DMM recommendations for my lab at home - Page 1
Forum section: electronics / beginners

author: Delillusions
author_rank: Contributor
timestamp: June 25, 2014, 06:21:01 am
content: Hi Everyone!Sorry for interrupting you, but I would like to ask your help. My current main DMM is starting to act funny from time to time, so it's almost time to get a new one and then see if I can fix her or not. S I would like if you guys could recommend me a few DMM, or DMM families which I should get or look into. I live in Europe, so most of the Fluke's are out of the question, since I have to pay extra VAT after them, which blows them out of my budget. Maybe the cheap 17b is a contender, but I would like to hear other ideas. After I heard some recommended types, then I search trough what I can get and choose one. I'm trying to not to nitpick, so the requirements will be as short as possible.Budget: ~175-200USD/130-150EUR (the 200USD/150EUR is really the absolute max.)Requirements:-uA-range-TRMS-fairly fast update speed at least for analog bar if it has one (analog bar is not part of the requirement, just the update speed)-frequency measurement at least 100MHz or higher-some input protection or to be able to upgrade it-RS-232 with some description (not absolutely required, but would be great)-9V battery (I have to change my batteries far too often if they use AA/AAAs, but but I can continue living with it if needed)-decent accuracy/resolutionThings I don't really care:-auto or manual range-Back light-internal log (with RA-232 and some description I can make it log into an SD card)Mostly I work with low energy circuits, so around 70% of my time is around 3.3V/5V. For around 20-25% is up to 20-30V, the rest is around 100-230V around the house, but for this I have other meters. I'm usually staying below 1-2A.I've already looked around and I looked at the UT-71 series. My problems with them is the accuracy (30 digits in ACV) and the input protection could be better, but there are some way to improve it at some extend. Voltcraft is almost the same as Uni-t, but it was redesigned and got better input protection, but it's harder to get.Thank you for your help in advance!P.S.: I would be happy to put this topic into the Test Equipment part, but it seemed more appropriate in here as the other is full or reviews and tear downs and equipment problems.

author: Lightages
author_rank: Unknown
timestamp: June 25, 2014, 06:48:41 am
content: Good luck finding a multimeter with >100MHz frequency measurement.My suggestion:http://www.tme.eu/en/details/bm827/portable-digital-multimeters/brymen/#and you can get the USB PC kit for it.

author: Wytnucls
author_rank: Super Contributor
timestamp: June 25, 2014, 06:59:46 am
content: Second-hand Gossen 18s or 25s should also be within your budget.http://www.ebay.de/itm/Multimeter-digital-Gossen-Metrawatt-Metrahit-18s-voll-funktionfahig-Profigerat-/251566968792?pt=Mess_Pr%C3%BCftechnik&hash=item3a928f4fd8

author: Delillusions
author_rank: Contributor
timestamp: June 25, 2014, 07:11:45 am
content: Thank you Lightages!These requirements can be changed if necessary, they were meant to give a starting point. But there are a few things I'm not willing to change. These are uA, TRMS, decent accuracy and input protection.The frequency can be changed, but I would love it to be 100MHz. I have a 100MHz analog O.scope and a Noname 7$ Chinese DMM, which is useless from every point but it can measure frequency pretty well (compared to my scope) up to 20MHz or so, but at Volt is can be 100-200d out.The UT71 fills the bill, but I have some concern about it's accuracy at ACV and the input protection.Nevertheless thank you, I will look into that Brymen.

author: XOIIO
author_rank: Super Contributor
timestamp: June 25, 2014, 07:19:55 am
content: The uni-t ut71c is actually pretty great for a bench multimeter, wouldn't be the best suited or safest for electricians work without some modifications, but it has loads of features for a great price.

