp: July 04, 2023, 07:40:33 am
content: First step when buying such a reference box is to look at its schematics. While doing so you'll get what the parameters really are. Most notably the reference chip and the resistors around the reference are the key.

author: KungFuJosh
author_rank: Super Contributor
timestamp: July 04, 2023, 03:05:48 pm
content: Quote from: Fungus on July 04, 2023, 06:13:00 am100% - and that's the most important part. None of them are that expensive, but buy the time you buy them all to find one that's accurately calibrated and labeled, you might as well buy something nicer. I did read reviews, but people are often clueless, or fake.

author: Fungus
author_rank: Super Contributor
timestamp: July 04, 2023, 06:09:54 pm
content: Quote from: KungFuJosh on July 04, 2023, 03:05:48 pmSeems like a business opportunity for somebody with a decent DMM. Buy them cheap, calibrate them, sell them a bit more expensive.

author: Martin72
author_rank: Super Contributor
timestamp: July 04, 2023, 06:25:18 pm
content: Calibration is a kind of "official" confirmation that a meter is in it´s own specs.If you have a cheap meter with lousy specs calibrated, you have official confirmation that the meter is lousy.Great...

author: Martin72
author_rank: Super Contributor
timestamp: July 04, 2023, 06:49:45 pm
content: So now it's on, I just ordered the DMM reference with L/C option....Should arrive this week.Voltage, current, frequency, resistance, inductance, capacitance. ,optics, what is in papers with it..... I will then test and report here of course.

author: Fungus
author_rank: Super Contributor
timestamp: July 04, 2023, 06:51:04 pm
content: Quote from: Martin72 on July 04, 2023, 06:25:18 pmWhat if you have a cheap meter with really good specs?eg.https://lygte-info.dk/review/DMMAnengAN870%20UK.html

author: Electro Fan
author_rank: Super Contributor
timestamp: July 04, 2023, 07:04:53 pm
content: Quote from: Fungus on July 04, 2023, 06:13:00 amJust to clarify/confirm....When I said:The comments above regarding how accurate they are and continue to be are pretty consistent with my experience.I bought 3 of their products way back in the day and was/have been happy with all of them (two are marked 2011-12 Rev 1, and one is 2008 R4).These ^ are all references to the voltagestandard.com and DMMCheck Plus products. 5V Reference was 2008, PentaRef was 2011, and DMMCheck Plus was 2012.

author: rhb
author_rank: Super Contributor
timestamp: July 04, 2023, 07:57:53 pm
content: Quote from: Fungus on July 04, 2023, 06:51:04 pmI tested 8-9 "Free with any purchase" Harbor Freight DMMs which sell for $5-6 now. They were all in spec and I adjusted them all to <0.1% ( the limit of resolution for a 3.5 digit meter). Unless I'm at my bench with dual 3478As and 34401As, I'm most likely to use one of those. I'm probably down to 3 or 4 now. I got them to give away. Dad and I bought slew of them for $2 on sale before they started giving them away.I have them in many places and toolboxes. If needed I have 4.5 digit Tenma bench DMM with an internal battery pack for portable use. But having a DMM in the dry cell drawer is very handy.I feel very confident that anyone buying one of Doug's products will be very pleased.Have Fun!Reg

author: jchw4
author_rank: Regular Contributor
timestamp: July 05, 2023, 08:28:40 am
content: Quote from: Martin72 on July 04, 2023, 06:49:45 pmCould you share your calibration certificate that you receive with it?I got mine long ago from voltagestandard.com and could not be happier. But after the project was sold to the new owner and since then my experience was not as good as with Doug. I added the LC option and I don't feel strong about it.

author: Martin72
author_rank: Super Contributor
timestamp: July 05, 2023, 09:30:19 am
content: Will do when it's here.

author: J-R
author_rank: Super Contributor
timestamp: July 05, 2023, 10:33:02 am
content: What is your concern with the L/C board? One thing to note is that the values are taken at 10kHz. Early printouts did not state that.Here is a calibration sample from their website:https://img1.wsimg.com/isteam/ip/c544540f-524c-4b38-8d0c-cbfda88bf37a/blob.pngMy printout from 2022 looks the same.

author: tomud
author_rank: Regular Contributor
timestamp: July 05, 2023, 09:15:18 pm
content: Quote from: Fungus on July 04, 2023, 06:51:04 pmCurrently, most even cheap multimeters have very good accuracy, be it Aneng or UNI-T... However, when it comes to the meaning of the term "multimeter calibration", we must first establish what we mean by it. Unfortunately, in many countries certain procedures have different names and some confusion can arise here.Heh... I could even mention UNI-T multimeters, which when new are sometimes better than BM869 or other multimeters of this class (if we talk about accuracy)For example, a relatively cheap multimeter calibration can be performed and can either consist of programming the calibration data into the device so that the multimeter reads correctly. We can also receive a printout on which the multimeter is compared with the reference equipment - then using, for example, the table we have, we can manually calculate and correct the indications. We can, for example, do something like this for private use. This is only a calibration and we do not get a certificateThere are also cases, most often in companies where we need a certificate (this is defined by the relevant standards ISO etc.) from an accredited laboratory - such a document has a certain legal force and most often such a procedure is more expensive than the so-called. "calibration".Going back to those cheap multimeters, the device is accurate, and even if we pay and get a certificate for the device (which must be renewed periodically), there is still the question of how much we can trust the multimeter in the intervals between certifications. Unfortunately, the accuracy of multimeters is not everything and as I mentioned when the equipment is new, even the cheapest ones are in most cases very good.The problem is, unfortunately, that here we can never be sure how long the multimeter will keep these good parameters, unfortunately in the case of cheap multimeters it does not look so good. In such cases, it is worth having not so much as some reference sources, but a better quality multimeter with which we can periodically check such cheaper equipment whether something is broken and does not show measurements very distant from reality.This is an example from my experience. For example, one of the multimeters I use more often is the Brymen BM869S - bought over 5 years ago. The equipment is heavily exploited, it has had several falls to the ground from a greater height. I don't treat him like an egg either. In fact, although the housing does not look so nice anymore, the multimeter still maintains the declared parameters, and the multimeter did not require calibration (saving calibration data in the eeprom memory).Unfortunately, it is not so beautiful with cheaper multimeters, e.g. wear of a rotary switch or poor quality sockets (cheap metal plates) is already starting to affect the measurements, and their accuracy has deteriorated significantly. Currently, they are more suitable as an "indicator" to check whether there is voltage or notHere in all this the most important thing is the awareness of all this, not whether we have this type of "calibrator" or even a certificate.Personally, I prefer to use 6 1/2 digital meters to test the cheaper millimeters - this is where I feel more confident about the procedure. Why ? It's unlikely that all three of my lab multimeters will suddenly fail or lose their performance. So even if one breaks, I'll be able to spot it very quickly.Their accuracy is just as more than enough to be used as standards for cheap multimeters, I don't need an 8 1/2 multimeter to test multimeters 4 1/2 digits and below.In fact, this is a more reliable method of evaluating multimeters than certifying a cheap multimeter or having a single reference voltage source (which can also fail).Of course I have some Chinese reference voltage source. However, it is not used as a reference source, but only as a time-stable voltage source - which is also sometimes useful in testing. Knowing the exact voltage of this source is not the most important thing here.

author: rsjsouza
author_rank: Super Contributor
timestamp: July 06, 2023, 11:03:10 am
content: My experience reflects tomud's as well; the various cheaper multimeters are indeed quite accurate but only until the point of wearing their mechanical components (jacks and mainly rotary switch). Surprisingly my old UT61E has been holding itself quite well, but it hasn't suffered any major falls (for the hard work I have an old brown Fluke 27/FM).As I learned a long time ago: it is easy to make a product that works; it is much harder to make a product that works AND has endurance.

author: Svgeesus
author_rank: Regular Contributor
timestamp: July 06, 2023, 05:04:30 pm
content: Quote from: bdunham7 on July 03, 2023, 01:46:44 amI bought a DMMCheckPlus 10 years ago, and a couple of years ago I sent it back for recalibration. Both the original cal and the recal were done with an in-cal 8.5 digit meter, and the drift was substantially less than one would expect based on the Vref datasheet.My meter is 6.5 digit and out of cal for 5 years so I can't compare my readings to his with any confidence. But I am happy to trust his cal certificate.I also find that having DC V, AC V, current, frequency and resistance all on the one unit to be great as a sanity check before any sort of reading on my main meter.

author: Fungus
author_rank: Super Contributor
timestamp: July 06, 2023, 05:09:12 pm
content: Quote from: tomud on July 05, 2023, 09:15:18 pmAround here that would be called "adjustment"."Calibration" - measuring reference values and producing a report."Adjustment" - modifying the device to improve the accuracy of the displayed values.Quote from: rsjsouza on July 06, 2023, 11:03:10 amI've only had one meter go bad (via the rotary switch) and it wasobviouslybad, ie. It didn't display sensible values.If you're going to be dropping it from ladders on a regular basis then it obviously makes sense to buy a decent meter and the cost probably won't matter - you're being paid to be up that ladder.If you're working with dangerous voltages then "trust the meter" isn't enough. You should own a proving unit (and use it).https://www.fluke.com/en/product/electrical-testing/basic-testers/prv240-proving-unitI assume all the meter nannies around here do that, right?If you're not throwing it off rooftops and/or working in arc flash environments then how much is this is relevant? A meter that doesn't work will be found out in minutes. Just bin it and grab one of the others.(and as noted, this isveryinfrequent in my own anecdotes)

author: Svgeesus
author_rank: Regular Contributor
timestamp: July 06, 2023, 05:15:20 pm
content: Oh and also to mention excellent customer service.Quote

author: Veteran68
author_rank: Frequent Contributor
timestamp: July 07, 2023, 12:32:57 am
content: Quote from: KungFuJosh on July 03, 2023, 03:25:54 pmI have a few different varieties of these for both voltage and LCR references, including the one that takes the weird 10F2015 15V battery, and they all came with written values which checked out according to my Agilent 34401A. Most if not all came from Amazon but don't know that that makes them any more "legitimate" than an AliExpress seller.

