Voltage Reference Modules - Page 1
Forum section: electronics / beginners

author: rorymax
author_rank: Contributor
timestamp: October 07, 2021, 08:30:14 pm
content: Hi, I am an absolute neophyte, presently I am following online tutorials for basic Digital Multi Meter operations.I have a few budget range DMM's including one ac\dc clamp meter, for one thing I would like to establish the voltage reading accuracy of my DMM's.I am thinking that the devices in the following link (see below) might be what I need, I see that there are two options (green and yellow) but I don't know which one is right for me, nor do I understand what powers these devices.Can any of you folks give me some guidance?Any other advice or suggestions gratefully accepted.Thanks.https://www.ebay.co.uk/itm/123779059216?var=424434054868

author: bob91343
author_rank: Super Contributor
timestamp: October 07, 2021, 08:56:20 pm
content: https://xdevs.com/doc/Taobao/AD584_VREF/pdf/AD584_b.pdfThe data sheet should answer most of your questions. The unit draws 1 mA and is very insensitive to supply voltage variagion, so nearly any power supply should work.

author: RoGeorge
author_rank: Super Contributor
timestamp: October 08, 2021, 12:55:38 am
content: Quote from: rorymax on October 07, 2021, 08:30:14 pmTo find that you'll need to read the technical specifications of each DMM's. The accuracy is written in the specs.Most of the DMMs, including the cheap ones, have very good accuracy on DC and are usually well calibrated from the factory, using better voltage references than the one you want to buy.The question is, does it really matter for your work if it's 2.382V vs 2.389V? And if you see, let's say a deviation of 5mV from the expected 2500mV, how would you know if that error is from the reference or from the DMM?You can check the relative error by simply measuring the same battery, or maybe by putting all the DMM in parallel to measure the same battery. What did they measure if you do that?I don't know which one would be better, the price looks too cheap to be trustworthy, but it might also be good enough for what you need, IDK. See what others are saying about such a module:https://www.eevblog.com/forum/metrology/are-cheap-ad584-units-worth-it/

author: Terry Bites
author_rank: Super Contributor
timestamp: October 08, 2021, 01:58:54 pm
content: The referrence needs to have very low drift and precision and the initial accuracy. So does the price. The ADR01BRZ is great vfm with specs good enough for a beginners lab.https://www.analog.com/media/en/technical-documentation/data-sheets/ADR01_02_03_06.pdfThe accuracy of a DVM is only crucial for precsion work. However... lots of cheap DMMs have crap linearity and thermal stability. You can calibrate it for a particular voltage at a particular temperature and find its out of whack a few hours later. Invest a decent on brand DMM.

author: wizard69
author_rank: Super Contributor
timestamp: October 10, 2021, 06:10:57 pm
content: Having a voltage reference can be worthwhile but I'm not too sure I'd trust what is linked. It is cheap, looks cheap and isn't housed in a container. A decent voltage reference chip can cost many more dollars than that thing. Beyond that how do you intend to calibrate it?Before you do any purchase I'd suggest reading up with respect to some of the threads in the metrology sub forum. People have come up with a number of useful reference designs for exactly what you want and there may be threads on commercial units. There may even be boards available. We are not talking dirt cheap like this board but rather robust designs.Now all of that being said I do want to carefully say it might be a bit early in the process to worry about purchasing one of these references. For a quick check of meter operation you can get by with a reasonably precise resistor and a known good battery. Sure this isn't precision but they should be able to help you verify that a meter is working to some level. In the end I look at it as wasting money early on in your coming up to speed with electronics. You would be far better off with two DMM, one being notably better than the other. Beyond that there are other instruments to invest in.On the flip side it can be very useful in industry to have references and precision voltage sources. I wouldn't suggest wasting money on them right now. At work I put a precision 100ohm resistor in a little box to have quickly available for quick peace of mind tests on RTD circuits, I wouldn't even recommend that for a start up lab. Which brings up one other point, anything that is suppose to be precise and reference quality should be in a box of some sort. You really want a precision source to be protected.So personally this is not a route I'd take. It might work for you but in the end it may just lead to confusion or not trusting your meter.