author: Lightages
author_rank: Unknown
timestamp: June 25, 2014, 07:20:19 am
content: The UT71D is a good meter for the bench. It has very little input protection, slow update rate in 40,000 count mode, slow as a snail continuity, and as you said some pretty loose specs on some ranges.It comes with almost all the functions anyone could want, nice display, PC kit included and internal logging.I have a UT71E which is the same model with power measurement and it is an OK meter but mine came way out of spec and I had to adjust it.I also have a Brymen BM257, BM525, and a BM869. They are great meters and very well built.My UT71E stays in its case while my Brymens are my goto meters for almost everything.

author: Wytnucls
author_rank: Super Contributor
timestamp: June 25, 2014, 07:26:35 am
content: The latest 71D has HRC fuses and a revised PCB.Supposedly, the slow continuity was fixed on that version too, but I haven't tested it personally.The quoted worst accuracy of 30 LSD on AC volt is about 0.08% of range all the way up to 100kHz. Most meters are only accurate up to 20kHz or below (-3dB).http://www.batronix.com/shop/multimeter/multimeter-ut71d.html

author: XOIIO
author_rank: Super Contributor
timestamp: June 25, 2014, 07:28:28 am
content: Quote from: Wytnucls on June 25, 2014, 07:26:35 amdang, wish I had seen that, though the continuity isn't bad.The one I ordered has a revised PCB, I just need to order the fuse holders and convert it to HRC, I will do it for 10a, but for 500ma I may not, depends on fuse cost. I would wait till I use the four replacements I have left.

author: Delillusions
author_rank: Contributor
timestamp: June 25, 2014, 07:41:41 am
content: Fortunately or unfortunately the 71D is somewhat popular, so the shops increased it's price for more profit, so it's more expensive than the 71E or 71B. But then again accuracy and protection. It's mainly for low power, low voltage electronics. If I'm somewhat uncertain about what happens in the circuit, then first I use some cheaper DMMs to determine if it's safe for my more expensive ones or not. For DMMs I got two category. I got the one for abusing and the ones for finer, accurate measurements.

author: babysitter
author_rank: Frequent Contributor
timestamp: June 25, 2014, 07:57:57 am
content: Do you really want tomeasuremains, or whatever it is in the high range, directly or is a Indicator like a Duspol sufficient ?

author: sfiber
author_rank: Regular Contributor
timestamp: June 25, 2014, 08:30:16 am
content: I wonder,this benchtop dmm have a isolation.

author: Delillusions
author_rank: Contributor
timestamp: June 25, 2014, 08:32:31 am
content: For mains power I have other tools and equipments I can use and abuse. This one would be exclusively for ~0-30V, ~0-2A.Thank you for reminding me sfiber!Bench top DMM is a no-go. It will usually sit on my bench, but if needed I has to be able to carry it around. But that doesn't happen often.

author: Wytnucls
author_rank: Super Contributor
timestamp: June 25, 2014, 09:23:16 am
content: Quote from: Lightages on June 25, 2014, 07:20:19 amNot much on the mentioned AC voltage range. Here are the 4-5V specs compared to the best Brymen (BM869):Up to 1kHz: BM869 (0.5%+40) 71D (0.4%+30)Up to 10kHz: BM869 (0.8%+40) 71D (1.5%+30)Up to 100kHz: BM869 (4%+40) >15% of range 71D (6%+30) >10% of range

author: Creep
author_rank: Regular Contributor
timestamp: June 25, 2014, 09:47:38 am
content: I've been wondering for a while now but can't seem to find any information on this: Are the TME.eu prices with VAT included or do I have to pay the VAT on top of the indicated price?Sorry for going a little off topic.