author: KungFuJosh
author_rank: Super Contributor
timestamp: July 07, 2023, 12:38:31 am
content: Quote from: Veteran68 on July 07, 2023, 12:32:57 amI think it's a roll of the device depending on who you get them from. I tried a voltage ref from Amazon, and it was pretty darn close to the marked value (like within .0001)...but also died the second time I tried turning it on.

author: all_repair
author_rank: Frequent Contributor
timestamp: July 07, 2023, 03:15:25 am
content: Quote from: Veteran68 on July 07, 2023, 12:32:57 amAll of mine were as good as they were specified. These are not something that low-ball sellers are interested. Firstly volume is not high, and secondly buyers are of a higher level that the sub-standard goods can get away easily.

author: tomud
author_rank: Regular Contributor
timestamp: July 07, 2023, 06:59:02 am
content: Quote from: Fungus on July 06, 2023, 05:09:12 pmIt's not like we call something a given procedure in our own way. It's about what nomenclature is used officially in different countries because unfortunately I don't know.For example, in Poland there are two words that translate to the same word calibration in English ("wzorcowanie", "kalibracja")The concept of calibration ("kalibracja"), for example in Poland, means setting the multimeter, if possible, that is, saving new correction data to the device, and if the equipment does not have such a possibility, providing a comparison table with the reference device. This is usually a much cheaper service that I personally use on hobby equipment. For example, the cost of such a service at the authorized distributor of Brymen in Poland (Biall company - have their own accredited laboratory) - i.e. calibration consisting in saving calibration data to the eeprom memory of the multimeter is about 45 euros + VAT.There is also such a service performed in accordance with the ISO 17025 (PN-EN ISO/IEC 17025) standard, it costs more. This is called calibration ("wzorcowaniem" - written in Polish) by issuing a "certyfikat wzorcowania" (written in Polish). Translating into English and German (but I don't know if it's a correct translation): "calibration certificate", "Kalibrierschein"... Such calibrations must, for example, be performed by ISO-certified companies.Therefore, when writing about calibration here, there may be some misunderstandings due to language differences. So if we are talking about some documents issued by accredited laboratories, it is worth mentioning whether they are in accordance with ISO 17025 or is it just a simpler service of setting / comparing the multimeter with the reference.-------Coming back to cheap measuring equipment. It's ok, you can buy one (I recently bought such inventions as Aneng A3008 and A3009 - but I will use them more as an indicator of whether there is voltage). However, keep in mind that this accuracy may change over time. Similarly, in the case of such multimeters, quality control is practically non-existent, so here too there is a chance that we will receive a new multimeter that, due to some production problems, does not meet the expected parameters. Such multimeters also have other shortcomings. For example, the mentioned Aneng AN870, despite good parameters, has "shallow" sockets. So better cables, e.g. Brymen/Fluke, etc., do not fit it.

author: J-R
author_rank: Super Contributor
timestamp: July 07, 2023, 08:19:40 am
content: The International Vocabulary of Metrology (VIM) was first published in 1984 and has had many revisions since. The VIM of course pushes the separate definitions of calibration and adjustment among other specific terms, but it's not a guarantee that everyone just adopts such things immediately. Plenty of older manuals consider calibration to include adjusting the instrument if necessary, and I still see this used in modern times as well:https://www.ianjohnston.com/index.php/onlineshop/handheld-precision-digital-voltage-source-2-mini-detailSo probably best to not get too bent out of shape on it.I personally try to stick with the terms the manual states when discussing that product or repairs, just to be consistent.But otherwise I'm happy to explicitly state such things as calibration/adjustment/data or etc. just to be clear.With that in mind, my understanding of the DMMCheck Plus "re-calibration" procedure is: an adjustment of the voltage reference to be as spot-on as possible; a small drop of adhesive is applied to the trimmer pot; gather measurements of all references/standards; data printed. I have never seen the "as-received" calibration data for the voltage reference but I am pretty sure they do perform that and perhaps it is available upon request.The "recalibration" of the DC voltage references from VoltageStandard.com is also the same. All the references are tweaked to be as close to the desired value as possible before being sent back to the customer.

author: mendip_discovery
author_rank: Super Contributor
timestamp: July 07, 2023, 01:33:36 pm
content: Things like this are handy as a check, much like if you use a weighing scale to measure products all the time it's handy to have a calibration weight to check it monthly/weekly etc. Engineers keep gauge blocks handy as a way of checking tools.I would be happy to use a unit like that to check a home multimeter of 5.5 digits or less. It might be a bit of a challenge for a 6.5 or 8.5 as they are much better than the specs of the DMMCheck.There is nothing worse than having 2 meters disagree on a measurement to the point where it's hard to determine if it's the thing you are measuring or the kit you are using. Having a sanity check comes in handy then.Cheap vs Expensive, my experience has been expensive 1 out of 10 might have an issue or two, but a cheap meter 1 out of 10 might actually be rather good. YMMV. As I noted the other day the RS-14 is rather crappy when its battery starts to get low, even though it doesn't tell the user.

author: bdunham7
author_rank: Super Contributor
timestamp: July 07, 2023, 03:16:21 pm
content: Quote from: J-R on July 07, 2023, 08:19:40 amFWIW, Doug puts the as-received value on the certificate as well.

author: Martin72
author_rank: Super Contributor
timestamp: July 07, 2023, 03:29:26 pm
content: Quote from: Martin72 on July 04, 2023, 06:49:45 pmHas arrived...Tests will follow in the next days, with my brymen BM869s, East Tester ET4410 LCR Bridge and.....Two scopes, a 8bit and a 12 bit from siglent(SDS1104X-E and SDS2504X HD which is known for it´s accuracy)Could be interesting..

author: mendip_discovery
author_rank: Super Contributor
timestamp: July 07, 2023, 04:58:32 pm
content: Do some tests, and record the results. Do it again ina few months. Compare it to another TEA victim nearby. If you can find a nice lab that will do calibration for sensible money in the future do it and you can build up some confidence in the unit.Thanks for sharing the cert btw. I like to see what others do.

author: tomud
author_rank: Regular Contributor
timestamp: July 07, 2023, 05:46:48 pm
content: Quote from: mendip_discovery on July 07, 2023, 01:33:36 pm6 and 1/2 digits is ok, 8 and 1/2 digits make absolutely no sense. While buying such a multimeter is real, keeping it in good condition, including calibration, is not easy fun. These are high costs, not all laboratories can calibrate such an 8 1/2 multimeter. On the other hand, buying 8 and 1/2 of some old one, which has no known accuracy, does not make any sense. Well, unless I just boast that I have such a multimeter.In fact, if I wanted to become independent, I'd build my own real calibrator, although it's expensive fun. Right now it's cheaper for me to calibrate my 6 1/2 digit multimeters (non-ISO 17025 certified) - as it's not terribly expensive. However, as standards in my home laboratory, they are sufficient - I absolutely do not need 8 1/2 digits to calibrate a multimeter bought for around 200 euros (6 1/2 is fully sufficient).

author: Steve77
author_rank: Newbie
timestamp: July 07, 2023, 06:04:31 pm
content: Quote from: J-R on July 07, 2023, 08:19:40 am

author: alm
author_rank: Super Contributor
timestamp: July 07, 2023, 08:29:05 pm
content: Quote from: tomud on July 07, 2023, 05:46:48 pmAdjustment is actually quite straight-forward for a certain popular 8.5 digit meter (3458A), all it requires is a good short, an accurate 10 kOhm resistor and an accurate 10 V source. Costs about €130here(forum user AP). That's actually much easier than adjusting something like a HP/Agilent 34401A which requires a whole bunch of voltages, currents and resistances to calibrate and adjust it.Resolution, stability and linearity has value beyond accuracy. For example, you might compare two resistors by putting them in series, putting a voltage across them and then comparing the voltage across the two resistors. If the meter has good short term stability and linearity, you can measure the ratio of the two resistors very accurately without needing any absolute accuracy.Quote from: tomud on July 07, 2023, 05:46:48 pmNo argument there

author: Martin72
author_rank: Super Contributor
timestamp: July 07, 2023, 08:38:31 pm
content: I have already tried something, the L/C/R section.The meter was the ET4410 (LCR Bridge).This is exactly how I imagined it, I now have a reference with which I can compare different devices, this makes things easier in the future.The next device will be the Brymen 869s, then possibly the Oscilloscope, a Hioki LCR, and so on.I will always post here.

author: tomud
author_rank: Regular Contributor
timestamp: July 07, 2023, 08:40:25 pm
content: Quote from: alm on July 07, 2023, 08:29:05 pmI'm talking about a normal approach according to the art, not trying to figure out how to do it cheaply. You don't have standards a class above an 8 1/2 digit multimeter your approach is just for fun, not a serious approach to calibration. That's why I prefer calibrated in an accredited 6 and 1/2 lab which is relatively cheap than pretending to calibrate and validate an 8 1/2 digit multimeter at home.I had the opportunity to buy an 8 1/2 digit multimeter but I didn't because it makes no sense to pay such large amounts for calibration in an accredited lab for something that I don't really need at home. Because seriously, explain to me the need to have 8 and 1/2 digits in the house? Unless we are collecting equipment, but it will only be a collection like in a museum - not a reliable measuring instrument.So I still have more faith in the old Agilent 34401A and the newer Keysight 34465A that have up-to-date calibration from an accredited lab. Now the new Siglent SDM3065X has arrived, which will also be sent to the laboratory in a while (when the Siglent calibration period is over). Although to be honest, instead of the SDM3065X, I wanted to buy a second Keysight 34465A first. However, the currently unfavorable exchange rate of the Polish currency and the lack of availability of Keysight 34465A made me take a risk with the purchase. I decided to give DMM Siglent a chance (I don't know if it was a good choice, we'll see after a long time). Unfortunately, in such a combination, I doubt that the uncertain DMM 8 and 1/2 would be better (without current calibration in an accredited laboratory).

author: KungFuJosh
author_rank: Super Contributor
timestamp: July 07, 2023, 10:13:03 pm
content: Quote from: Martin72 on July 07, 2023, 08:38:31 pmI started running through my LCRs with SMD resistors. It takes a long ass time. I will definitely be getting something like that device in the future. I saw on their website about some new high accuracy device coming soon.