author: rorymax
author_rank: Contributor
timestamp: October 10, 2021, 08:48:30 pm
content: You are of course correct in everything you say, and I accept my rushed indulgences are inept and poor dececisions.I am an admitted 'dumpling' to al of this, a total newbie, I am caught up in the subject, jumping the gun by a long shot (so to speak).I am already smitten by the 'must have gizmo' bug, my bad.Please forgive my dumb enthusiasm, I will refrain from further uninformed purchases.Your reply (and the others) are really helpful, if I can make an excuse it is that the subject of basic electronics has caught my attention, and I do want to learn so much more (albeit putting the cart before the horse, LOL).I will endeavour to research my proposed future requirements with a more discerning approach, for that I can thank all of the responders, hope you understand, and I am happy to learn from my mistakes.Keep me in line please, much appreciated,Best,Rory

author: radiolistener
author_rank: Super Contributor
timestamp: October 11, 2021, 01:23:08 am
content: Quote from: rorymax on October 07, 2021, 08:30:14 pmThese Chinese devices using fake or remarked voltage reference IC, so it cannot provide precise enough voltage output.If you're lucky you can get real AD584J remarked as AD584K.But if you're not lucky, you will get fake AD584 which cannot provide precise voltage.The bad thing is that you cannot even understand what you got. Because Chinese guys using very good technology for remarking or create fake chips.It's better to buy original voltage reference IC on mouser or digikey and build your own voltage reference. AD584 is outdated VREF and has pretty bad performance, so using more modern VREF IC you can get much better result. But don't buy it on ebay/aliexpress, because you will get a fake.I'm using hand made VREF build on originalADR290E. It is obsolete now, but works good enough.

author: ledtester
author_rank: Super Contributor
timestamp: October 11, 2021, 01:31:05 am
content: I have one of those and it's a fine little gadget to have for $6 as long as you understand what its limitations are and the limitations of the meters you use with it.Some of these offerings come with measurements from a high precision multimeter. Can you trust those measurements? Well, that's a whole other story. Would I trust them to the 10uV precision that they are given at? Probably not, but I don't have any problems trusting them to the 1 millivolt level which is adequate for testing budget multimeters.An inexpensive device which can be rather useful for other things is the "4-20mA 0-10V voltage calibrators" you can find on aliexpress and ebay. They range from $20 on up.If you are really serious about calibrating your multimeters, have a look at:- DMMCheck Plus --https://dmmcheckplus.com/- PDVS2mini --https://www.ianjohnston.com/index.php/onlineshop/handheld-precision-digital-voltage-source-2-mini-detailYou can find reviews/discussions of both of these on the forum and on youtube.

author: radiolistener
author_rank: Super Contributor
timestamp: October 11, 2021, 01:38:36 am
content: Quote from: ledtester on October 11, 2021, 01:31:05 amYou cannot trust them to 1 mV, because even original AD584K cannot provide such precision. But Chinese guys selling remarked AD584 with worse specification from old equipment or just a fake AD584 produced in someone's basement, their spec don't meets even original AD584J, which has ±30 mV. This is not AD584, it just have a metal case which looks as AD584, but there is some cheap counterfeit insideAnd these "calibration paper" which come with Chinese AD584 is also fake (this is already proven by many peoples). Because measurement shows completely different values.They just wrote random values or print the same value for all IC.I suspect that any Chinese DM830 is more precise than these fake voltage references with counterfeit AD584

author: wizard69
author_rank: Super Contributor
timestamp: October 13, 2021, 02:31:03 pm
content: Quote from: rorymax on October 10, 2021, 08:48:30 pmBelieve me I'm one of those people with the gizmo and tool bug, so it is easy to see people with the same condition. I just see this item as a poor value all around.So don't stop buying, a nice collection of tools and instruments means you can pursue many interests.I might add, sometimes you have to make choices about "quality". For example Harbor Freight sells a lot of junk and a few items well worth the price. Sometime it is a good idea to shop there but you have to buy wisely. In the same token, buy wisely when purchasing new stuff for your bench, no matter whom you buy from.

author: wizard69
author_rank: Super Contributor
timestamp: October 13, 2021, 02:46:11 pm
content: DMMCheckPlus, is not a bad value once someone gets to the point where they have a decent lab setup. For most people staring to configure a test bench I still think buying more than one DMM is a better investment.Quote from: ledtester on October 11, 2021, 01:31:05 am