author: Delillusions
author_rank: Contributor
timestamp: June 25, 2014, 09:50:20 am
content: In my country TME prices doesn't contain VAT, so it's actually TME prices+VAT, in my case it +27%

author: jpb
author_rank: Super Contributor
timestamp: June 25, 2014, 10:56:17 am
content: If frequency is important to you, why not buy a cheap 6 digit counter off ebay? DMMs have frequency counters that are aimed at measuring things like mains frequency and the frequency of the ACV - they are not really designed for RF frequencies so I'd go for the meter that meets your other specs and perhaps budget $50 to get a separate counter.Certainly even very expensive bench meters will not correctly measure the ACV of a 100MHz signal so there is no advantage in using a counter in a DMM if you're measuring RF signals.Edit : a quick look on the UK ebay shows you can get a 6 digit 65MHz counter from Hong Kong for around $10!http://www.ebay.co.uk/itm/0-1MHz-to-65MHz-RF-6-Digit-Blue-Led-Signal-Frequency-Counter-Cymometer-Tester-HY-/310964601707?pt=UK_Gadgets&hash=item4866ef436bthough I'd advise spending a little more to get a second hand one of perhaps 7 digits and going to your desired 100MHz+

author: Delillusions
author_rank: Contributor
timestamp: June 25, 2014, 11:51:45 am
content: I only need the ACV for a couple of kHz, not for 100MHz. The frequency measurement would be for digital signals, not for ACV. If I need more ACV bandwidth, then I have a Tektronix 2235 100MHz scope, but I don't really want to use it for every little digital frequency measurement.For that purpose a digital counter could be an alternative, but not a 10$ gadget. I only bought the 7$ DMM, so I have an extra one for abusing. It turned out it's not good even for that, just for frequency measurement. Right now I need a DMM, not just a frequency counter. I decided to upgrade gradually my lab, so I'm willing spend some money on it, that's why I'm increased my budget so I can get a DMM, which I can use and trust for years.Frequency measurement would be good, but it's optional.

author: Wytnucls
author_rank: Super Contributor
timestamp: June 25, 2014, 12:09:59 pm
content: Seems to me that you don't know what you want.One minute you need a 100MHz counter, now 2 kHz is fine. You insist on TRMS, but then you considered the Fluke 17B.You want a decent accuracy then balked at +30 digits on the AC range, which is pretty much the norm for any high-end 4 1/2 digit resolution meter.You need to nail down your true requirements before you send everybody here on a wild goose chase.

author: Delillusions
author_rank: Contributor
timestamp: June 25, 2014, 12:24:31 pm
content: Fine, I admit, that I'm an idiot.I want to measureAC VOLTAGE@2kHz. If the frequency of AC Voltage higher than 2kHz, then I can use my oscilloscope, since it's analog signal.I need the frequency measurement for digital signals, so I don't have to use always my Scope. If it could be 100MHz+, that could be good.I just looked at the UT71 series manual. It says it can measureAC VOLTAGE @ 100kHz, but with+/-6%+30daccuracy. Yet it can measurefrequency up to 400MHz.So I believe that frequency measurement and AC Voltage bandwidth are different. But I guess I was wrong.

author: iloveelectronics
author_rank: Frequent Contributor
timestamp: June 25, 2014, 12:44:24 pm
content: There are usually 2 different frequency specs for a DMM. One is the line level frequency, or the AC voltage bandwidth, the other is the logic level frequency, which is what you need for your digital signals.

author: madshaman
author_rank: Frequent Contributor
timestamp: June 25, 2014, 05:01:46 pm
content: I really think you should consider getting a separate frequency counter as others have suggested.It opens up more choices for your replacement DMM, particularly if you want a bench meter.For used bench meters, I'm partial to Keithley, particularly the 196, but there are better modern meters for not much more I'd think. My Keithley 2015THD cost me about the same as my 196 believe it or not (about $4-500 CAD iirc).Honestly, I look for big bright numbers (I hate non-lit LCD displays) and a meter already in calibration with a decent reputation (Keithley's cap problems not-withstanding).I also like a fast update rate and many digits of accuracy, but I wouldn't recommend more than 5.5 if you don't think you'd need it.Honestly, look for the meter *you* want, and maybe run it past the forum to see if it's s**t.I do think your requirements of a built-in frequency counter make it tougher. You'd probably more easily find a used Tek or HP scope with a built-in DMM and frequency counter that meets your requirements. Want to get an analog scope for free with your meter?