author: Martin72
author_rank: Super Contributor
timestamp: July 07, 2023, 10:51:40 pm
content: Hi Josh,How about to buy the L/C option board ?It´s passive, so you don´t need the "rest"..https://dmmcheckplus.com/shop/ols/products/lc-boardMeanwhile I remember of my third LCR meter I got, a mastech MS8911 smart smd tester with testfrequencies up to 10khz..Must check it too.

author: jchw4
author_rank: Regular Contributor
timestamp: July 08, 2023, 01:51:32 am
content: Quote from: Martin72 on July 07, 2023, 03:29:26 pmYou skipped the most interesting part of the certificate: the bottom. But let's look at my case.I bought my DMMCheckplus long time ago from Doug. And sent it back for calibration several times.But then at some point I wanted to get an L/C-board. So I decided to give the new brand owner a try and sent my device for recalibration and adding a new board.Here you can compare the two calibration reports that I got: the previous one from Doug and the new one from the new brand owner.First, the new report lacks the "as received" measurements.All the previous reports showed slight drift of the DC reference value. Now it is simply missing the significant digit.I asked the new owner whether they did any adjustments and they said they did. Which means the history is already lost too.The damage was done.The new cert even has a funny "DCV temperature coefficient" measured +6uV/F but the value measured was specified to the hundreds of microvolts! Was it a joke?Looking further, many (most?) of the values lost at least one significant digit. Starting from AC voltage and current.My AC current has not drifted a single 10^-4 for several years, but now they simply specified it to 10^-3.From the previous calibrations I know that my 1kOhm resistor used to drift for 0.01ohm annually (1.00023k, next year 1.00024k) but there is no that last digit anymore.Low and high oscillator duty cycle was never the same for me. They are suspiciously equal in the new report. And one digit is lost.So I feel that the new cert is basically saying "in specs" and does not give any more details. Which is a very different product from what Doug created.The attention to details is what built trust in this product. Now it is different. And I feel that the new owners are basically reusing old product reviews (see the happy Doug customers above).I would not apply Doug's reputation to the new product. It's not what it used to be.But why dream of what was gone? New age, new trust, new products! Don't be the old guy!Let's look at the new product built by these guys. The L/C board.https://dmmcheckplus.com/shop/ols/products/lc-boardstill says:QuoteGreat! 0.05% is a pretty high margin. What did they use to measure it? BK 891.It's a nice meter, but 0.05% is the very best accuracy it can provide. BK Precision even makes a special "LCR Accuracy Calculator" software to calculate the actual measurement accuracy.Page 6 of the datasheethttps://bkpmedia.s3.us-west-1.amazonaws.com/downloads/datasheets/en-us/891_datasheet.pdfspecifies the basic accuracy, but the user manual has the actual formulas and their software is capable of calculating the actual accuracy.For example, if I read this chart correctly the basic accuracy for a 1uF capacitor measured at 10kHz with this meter is on the edge between 0.5% and 1%.So it was worth asking about the measurement accuracy of their setup, wasn't it?And... they replied me with the chart above. Saying that "BK lays it out on this chart". And attached the chart. That was it.Which basically means they do not have more data and probably never paid attention to.To sum it all up: I think it's unfair to reference Doug work on this product anymore. The attention to details and confidence was the product that Doug built. (And hopefully he is still doing good with his voltagestandard references!)The schematics is not complicated, you can easily build one yourself. You can even measure it with some random calibrated meter, but it won't get you the Doug experience and passion.

author: KungFuJosh
author_rank: Super Contributor
timestamp: July 08, 2023, 02:13:18 am
content: Quote from: Martin72 on July 07, 2023, 10:51:40 pmI emailed them asking what the fancy new device is supposed to be. I'll likely either get the new thing, or just order the whole kit. It will take significantly less time than fussing with the SMD fixture and stuff I have right now...which isn't certified or anything anyway.

author: J-R
author_rank: Super Contributor
timestamp: July 08, 2023, 03:03:12 am
content: Quote from: bdunham7 on July 07, 2023, 03:16:21 pmYes, that is correct. My statement was aimed at the point that "calibration" included an adjustment, unlike the strict definition from the VIM.

author: bdunham7
author_rank: Super Contributor
timestamp: July 08, 2023, 03:11:10 am
content: Quote from: jchw4 on July 08, 2023, 01:51:32 amI don't want to pile on or suggest the DMMCheck+ is a bad value or inadequate for it's obvious intended purpose (which IMO doesn't include calibration or precise checking of meters past the 4.5 digit mark), but as for the detail part here's the link to the calibration certificate for their 3458A.https://img1.wsimg.com/blobby/go/c544540f-524c-4b38-8d0c-cbfda88bf37a/downloads/2022%203458A%20Calibration.pdf?ver=1688384167316

author: J-R
author_rank: Super Contributor
timestamp: July 08, 2023, 04:24:07 am
content: I have the original calibration cert from the DMMCheck Plus I purchased from Doug in 2018 and it only has the DCV listed to the 100uV, no further. I would make the guess that by that point he decided the extra digits can provide a false impression to the customer, so he reduced the resolution to make it clear what can be reasonably trusted and what can't, especially in between calibrations.The voltage references are designed to be adjusted, that is why there is a trimmer pot installed. If you want something different, the metrology forum is full of folks running references and tracking standards for years straight, noting every tiny fluctuation. The DMMCheck Plus is just not a good solution for this. The passives aren't good enough and nothing is sealed so you can bump things with your fingers, probes, etc. The PDVS2mini is the superior voltage reference, but you'll pay $400USD for it.I am not seeing the point of an "as-received" for the passives!If Doug thought the current owners of the DMMCheck Plus were no good, I'm confident he would not have their web site address plastered across the top of his own web site. But I don't see the point in idolizing Doug either. At the end of the day, Doug and Russ are selling hobby products. If you want to be serious, then buy the serious stuff for tens of thousands of dollars and forget these "toys", relatively speaking.When I received my L/C board I did notice the fact they were using the BK 891 and wasn't super-impressed. But on the flip side DMMs and LCR meters are known to use different test methods so it's already going to be a tricky situation to get useful numbers.100% agree with regard to the "all tested to within .05% of their value" on the L/C board description. I think there was just a misunderstanding on their part. Now that the issue is out in the open, I'm sure it will be addressed.

author: jchw4
author_rank: Regular Contributor
timestamp: July 08, 2023, 04:43:13 am
content: Quote from: J-R on July 08, 2023, 04:24:07 amMy original cert is from 2018 too. And it lists DCV to the 100uV too. But later recalibration certificates are more precise. So I would guess the opposite.QuoteSure. I just demonstrated the two certificates that present attention to details.QuoteTo me the main issue is ignoring the tool specification that they base their claim on. I wonder what Martin's cerificate says about the meter though.QuoteAre you serious?

author: J-R
author_rank: Super Contributor
timestamp: July 08, 2023, 05:38:54 am
content: My first cert is from December 2018 (Doug), next cert is from March 2020 (Russ), neither have more than 100uV, nor do subsequent ones.Not sure about your comment regarding my comment to the issue being out in the open. You said you e-mailed them but they blew you off or whatever, but now you've pointed it out in the forums for everyone to see and we agree with you. So we should expect them to have to deal with it at some point.

author: jchw4
author_rank: Regular Contributor
timestamp: July 08, 2023, 06:18:36 am
content: Quote from: jchw4 on July 08, 2023, 04:43:13 amI feel that I look too aggressive here, but this story just blew me away.But let me explain which details I had in mind here.As you can see from my certificate from Doug, these references are often more stable than stated. I.e. both "before" and "after" DCV values start with "5.0000".To see the behavior of the reference you need to get into the unstable area, this is why (at least) the next digit is important.But it is also only important if stated before and after the adjustments too. This way I could estimate how precise my measurements were just before sending it for recalibration.If it was "5.5000" before the adjustments I would need to double-check what I did just before sending it for recalibration. If it was "5.00001" - probably not.I have only one DMMCheckplus, so I don't have the total statistics, but looking at the annual stability of all the values, losing the "before adjustments" part and a significant digit is a major loss.I believe they should know that stability of the values are often better than what they measured.So I am not saying it is not useful or suitable for this or another purpose. I am just saying that it's a different product now.Before I could predict the actual value, now I am not sure. There is no information on where the uncertainty area of this particular reference starts.It used to be a reference (not extremely precise, but with known behavior), now it's just "Check your DMM pass/fail".The device price is still good, so I would recommend the hardware itself (but I don't have a new version, so I just hope they did not "improve" the hardware part). Hopefully it's just the measurements setup that is now different.QuoteIf you noticed the issue with the L/C board too, then it's fair to assume that we are not alone and many other people have also noticed it.Do you mean that the issuehasto go public to be addressed?QuoteNo, they did not. We had a very polite discussion. I just learned that they could not provide the data that I needed and stopped.I don't see any point arguing with them because the lost data won't magically come back, and my knowledge is definitely less than theirs. They want their product to look like this for some reason, whatever.My point is just that the prior Doug-era experience may not be relevant to the current device. So when comparing it to cheap Chinese references we should not take prior experience into account.

author: Martin72
author_rank: Super Contributor
timestamp: July 08, 2023, 05:55:11 pm
content: Today my Brymen BM869s..

author: tomud
author_rank: Regular Contributor
timestamp: July 08, 2023, 06:23:18 pm
content: Quote from: Martin72 on July 08, 2023, 05:55:11 pmChinese reference voltage for a few dollars, on a relatively poor AD584

author: Martin72
author_rank: Super Contributor
timestamp: July 08, 2023, 06:40:27 pm
content: Looks good.

author: bdunham7
author_rank: Super Contributor
timestamp: July 08, 2023, 07:03:59 pm
content: Quote from: J-R on July 08, 2023, 04:24:07 amIMO the 891 is more than adequate for this type of low-cost standard given it's objectives and the fact that it is on a small PCB and not some sort of fixture. The only problem is the 0.05% claim--that's not an easy spec to meet even at much higher cost. They need to get real about that, although there will be howling if they revise it downwards.The issue of DMMs and LCR meters giving different results due to the differences in their test methods is a result of the type of capacitor used. A very high quality, low-D, low-ESL/ESR and low leakage unit--polypropylene, polystyrene, wet tantalum or silver mica--will give similar results on different instruments and to an extent, with different test frequencies.

author: Martin72
author_rank: Super Contributor
timestamp: July 08, 2023, 07:48:22 pm
content: I hope that it is clear to everyone that neither this "reference" nor any other, even cheaper to get, are to be used seriously for calibration purposes.You can use them as a comparison, as a kind of guide.But regular what calibrate or adjust with it, in this state, you should leave it, if you take the matter seriously.Sure, if you need something accurate to 2..3 digits, then that may be enough.But actually a reference must be unequally "better", more accurate, more stable.At work, we thought for many years that we could calibrate some of our measuring instruments ourselves, because we have measuring equipment calibrated according to ISO.Until auditors once taught us otherwise, and they were still friendly about it.All this was of no value.To be able to calibrate according to ISO, the references must have a higher calibration standard.That is, e.g. calibrated according to DakkS (very expensive).And even then it would not be valid, because we have no accreditation for being able to calibrate something according to the standard and bring it into circulation.So...That's why this little piece of paper that came with the device is hardly worth anything.At least until I have it calibrated again and then by an accredited laboratory (and then it depends on what means they have used for calibration).This costs about the same if not more than the device itself, so I still have to think very well.Until then, I use it as something with which I can quickly compare devices with each other and that's already good.

author: 4thDoctorWhoFan
author_rank: Regular Contributor
timestamp: July 08, 2023, 08:03:51 pm
content: I have one and I mainly use it for a sanity check. Because sometimes you need a sanity check.

author: KungFuJosh
author_rank: Super Contributor
timestamp: July 08, 2023, 10:29:11 pm
content: Quote from: 4thDoctorWhoFan on July 08, 2023, 08:03:51 pmThat statement next to your profile picture is pretty funny. 😉

author: 4thDoctorWhoFan
author_rank: Regular Contributor
timestamp: July 08, 2023, 10:32:30 pm
content: Quote from: KungFuJosh on July 08, 2023, 10:29:11 pmYep! You got that right.

author: Martin72
author_rank: Super Contributor
timestamp: July 08, 2023, 10:39:18 pm
content: I must smile a little bit as I recognize what LCR they have used to measure the L/C board.A BK891..https://de.rs-online.com/web/p/lcr-messgerate/1217581Our calibrated ST2830 also have 0.05%, so I´m curious about the results when I take the box to work on monday.

author: Fungus
author_rank: Super Contributor
timestamp: July 09, 2023, 12:43:17 am
content: Here's my $5 Aliexpress special against my two best meters:

author: KungFuJosh
author_rank: Super Contributor
timestamp: July 09, 2023, 01:09:13 am
content: Quote from: Fungus on July 09, 2023, 12:43:17 amGot a link for that one? I can't find it.

author: Fungus
author_rank: Super Contributor
timestamp: July 09, 2023, 03:36:22 am
content: Quote from: KungFuJosh on July 09, 2023, 01:09:13 amThe sticker says I bought it in 2017 so exact models have changed since then.Today's equivalent is probably this:https://www.aliexpress.com/item/32658819804.htmlThe ad says "10. Each board at the factory to be detected with Aglient 6 digit multimeter, and marked with the output voltage, user-friendly."(nb. Random seller...I have no idea if they're good but they've sold 65 and got good reviews)

author: Shonky
author_rank: Frequent Contributor
timestamp: July 09, 2023, 04:53:50 am
content: AD584LH on the linked one is likely fake on these as they haven't been made in quite a while - 10 years or more. The picture does show a 1223 date code, but well... you know...Some of the pictures show terrible quality and indicate they don't include any "cal data"

author: Fungus
author_rank: Super Contributor
timestamp: July 09, 2023, 06:57:49 am
content: Quote from: Shonky on July 09, 2023, 04:53:50 amI think they're likely to be second hand chips pulled out of old devices.(i.e. well burned-in)Quote from: Shonky on July 09, 2023, 04:53:50 amIf they send garbage you can just open a claim and get your money back. It's easy.(I have no idea where people see "risk" on Aliexpress. Returns and refunds are just as easy as Amazon - you don't like something? Just get your RMA barcode and drop it off at the kiosk on the corner, no questions asked...)

author: tomud
author_rank: Regular Contributor
timestamp: July 09, 2023, 09:31:36 am
content: Quote from: Fungus on July 09, 2023, 03:36:22 amThis is just a description, and the photos in the comments clearly show that there is no voltage measurement sheet attached. When I was buying mine, I had to do some research at auctions to find one with a handwritten card, because there were also printed cards where all the copies sold had the same voltage values (cheating).Currently, in the same way, you have to look in the photos attached in the comments if there is a sheet with voltage measurements.Here, for example, there is a comment that the PCB is described, but there is no message with what accuracy. On the other hand, in other auctions I have seen descriptions only up to the third decimal place.https://www.aliexpress.com/item/1005004617368378.htmlhttps://www.aliexpress.com/item/1005004186281432.htmlHere again you can see on the printed sheet - but it's hard to tell if these are real voltage measurements (too small photo in the comment).https://www.aliexpress.com/item/1005005609015568.htmlHere again the version I have in the acrylic housing, in one comment there is information about the attached voltage measurements.https://www.aliexpress.com/item/32813473384.htmlHere again versions with LM399:https://www.aliexpress.com/item/1005002791469664.htmlBut these are just examples of found auctions and I am not sure about the quality of the offered goods.Quote from: Fungus on July 09, 2023, 06:57:49 amYes, in mine there is a 100% old chip desoldered from some device, you can see it by the condition of the metal housing.

author: Fungus
author_rank: Super Contributor
timestamp: July 09, 2023, 10:40:48 am
content: Quote from: tomud on July 09, 2023, 09:31:36 amMy sheet was stuck to the bag it came in (see pic).But yeah, I just picked that seller because the sold a lot and had a good rating. If you go through all the reviews there's a couple that say there's no "passport" so maybe that's not the one to get.Get one that clearly shows numbers in the listing photos so you can reclaim easily if it doesn't have them. :-)

author: tomud
author_rank: Regular Contributor
timestamp: July 09, 2023, 11:40:00 am
content: Quote from: Fungus on July 09, 2023, 10:40:48 amThat's all I knowThat's why I looked at the pictures in the package and I didn't notice that the voltage measurements were glued to the bag. And of course, information in the comments about the lack of voltage measurements:"Everything works. Asked the seller to put a passport of factory measurements, but whether he forgot, or scored, or he does not have that. Ignored the request in short. Did not answer anything. Measured on a precision voltmeter-all in admission.""There is no passport for the microcircuit and no factory control measurement. What exactly voltage gives out and how to calibrate something with this voltage is not clear. In general, within the margin of error in the dataite, The microcircuit fits well. For instruments with 2 decimal places will come down."btw there are still such "reference modules" RLC availablehttps://www.aliexpress.com/item/33040571353.html

author: Veteran68
author_rank: Frequent Contributor
timestamp: July 09, 2023, 08:28:58 pm
content: Quote from: Fungus on July 09, 2023, 03:36:22 amThis is the one I mentioned earlier I have that takes the wonky 15V battery, unless you use a DC barrel jack (which is what I do now after buying a couple of those expensive batteries). Mind did come with the highly desirable AD584LH version of the reference. Obviously pulled from something.Mine came with a "cal" sheet as shown. Haven't used it in forever, just checked and measured 5.00112 and 10.00183 with my 34401A. Not too bad I guess for 8 years old, if that cal date is even accurate. But the fact they went to the trouble to type & print this cal sheet makes me suspicious that they just printed off a bunch and stick the same one in each shipment, lol.

author: Shonky
author_rank: Frequent Contributor
timestamp: July 10, 2023, 12:47:55 am
content: Quote from: Veteran68 on July 09, 2023, 08:28:58 pmThere are some suppliers that definitely were supplying the exact same printed sheet similar to that one with every unit. The ones that come with hand written sheets appear to be more genuine.The ones that actually are tested seemed to be closer to their cal sheets than yours is.

author: Fungus
author_rank: Super Contributor
timestamp: July 10, 2023, 02:10:44 am
content: Quote from: Shonky on July 10, 2023, 12:47:55 amI've seen that cal sheet before...https://www.eevblog.com/forum/metrology/are-cheap-ad584-units-worth-it/msg920924/#msg920924

author: rsjsouza
author_rank: Super Contributor
timestamp: July 10, 2023, 02:18:01 am
content: My unit came with a hand written sticker and it has been quite stable over the years. I can't complain for throwaway money. The AD586 device on it is clearly re-used from somewhere else but, as Fungus mentioned, it gives more confidence the initial drift has been surpassed and the unit is much more stable.

author: all_repair
author_rank: Frequent Contributor
timestamp: July 10, 2023, 02:29:38 am
content: Quote from: Fungus on July 09, 2023, 06:57:49 amOld volt-nut chips are much sought after item in the Chinese volt-nut community. It is a desirable feature as that means it is a much stable chip that shall have lesser drift later.Checkup the price and availabilty of the new chip and you shall see the makers are doing a great service. And the literature are in Chinese show that these goods are meant for, and by, the local volt-nut community

author: Veteran68
author_rank: Frequent Contributor
timestamp: July 10, 2023, 02:45:00 am
content: Quote from: Fungus on July 10, 2023, 02:10:44 amI'm shocked, SHOCKED!, I tell you!I knew when I got it that there was no way they were typing up, printing, and cutting out each of these for each unit. The handwritten ones are much more believable.

author: Fungus
author_rank: Super Contributor
timestamp: July 10, 2023, 02:53:33 am
content: Quote from: Veteran68 on July 10, 2023, 02:45:00 amYep.Mine actually seems to have a transcription error.Attentive readers might have noticed I didn't post the 7.5V reading in the previous post:Everything I've ever measured it with has shown around 7.506V so I think whoever wrote the number on the sticker inserted an extra zero by mistake (there's usually two zeros after a '5', right?)To me it makes it even more authentic.

author: Fungus
author_rank: Super Contributor
timestamp: July 10, 2023, 03:03:08 am
content: Quote from: Veteran68 on July 10, 2023, 02:45:00 amThe date on it should be a giveaway. When did you buy yours?

author: mawyatt
author_rank: Super Contributor
timestamp: July 10, 2023, 03:19:27 am
content: Some folks might find these interesting.Here's some DIY voltage references based upon LM399, LTZ1000 and some others, also a means to produce an accurate AC rms waveform.https://www.eevblog.com/forum/projects/building-a-calibration-device/msg3485874/#msg3485874https://www.eevblog.com/forum/projects/diy-dvm-simple-dvm-cal-device/msg4576009/#msg4576009https://www.eevblog.com/forum/testgear/ac-rms-dmm-tests/msg3940957/#msg3940957Best,

author: KungFuJosh
author_rank: Super Contributor
timestamp: July 10, 2023, 03:23:03 pm
content: I emailed DMMCheck about their fancy new higher accuracy product, and this was their response:"Thank for your interest in our products. When available, the new higher stability model will be higher in price but will include all options. The current model you pick and choose options which affects cost. The new LT1021 has higher stability due to the unit being always on and no longer being exposed to ambient air. I hope this helps."

author: Martin72
author_rank: Super Contributor
timestamp: July 10, 2023, 08:31:37 pm
content: Today I test our ST2830 at work with the L/C option and resistance of the DMMCheck.Put the results to the table I´ve made for the ET4410 from East Tester.Remarkable: Both meters have their runaways in the same places, is that still coincidence....I think I will have the checker calibrated externally after all.

author: Martin72
author_rank: Super Contributor
timestamp: July 11, 2023, 03:40:48 pm
content: Ref.Voltage measuring, DC, AC100hz, AC10khz all with the SDS1104X-E from siglent, the SDS2504X HD will soon follow.Have a look at the statistics(at ac, dc was too short)....nice.

author: alm
author_rank: Super Contributor
timestamp: July 11, 2023, 07:08:03 pm
content: Quote from: Martin72 on July 11, 2023, 03:40:48 pmThanks for the measurements. I'm surprised by the droop in the AC 100 Hz signal showing a high pass effect. I'd expect them to generate a square wave at very close to the reference amplitude with the idea that the fewer components contribute to the output signal, the fewer components that can drift. Now any temperature-dependent effect in the coupling capacitor will effect the output.

author: KungFuJosh
author_rank: Super Contributor
timestamp: July 11, 2023, 07:49:06 pm
content: Quote from: alm on July 11, 2023, 07:08:03 pmThat seems relevant given what claims they made about the new device they're releasing.

author: Martin72
author_rank: Super Contributor
timestamp: July 11, 2023, 08:14:00 pm
content: At the moment my SDS2504HD measure the same signal - without "deforming"...Must investigate this.

author: alm
author_rank: Super Contributor
timestamp: July 11, 2023, 08:47:32 pm
content: Quote from: Martin72 on July 11, 2023, 08:14:00 pmThe SDS1104X-E was not set to AC coupling, was it?

author: Martin72
author_rank: Super Contributor
timestamp: July 11, 2023, 08:56:54 pm
content: Look at the pics, right side..Meanwhile I did several measures with the HD, with probe, without probe, everytime fine and looks great, post the pics soon.But now I´m turning the SDS1104X-E on again, want to know what´s going on.

author: bdunham7
author_rank: Super Contributor
timestamp: July 11, 2023, 09:01:57 pm
content: Quote from: alm on July 11, 2023, 08:47:32 pmI think this is a known issue with the scope at low frequencies.Here's 100Hz 10Vp-pfrom SDG2042X direct to SDS 1104X-E with settings as shown.

author: Domitronic
author_rank: Regular Contributor
timestamp: July 11, 2023, 09:12:53 pm
content: Quote from: bdunham7 on July 11, 2023, 09:01:57 pmYes, at least my SDS1104X-E has the same issue:https://www.eevblog.com/forum/testgear/siglent-sds1204x-e-released-for-domestic-markets-in-china/msg4433131/#msg4433131Others reported the same in this thread.

author: Martin72
author_rank: Super Contributor
timestamp: July 11, 2023, 09:13:07 pm
content: Yepp, it must be an issue - connect the signal directly without a probe to the scope, no changes.Hmm..Not so nice for SDS1104X-E owner.

author: Veteran68
author_rank: Frequent Contributor
timestamp: July 11, 2023, 09:19:00 pm
content: Quote from: Fungus on July 10, 2023, 03:03:08 amHad to search email history to figure out where and when I bought it.EBay, Feb 2020. So yeah it came with 5yo cal sheet from some other device (if not entirely made up numbers to begin with).I had bought a few different varieties of these cheap ones, like the other ones pictured in this thread, but this one was an odd duck with its battery requirement so after I was done playing with it, it went into a drawer and was never used again.Since then I bought a LB02A process calibrator which is handier and more fun to use, and is really all the reference I need for my hobby purposes.

author: Martin72
author_rank: Super Contributor
timestamp: July 11, 2023, 09:32:11 pm
content: Now the SDS2504X-HD...You musn´t buy this to get the nice histograms, you could have them with a unlikely more cheaper SDS2000X-Plus.But the accourate DVM, you get it only with the 12bit model.

author: KungFuJosh
author_rank: Super Contributor
timestamp: July 11, 2023, 10:08:06 pm
content: I love the details on the HD's measurements.

author: Martin72
author_rank: Super Contributor
timestamp: July 12, 2023, 08:21:33 pm
content: Quote from: Martin72 on July 07, 2023, 10:51:40 pmDid it, it´s not too bad...Testfrequency 10khz..(reference)1050 µH (1032µH)104.8µH (104.3µH)10.5µH (10.52µH)1µH (1.061µH)1.017nF (1.019nF)10.14nF (10.16nF)102.3nF (102.5nF)1.013µF (1.001 µF)DCR100.0 Ohm (100.058)0.999 kOhm (0.9994)9.999 kOhm (9.9995)100.0 kOhm (100.017)

author: tatel
author_rank: Frequent Contributor
timestamp: July 13, 2023, 07:21:15 am
content: Now that I got this thing and almost half a dozen multimeters, I reckon it's time for me to work out some spradsheets. So here it's my first try at it. All I can say it seems to work. But, since I really don't know what I'm doing, please feel free to criticize it sharply and maybe even use it

author: Martin72
author_rank: Super Contributor
timestamp: July 13, 2023, 11:46:03 am
content: Hi,I have taken the liberty of making it more visible, your notes on the sheet as a quote:QuoteHere my BM869s results:https://www.eevblog.com/forum/testgear/dmmcheck-plus-multimeter-calibration-reference-experiences/msg4950205/#msg4950205Interesting thing with the dual display, must check this too.L/C values: Indeed it´s only measured with a device which got 0.05% basic precision.

author: Martin72
author_rank: Super Contributor
timestamp: July 13, 2023, 04:21:43 pm
content: QuoteIndeed, according to the manual single mode display is only avaible in DCV mode, also the 500000 counts.Only when DCV, nothing else.

author: tatel
author_rank: Frequent Contributor
timestamp: July 14, 2023, 12:54:01 am
content: Quote from: Martin72 on July 13, 2023, 04:21:43 pmWhat looks strange to me is that 11 counts difference between DCV in dual mode vs single mode in 50000 counts mode. I mean, shouldn't be the involved guts be almost exactly the same? turning on some more led segments is enough to get a 0.02% difference?Not that I care so much about it, but I was expecting it to read exactly the same in both display modes.

author: J-R
author_rank: Super Contributor
timestamp: July 14, 2023, 02:42:36 am
content: Frequency measurements are possible in ACmA mode on the BM869s, but it may not display at very low currents.Also, you can only calibrate DCV and ACV ranges, not any of the combined modes. The readings in combined mode can be up to 80 counts off.I didn't have time to dig further to see what is causing the error. I think I will calibrate the ACV mode and see if that impacts it.

author: bdunham7
author_rank: Super Contributor
timestamp: July 14, 2023, 02:47:09 am
content: Quote from: tatel on July 14, 2023, 12:54:01 amOn most meters with dual-display modes they still only have one ADC so they can't measure simultaneously. When they switch back and forth between modes, the meter may not be able to settle quite as fully as it would in the single display mode. This slight (or in some cases not-so-slight) degradation happens with almost all meters with these dual modes.

author: tatel
author_rank: Frequent Contributor
timestamp: July 14, 2023, 07:31:29 am
content: Quote from: J-R on July 14, 2023, 02:42:36 amThank you. Seller has about the same opinion. I measured ACV on the "I" outputs of DMMCheck, got about 0.5V. Then I measured ACmA on the "V" terminals, so 5V. I got a good 100 Hz and 10 kHz readings at about 28mA.So it turns out this DMM works fine and DMMCheck+ output is somehow too low on the "I" terminals for it to read Hz on the mA mode.

author: Martin72
author_rank: Super Contributor
timestamp: July 14, 2023, 09:27:01 pm
content: Got an answer from welectron about additional calibration of the DMMCheck plus.Will cost about 85€, pro would be a "real" calibration according to ISO standards, including a report - I already knew it from my brymen.Con: 85€...Will sleep about it, then decide.

author: KungFuJosh
author_rank: Super Contributor
timestamp: July 14, 2023, 10:45:24 pm
content: Quote from: Martin72 on July 14, 2023, 09:27:01 pmFor 25€ I can scribble out the AD584 and doodle in DMMCheckPlus on this paper, and it will be just as useful. 😉

author: Martin72
author_rank: Super Contributor
timestamp: July 14, 2023, 10:53:38 pm
content: Such "scraps" of paper do not interest me at all, because completely worthless.There is even the option to have the checker calibrated according to DakkS...But then it becomes three-digit in terms of price.That does not have to be, for the hobby.

author: KungFuJosh
author_rank: Super Contributor
timestamp: July 14, 2023, 11:55:00 pm
content: That's my point. 😉Since this is just for hobby use, and it already has some level of calibration, do you really benefit from spending more money on calibration? I'd save that cash and spend more money on their new improved model. 😉😉

author: Martin72
author_rank: Super Contributor
timestamp: July 15, 2023, 12:12:26 am
content: When it comes with the same sheet of paper it is as useful as the "old" one..And as long as they would use the same reference IC nothing great will change, maybe the stability but this you can check with a period calibration, regardless if new or old version.QuoteWhen I want to know if it´s "true", it should be worth the money.My skepticism started when I realized that the components on the L/C board are not high accuracy types, but only those that were measured with their LCR meters.Then most of the values are rounded.It may be that I am "damaged" by my profession in this respect, but if it is advertised that it should be a device for the calibration of other devices, then it should also be documented extensively.

author: KungFuJosh
author_rank: Super Contributor
timestamp: July 15, 2023, 02:03:44 am
content: Quote from: Martin72 on July 15, 2023, 12:12:26 amI would return it if you don't feel it's reliable or accurate enough. For what you're investing in it plus calibration, you could build your own test board with whatever components & accuracy level you want, and then send the board you made to be calibrated. IMHO that would be a better reference.For me, that would be more entertaining, and less expensive. Hmmm. Maybe I'll make a test PCB for all the SMD stuff I got for calibration. 🤔Edit: aaaand I already drew a schematic for it. Super simple for a passive test board.

author: J-R
author_rank: Super Contributor
timestamp: July 15, 2023, 08:08:17 am
content: Ran some LC tests:

author: Martin72
author_rank: Super Contributor
timestamp: July 15, 2023, 11:18:34 am
content: Ah, the good old DE5000 - Most underrated lcr-meter ever..

author: mawyatt
author_rank: Super Contributor
timestamp: July 15, 2023, 12:42:23 pm
content: Quote from: KungFuJosh on July 15, 2023, 02:03:44 amSomething like these?Which are obviously directed towards bench type DMMs with the 4 banana plugs directly on the PCBs.Edit: Second image came in upside down, so it's measuring Mhos not OhmsBest,

author: mawyatt
author_rank: Super Contributor
timestamp: July 15, 2023, 01:19:50 pm
content: Here you can see the test fixture with another DMM measuring its temperature, altho we haven't found this feature very useful but included such just in case.Best

author: Martin72
author_rank: Super Contributor
timestamp: July 15, 2023, 01:20:34 pm
content: Quote from: KungFuJosh on July 15, 2023, 02:03:44 amRemember my post ?https://www.eevblog.com/forum/testgear/th2830-vs-th2832/msg4957831/#msg4957831

author: KungFuJosh
author_rank: Super Contributor
timestamp: July 15, 2023, 02:16:01 pm
content: Quote from: Martin72 on July 15, 2023, 01:20:34 pmYup. But for me, it doesn't matter. I only care to see if the accuracy drifts over time. And I don't need everything to match for 6 digits; if it's close enough, it's close enough. For you, I'm pretty sure you would want a cal lab to certify values first anyway. 😉Though I don't think I'm going to limit this to SMT stuff. Especially for the inductors where THT gives a better range with more stability.

author: KungFuJosh
author_rank: Super Contributor
timestamp: July 15, 2023, 02:18:33 pm
content: Quote from: mawyatt on July 15, 2023, 12:42:23 pmI'm going simpler than that. Similar to the DMMCheck's L/C board, but covering LCR. Test points for each device, and 1 common for use with kelvin leads in each section.

author: Martin72
author_rank: Super Contributor
timestamp: July 15, 2023, 02:40:11 pm
content: QuoteIn most cases, you don't have the right test frequency, but what you are measuring is enough if it is always measured that way over time.OK, then that's the way it is.

author: KungFuJosh
author_rank: Super Contributor
timestamp: July 15, 2023, 07:40:48 pm
content: Quote from: Martin72 on July 15, 2023, 02:40:11 pmExactly. Check it out, I designed my PCB. 😉

author: Martin72
author_rank: Super Contributor
timestamp: July 15, 2023, 07:54:48 pm
content: Why not ?Could be interesting to measure nH/pf on it.Another voltage/current reference project:https://www.elektormagazine.de/labs/voltage-current-calibrator-0-to-10v-and-0-to-40ma-0001I must confess I was too fast and ordered the PCB by JLCPCB, they´re already on their way.Too fast because did this before looking at the BOM..Several ICs are not avaible before 2024 and then they cost..not less.

author: KungFuJosh
author_rank: Super Contributor
timestamp: July 15, 2023, 08:13:43 pm
content: Quote from: Martin72 on July 15, 2023, 07:54:48 pmWhat chips aren't available on the BOM? I haven't signed up yet, but I probably will. That looks like an interesting project.I'll be ordering extra PCBs of mine too, since it costs less to buy more. 🙄

author: Martin72
author_rank: Super Contributor
timestamp: July 15, 2023, 08:26:08 pm
content: Here the BOM of the reference itself and of the (additional) heater...Minimum 2 of the AD... OP-Amps are missed (Farnell)In principle, you could still "tune" it to 1ppm, but that's another story.You know there´s a 5pcs minimum order so I could send you a pcb, but I think, the shipping costs will be more expensive as if you order them directly..Edit: Threadtitle changed..

author: KungFuJosh
author_rank: Super Contributor
timestamp: July 15, 2023, 08:44:06 pm
content: I can't look through the whole BOMs right now, what specifically can't yet get? There's very likely plenty of substitutes.For example, IH0515SH replace with: PEM2-S5-S15-S

author: Martin72
author_rank: Super Contributor
timestamp: July 15, 2023, 08:58:34 pm
content: AD8676, AD5791 (expensive), AD8675, the rest I didn´t looked for.Nevertheless, not a cheap project. When I decide to start with it, I´ll make a new thread for it.One the cheapest parts would be the pcb...

author: KungFuJosh
author_rank: Super Contributor
timestamp: July 15, 2023, 09:25:42 pm
content: Quote from: Martin72 on July 15, 2023, 08:58:34 pmYikes! The AD5791s in stock are $327 USD. The $85 version is next year, but the $135 version might be as soon as September. Any of those options are pretty expensive for a single chip on a test board.The other two have SMD versions available for $4 to $7. Start the thread anyway. 😉

author: Martin72
author_rank: Super Contributor
timestamp: July 15, 2023, 09:35:14 pm
content: OK, you talked me into it....

author: DavidKo
author_rank: Frequent Contributor
timestamp: August 03, 2023, 08:38:17 am
content: I got mine directly from Doug since 2019. There was a waiting list since it was not available in e-shop. The box I have modeled myself. It includes external power supply connector (the connector disconnect 9V battery when used) and let it run 24/7 from power supply. In case of the power outage it gets turned off, but the main reason is to run 24/7 to burn in the reference. I have alsoAD584 referencewith printed values since 2016, but I have never trusted to the values and when I had better multimeter it was already running 1+ year.

author: DavidKo
author_rank: Frequent Contributor
timestamp: August 03, 2023, 05:06:29 pm
content: My measurements of DMMCheck and original values from calibration. 5,5 digit multimeter do not see any change.

author: DavidKo
author_rank: Frequent Contributor
timestamp: August 03, 2023, 05:11:26 pm
content: When I measured the AD584 it is clear that something stinks, but I must say, that the values are stable.

author: Veteran68
author_rank: Frequent Contributor
timestamp: August 03, 2023, 05:54:52 pm
content: Quote from: DavidKo on August 03, 2023, 05:11:26 pmFunny how that same cal sheet makes it around the world. Wonder how many references it's been shipped with?

author: Martin72
author_rank: Super Contributor
timestamp: August 03, 2023, 09:08:32 pm
content: While I will probably repeat my series of measurements....In the Siglent SDM thread, one criticized that I had contacted the test points on the DMMCheck with probe tips.Better would be, at least for the voltage / current measurement, to solder shielded wires to the test points and connect the multimeters.For fun I had done that yesterday and just quickly connected a multimeter - Hmmm...That is actually a difference,And that's why it will probably be repeated.

author: J-R
author_rank: Super Contributor
timestamp: August 03, 2023, 11:21:20 pm
content: I disagree with the idea of soldering anything to the reference. The first issue would be heat into the PCB from soldering impacting the reference output, and the second would be simply invalidating the current calibration. So naturally there would be a high probability of a difference in the readings after performing this procedure.Currently I have 5 calibrated voltage references and two calibrated 6.5 digit DMMs and I have not observed any issues whatsoever from my choice of probe or connection. The only major factor impacting measurements has been time since power on and ambient temperature.Only with my 7.5 digit DMM am I able to start to begin to observe some of the effects that you have to pay close attention to in the area of metrology, of which I admit I only lightly dabble.

author: KungFuJosh
author_rank: Super Contributor
timestamp: August 03, 2023, 11:45:16 pm
content: I agree, modifying the reference doesn't make sense to me. I would use good quality probes with clips. If possible, I'd use the same probes and clips with every meter you're comparing.

author: J-R
author_rank: Super Contributor
timestamp: August 04, 2023, 02:22:15 am
content: To clarify, even the quality of the probes and clips really doesn't matter at this level.Consider a 5V reference connected to a 10M Ohm input DMM. Current flow is 0.000,5mA. Add 10 Ohms to that circuit to represent a very bad connection and the voltage drop is only 0.005mV. So you would need a 5 million count or better DMM to even see this (typically a 7.5 digit DMM). If your DMM has a > gig Ohm input option at this voltage, then it truly doesn't matter.Consider a 1mA current source from the DMMCheck Plus, which in my sample maxes out just above 500mV. The resistance in the circuit would have to exceed 500 Ohms before it would not be able to generate 1mA. Common DMM shunt resistances are around 2 Ohms for mA and 100 Ohms for uA. Again in this case, adding 10 Ohms for a bad connection will not make any difference.

author: Martin72
author_rank: Super Contributor
timestamp: August 04, 2023, 05:43:39 am
content: QuoteYou shouldn't fry it for minutes, that's right.But I know that too, accordingly short it happened.We will see, if the values have become worse, it was due to the soldering.

author: DavidKo
author_rank: Frequent Contributor
timestamp: August 04, 2023, 07:15:45 am
content: Using the probes is not ideal, you can create the Seebeck effect simply by heating one probe more when holding it.

author: J-R
author_rank: Super Contributor
timestamp: August 04, 2023, 07:59:23 am
content: Quote from: DavidKo on August 04, 2023, 07:15:45 amIt's just not really visible on a 6.5 digit DMM @ 5V. Test leads are well insulated, so the metal tip is not going to be heating up much at all, and if it does, once you start holding it against the terminals the temperature differential will be absolutely miniscule. Maybe if you have soldering irons for fingers.For sure the way to easily see this though is to drop into the mV range and heat the probe tips with your fingers directly. Then the effect is immediately visible.Otherwise as I mentioned you mostly start to worry about such things at 7.5 digit DMMs and above. And really one of the top rules at this level is that your hands are in the next room...

author: KungFuJosh
author_rank: Super Contributor
timestamp: August 04, 2023, 02:11:39 pm
content: Quote from: DavidKo on August 04, 2023, 07:15:45 amQuote from: J-R on August 04, 2023, 07:59:23 amThis is why I saw to use probes with clips/grabbers, so your hands aren't anywhere near the test.

author: J-R
author_rank: Super Contributor
timestamp: August 04, 2023, 05:58:33 pm
content: I experimented and researched a bit more and will still postulate that holding the probes makes no difference in the context we are discussing. The reason this is the case is that you are heating up both probes at the same time, so it cancels out the effect.Furthermore, 5V on most bench DMMs is going to push you up into the next range, so you lose a digit. So even at 7.5 digits, whether you hold the probes or not really makes no difference. I was hard pressed to even see the effect at 1V on my Keithley 2010 when holding one probe tip directly.

author: KungFuJosh
author_rank: Super Contributor
timestamp: August 04, 2023, 07:17:31 pm
content: Quote from: J-R on August 04, 2023, 05:58:33 pmFor the sake of heat, you're probably right. However, relying on hands to hold probes in place consistently gives inconsistent results. Grabbers force contact consistency, and you can run the test 100 times without change to the results based on contact changes.

author: Martin72
author_rank: Super Contributor
timestamp: August 04, 2023, 07:33:01 pm
content: There was a difference if I used the TL leads from fluke or the probemaster from home.It makes also a difference depending on how the probe tips are pressed against the test points, from which side, etc.It is simply not 100% firm contact.As for the clips :For current/voltage it was OK, but for resistors I had more resistance ( albeit in small form) than when I used the probe tips.I don't think the short term soldering brings any disadvantages, differences in ambient temperature are enough to create "more" deviations.Speaking of ambient temperature, I had refrained from performing the measurements until now.By heatrun tests we have in the test field at present approx. 31°C...

author: KungFuJosh
author_rank: Super Contributor
timestamp: August 04, 2023, 08:23:42 pm
content: Quote from: Martin72 on August 04, 2023, 07:33:01 pmThe precise value doesn't matterindependentlywhen you're comparing devices. The only thing that matters is you remove inconsistencies in the testing method. If you use the same probes/clips for all meters, you eliminate the inconsistencies of your test setup. In other words, if the clips you're using altered resistance by .001Ω, it doesn't matter, it will have the same altered value for all devices.If you solder wires on to the reference, you (semi) permanently alter the cal values. Then if you connect with different probes to those leads, you still have an inconsistent test setup.

author: Martin72
author_rank: Super Contributor
timestamp: August 04, 2023, 08:49:42 pm
content: QuoteWhy should I do this..By soldering I have made a better contact, this could well lead to the calibration no longer being correct, if more or less contact-safe clips were used when calibrating, that is true.However, I will soon send the checker with these solid leads for recalibration.Then no one has to worry about it anymore.

author: Martin72
author_rank: Super Contributor
timestamp: August 05, 2023, 10:45:09 pm
content: QuoteOn Saturday we still had 25.5°C, but I was curious....I had already measured last week with the Keysight, for this I had used the test leads from Fluke and it was loosely 4 kelvin cooler in the test field.Here are the values I had measured at that time:DCV: 4.9997VDCA: 1.00049 mAACV: 5.0000VACA: 1.0001 mAFreq.: 100.003 HzThe pictures show the current measured values with the soldered leads and just at 25.5°C.Now you can wonder if the deviations are caused by the temperature, by the soldered leads or by the measurement uncertainty...

author: J-R
author_rank: Super Contributor
timestamp: August 06, 2023, 03:35:24 am
content: For the DMMCheck Plus voltage and current measurements, the probes or clips you use do not matter, for the reason I proved earlier using Ohm's law. You can put a decade resistance box in series with your DMM and crank up the resistance to see for yourself. A common resistance to encounter when using test leads/probes/etc. is going to be under 1 Ohm, typically around 0.1 Ohms if you're shorting them directly. The contact resistance would have to be very high such as 100 Ohms or more to be an issue.However, for resistance measurements, YES, the type of probe and lead you use and how you hold it makes a big difference in a 2-wire configuration, but the accepted solution is a 4-wire/Kelvin connection.Soldering on the reference invalidates the calibration, and there is just no way around that. Will all the values be different or "wrong"?? That is up for speculation and it would really require another calibration with an 8.5 digit DMM to "know" one way or another. But again the fact remains the previous calibration is no longer trustworthy.The 34450A is not a good enough DMM for analyzing the performance of the DMMCheck Plus. One year 10V range accuracy spec is 0.015% reading + 0.005% range. So 5V could display between 4.9988V and ‭5.0013V.However, I've commented before on applying too much value to published specifications, so without the calibration data we shouldn't speculate too far on the actual performance of this 34450A.But comparing the before and after measurements, and given the performance class that the 34450A is targeted for, it would be unwise to put much trust into the last digit of the display regardless.I recently received my DMMCheck Plus back from calibration:34401A: 5.000,00V34461A: 4.999,98VK2010: 4.999,995V - 4.999,997VFor verification, I also got identical readings from my PDVS2mini @ 5V.For 1mA DC, my calibration sheet states 1.0009mA and I observed:34401A: 1.000,94mA34461A: 1.000,863mAK2010: 1.000,779mAI would put more stock into the value provided by the 34461A since it has a 1mA range while the other two only have 10mA.

author: Martin72
author_rank: Super Contributor
timestamp: August 06, 2023, 08:30:38 pm
content: QuoteThe test points are "miles" away from the circuit, it cannot have been heated along with it by the very short term soldering.

author: Veteran68
author_rank: Frequent Contributor
timestamp: September 05, 2023, 02:45:44 am
content: They are now taking pre-orders for the new DMMCheckPlus units that include all options. So the enclosure, LC board, and dual frequencies are included at one fixed price now. I guess it makes it easier for them to manage fewer SKUs and also pads their margins a bit more, I'm sure.I placed an order since I'd been wanting one for awhile. I really wanted Ian's PDVS2 Mini but can't justify 2x the cost.I accepted the default dual frequencies of 100Hz and 10Khz as I wasn't really sure what else to choose. Being in the US, should I have gone with 120Hz instead of 100Hz, or is that even relevant in this scenario? That didn't occur to me until after I ordered. What are some of the reasons to choose different frequencies on a voltage standard like this? I assumed it's just for testing different AC bandwidth ranges of test equipment.

author: mwb1100
author_rank: Frequent Contributor
timestamp: September 05, 2023, 03:19:00 am
content: Quote from: KungFuJosh on July 10, 2023, 03:23:03 pmQuote from: Veteran68 on September 05, 2023, 02:45:44 amIs this the "new higher stability model"? Or is is just a step in that direction (old model but with all options included)?

author: dophuc
author_rank: Contributor
timestamp: September 05, 2023, 03:21:20 am
content: Using what I have, calibrate the Owon P4305 linear DC power supply with the Keysight 34410A to use as a source for testing handheld multimeters and lower precision devices.@10Vhttps://youtu.be/wZA3xZyQqnY@30Vhttps://youtu.be/r7gR1pGJB1A

author: Veteran68
author_rank: Frequent Contributor
timestamp: September 05, 2023, 12:41:39 pm
content: Quote from: mwb1100 on September 05, 2023, 03:19:00 amNot sure, but I hope it's the improved model. I didn't see where they actually say anything about the new model on their site. They just changed the banner to say they're now taking pre-orders, and changed the product order page to not charge extra for the add-ons (even though they still have the drop-down selection controls for them as if they're optional). I added everything including dual frequencies and the price didn't change.

author: mwb1100
author_rank: Frequent Contributor
timestamp: September 05, 2023, 03:59:14 pm
content: Quote from: Veteran68 on September 05, 2023, 12:41:39 pmThere was some period of time (around July 10 it seems) where the website's banner teased a new product in the pipeline. No details given, but@KungFuJoshgot a few via email.

author: Veteran68
author_rank: Frequent Contributor
timestamp: September 05, 2023, 04:30:41 pm
content: Quote from: mwb1100 on September 05, 2023, 03:59:14 pmYeah, the banner has been saying for some time that pre-orders for new boards would begin Sept 1. On Sept 1 I sent them a message through their contact form asking for details. I haven't got a response yet (it was a holiday weekend here in the states), then when I saw the banner had changed to now accepting orders, I placed mine. Other than all options now included there's no mention of improvements or other details.

author: Martin72
author_rank: Super Contributor
timestamp: September 05, 2023, 08:31:00 pm
content: Hi,I will send the device for a new calibration, calibration is done according to ISO*.The L/C option will also be calibrated.I was sent a sample calibration certificate, so the protocol will look like afterwards.But I still wonder, should I send it away with the soldered leads, or not - And ask instead, with which test leads / clips they have performed the calibration, to then measure with later with the same...*(Calibration according to DakkS is also possible, costs 30€ more)

author: J-R
author_rank: Super Contributor
timestamp: September 08, 2023, 01:00:51 am
content: I'm curious, did you solder the wires to the turret terminals, or remove the turrets and solder the wires to the PCB? And which ones were modified?

author: Martin72
author_rank: Super Contributor
timestamp: September 08, 2023, 05:43:57 am
content: Hi,To the turrets and then voltage/current.

author: KungFuJosh
author_rank: Super Contributor
timestamp: September 08, 2023, 06:52:36 pm
content: I got one of these AD584JH voltage refs in, and it seems to work fine. It was advertised as an AD584L, which I'm not surprised was a lie. They didn't bother to include the fake calibration either.On my SDM3055X-E I got:10.0009V07.5013V05.0004V02.5001VThat seems pretty good. The 7.5V and 10V takes a while to get up to their voltage range. After that it seems like it takes some time for the voltages to settle on their targets. Once settled, the voltage is stable.Anybody else have the same behavior with their similar reference?Right now I'm leaving the 7.5V test on to see if it gets any closer to 7.5000.7.5013 was still stable after an hour.Thanks,Josh

author: Veteran68
author_rank: Frequent Contributor
timestamp: September 08, 2023, 08:54:16 pm
content: My Agilent 34401A and SDM3065X all get to a stable voltage within a second or two. If you continue to hold the probes, they will creep up very slowly, like one count every 4-5 seconds.I just tested against the following standards consisting of 3x AD584s (2x LH and 1x KH), a LM399, and a LB02A process calibrator. The AD584LH that looks like yours (that takes the funky 15V battery) came with the fake cal sheet that everyone else has seen. The others seem to have genuine values that measure within about 1mV on both meters.

author: KungFuJosh
author_rank: Super Contributor
timestamp: September 08, 2023, 09:37:07 pm
content: Quote from: Veteran68 on September 08, 2023, 08:54:16 pmAh, weird! I was using probes clipped to the ref, and it took a minute or two to get to 10V. I turned it on without probes connected this time, then tested and it got to the voltage in a few seconds. 🙄Where did you get that purple AD584LH board from?

author: Veteran68
author_rank: Frequent Contributor
timestamp: September 08, 2023, 10:48:18 pm
content: Quote from: KungFuJosh on September 08, 2023, 09:37:07 pmhttps://www.aliexpress.us/item/3256804431053626.html

author: Veteran68
author_rank: Frequent Contributor
timestamp: September 09, 2023, 02:58:45 am
content: Quote from: Veteran68 on September 05, 2023, 12:41:39 pmSo I sent them an email today asking for any details about this "new" version and when pre-orders would ship. Russ responded this evening:"This is the Rev 6 version with all the options, meaning the new LC daughter board introduced last year (installed), dual frequencies of 100 Hz and 10 kHz, the enclosure with acrylic top and a free calibration if you send it back within two years. Shipping will commence after their 250 hour burn-in, which improves the stability of the voltage reference."So other than all options included, nothing about any design changes or improvements.

author: Martin72
author_rank: Super Contributor
timestamp: September 10, 2023, 10:14:23 pm
content: Hi,Any recommendations for really good "state of the art" test leads/clips ?Except for the set from Probemaster I have found nothing...

author: dmmguy
author_rank: Contributor
timestamp: September 11, 2023, 01:39:35 pm
content: Quote from: Veteran68 on September 08, 2023, 08:54:16 pmThey (AD584) take about 3 hours o more to reach an "acceptable stable" status, I always keep them working for more than 72 hours the very first time. I sell those boards with a cal cert measured with a Agilent/Keysight 34461A, it is not the best but may be useful for 4.5 and 5.5 digits and even for 6.5 if used at approx same cal temp.https://www.ebay.ca/itm/155763974742

author: KungFuJosh
author_rank: Super Contributor
timestamp: September 11, 2023, 01:57:18 pm
content: Quote from: Martin72 on September 10, 2023, 10:14:23 pmAlmost all of my test leads are from probemaster. Their kits/accessories are excellent.Are you looking for something they don't offer?

author: Veteran68
author_rank: Frequent Contributor
timestamp: September 11, 2023, 02:19:35 pm
content: Quote from: dmmguy on September 11, 2023, 01:39:35 pmInteresting. Are you building these boards yourself, or reselling imported boards?My understanding as the AD584's in these imported boards are mostly pulls from old equipment, so already at various stages of aging. It would be nice to have some idea of provenance at least.I do wish that particular board was built for a more practical battery, such as the A23 12V battery the purple board has. The 15V square batteries are expensive and hard to find. I bought two of the green Chinese 10F20 batteries on eBay for around $10 and one was flat within a year. The other I haven't bothered unwrapping, it may be dead too. The Exell branded ones are probably better quality but go for $20 each! So I was using it with a DC barrel plug from my bench PS, but since this board had the bogus cal sheet that just about everyone else got, it was pretty much useless for its intended purpose. My favorite among those AD584 variants is the one with the purple board, as it has a practical battery, the option to use a DC plug, and includes reference resistor measurements also. However now that I have a DMMCheckPlus rev6 on order with all options, these will be relegated to backup or consensus/sanity check purposes.

author: Veteran68
author_rank: Frequent Contributor
timestamp: September 11, 2023, 02:32:55 pm
content: Quote from: KungFuJosh on September 11, 2023, 01:57:18 pmI second the Probe Master recommendation, at least for bench use. I have 3 sets for my bench meters, including one set of the spring-loaded needle tip variety. I don't like them as much for portable DMM use, as the probes are quite a bit bulkier than the typical slim probes, though they do feel great in the hand.My next favorite have been the Brymen leads. I ordered an extra couple of sets to use in good handheld DMMs that came with shitty leads, like the super stiff TL75 PVC leads that came with the Fluke 117. I even ordered a set of TL71 leads for it which are softer but the probes still feel cheap and had inconsistent contact even after cleaning. BTW, Fluke's website still advertises the 117 as shipping with silicone leads. Lies! (sorry for the OT Fluke rant)

author: dmmguy
author_rank: Contributor
timestamp: September 11, 2023, 02:59:48 pm
content: Quote from: KungFuJosh on July 03, 2023, 03:25:54 pmI am selling them with the correct values... just in case:https://www.ebay.ca/itm/155763974742

author: mwb1100
author_rank: Frequent Contributor
timestamp: September 11, 2023, 03:43:23 pm
content: Quote from: Veteran68 on September 11, 2023, 02:32:55 pmThe Brymen silicone leads are great and a great value - 10 EUR (excl VAT) from welectron:Brymen BL21S2-T4SC Silicone Test LeadsBetter than Fluke's TL71's in my opinion.

author: Martin72
author_rank: Super Contributor
timestamp: September 11, 2023, 08:36:18 pm
content: Hi,First and foremost, I'm looking for solid taps to safely contact the "turrets" on the board.With measuring tips alone you can forget it, because you never have really safe contact.Also, these clips are no good, as I found out(Pic).If no other ideas come, I will probably buy the "big" Probemaster set from Welectron.

author: KungFuJosh
author_rank: Super Contributor
timestamp: September 12, 2023, 06:44:22 am
content: I have a couple of those sets, they're great. I don't know what welectron carries, but here you can order individual accessories directly from PM. There are certain things I needed a few extras of.

author: Shonky
author_rank: Frequent Contributor
timestamp: September 12, 2023, 08:09:22 am
content: Quote from: Veteran68 on September 11, 2023, 02:19:35 pmI also have the purple AD584LH from the same AliExpress seller link. I have two HP34401A with both unknown calibration history. One required a 5V supply electrolytic to be replaced when I got it. However both units read within about 0.0005% of each other. Compared with supplied cal (hand written not the common printout supplied with others, but no date) they both read 0.01% to 0.025% high. Not miles apart sure but noticeable having the two HPs agreeing to the last 5 counts or so out of 6 digits.

author: iMo
author_rank: Super Contributor
timestamp: September 12, 2023, 08:27:35 am
content: With your 34401A I would rather indicate diffs in ppm.. Percentages such small are hard to process..

author: Martin72
author_rank: Super Contributor
timestamp: September 13, 2023, 07:31:05 pm
content: Quote from: KungFuJosh on September 12, 2023, 06:44:22 amNow I´ve bought the "smaller" set:https://www.welectron.com/Probe-Master-8043SK-Softie-Test-Lead-Master-Kit

author: KungFuJosh
author_rank: Super Contributor
timestamp: September 14, 2023, 02:04:12 am
content: Quote from: Martin72 on September 13, 2023, 07:31:05 pmNice. I love the tiny little grabber clips in the top right corner of that photo. I use them with my DMM and scope. They're great for grabbing tiny legs on chips and stuff like that. I was even able to use them on SMD stuff like an LTC6090.

author: Martin72
author_rank: Super Contributor
timestamp: September 15, 2023, 04:43:55 pm
content: Arrived, looks very good...One of the two bigger hooks (red) is very hard to screw on the tip - wrote to welectron, maybe I get a spare.

author: Dr. Frank
author_rank: Super Contributor
timestamp: September 15, 2023, 06:25:06 pm
content: Quote from: Martin72 on September 11, 2023, 08:36:18 pmWell , the old KLEPS = Klemm - Prüf - Spitze, from the good old Hirschmann. Got still a lot of the old ones.

author: OneGeekGuy
author_rank: Regular Contributor
timestamp: September 15, 2023, 06:52:42 pm
content: That probe kit looks really good, I might order one, I have few "low" cost and they are okish, but the quality is not the best, and the price is not high.I ordered two references from Aliexpres one with the more common battery (The purple one) and the other the orange one. I would like to play a bit with them, I have Keysight 34465A on hand so I would like to measure them a bit precisely and semi long term and later on check with few multimeters I have at home just as said....for fun more than anything.

author: Martin72
author_rank: Super Contributor
timestamp: September 15, 2023, 07:23:28 pm
content: It has really good quality, everything...

author: Veteran68
author_rank: Frequent Contributor
timestamp: September 15, 2023, 08:06:19 pm
content: Yes, ProbeMasters are great, and the 8000 series "Softies" feel fantastic in the hand. A bit bulky for portable use, but great at the bench. And they're really not that expensive although I see they have gone up a bit since I last ordered a set.If you're into really fine SMD and high density QFP work, I can highly recommend theirspring loaded needle tip probes. Same body and construction as the standard 8000 series "softies" but with pogo-pin like spring loaded needle tips that you can get in four different point configurations.