author: Delillusions
author_rank: Contributor
timestamp: June 25, 2014, 05:42:01 pm
content: Thanks madshaman, but I already have a Tektronix 2235 scope, so I can use it for frequency measurement up to 100MHz, but it's not a built in meter. I have to read it.Then again I already stated, that I don't want a bench top DMM. It will usually sit on my bench, but from time-to-time I have to carry it with me and use it outside my "lab".I also sated earlier in my post, that it would be good if it has a "Digital Signal Frequency Counter" (so everyone knows what I mean) with 100MHz+, but it's not the most important part, so it can be changed or left out.For resolution I want more that 2000 count.I already searched the forum for the DMMs I found and I know what Wytnucls thinks about some of them. I didn't gave you exact bands and names, so I can get recommendations for DMM families and maybe I can find a new one I didn't see before.Wytnucls!You're right, the Fluke 17B is not a TRMS, and I was wrong. Now I correct myself. Fluke's are out of the question event the used ones.

author: Lightages
author_rank: Unknown
timestamp: June 25, 2014, 05:57:29 pm
content: If what Wytnucls says about the newer UT71Ds is true, ie faster continuity, better input protection, then get that. It is as close as you will get to your wish list and price. But note that he is not stating he is sure. If you want known quality then the Brymen BM827 is in your price range. Or maybe a BM257 and the PC kit and I believe the total price with taxes and all will still be below your $200 limit. The UT71D is a better bench electronics meter though than the BM257.

author: Delillusions
author_rank: Contributor
timestamp: June 25, 2014, 06:09:35 pm
content: Unfortunately the UT71D in my country blows my budget (fairly popular so they selling it with quite some profit) and getting it from outside of my country could easily blow my budget. But I can get the 71E in my country while staying in my budget.Wytnucls! You own a 71D and know quite many thing about them. I have a question about them. In 40.000 count mode the 71D send 1 data packet to the PC trough RS-232. If you put the 71D in 4.000 count it increases, but how much? How many time will it send data to the PC in 1 second?

author: Lightages
author_rank: Unknown
timestamp: June 25, 2014, 06:17:13 pm
content: With my UT71E, the update rate goes to mostly 10 updates per second when switched into 4,000 count mode if I remember correctly.You can get UT71Ds on ebay for less than $190 shipped and including your 27% taxes when it hits your country. I don't know if there are other import costs where you live.

author: Delillusions
author_rank: Contributor
timestamp: June 25, 2014, 06:56:15 pm
content: Thank you Lightages! I suspected that, but it's better to ask.Correct me if I'm wrong but there are two main difference between the D and E model.The E has a built in Power meter, which can measure power up to 2500W, but it can measure power continuously for ~1100W. Abow that it can only do it for 5sec, otherwise it will be fried. It's because the 71 series can measure current continuously up to 5A. Above 5A you can only mesure it for 5sec and then you have to wait a few minutes.The D model doesn't have the power mode, but it has a very much larger internal log capacity. Which is useless, since I can make a device, that reads the measured data from the IR LED and logs it into an SD card. It became an almost infinite logger, it's just that I can't read it back with the DMM.Knowing the leaders of my country and the Duty Office they will find out something to make me pay something more, but besides that if I can get it inside my country, the any warranty issues could be handled more easily, but that is just a small issue.I've also read, that some Uni-t DMMs continuity test isn't the best, but in some cases it's because the test leads have some kind of coating on them. Properly cleaning them or using another another trustworty lead can make it better. It won't make it faster, but I could make it better.

author: Lightages
author_rank: Unknown
timestamp: June 25, 2014, 08:56:46 pm
content: With all your concerns, just get the BM827. I can assure you it is high quality, fast, and safely built.

author: madshaman
author_rank: Frequent Contributor
timestamp: June 26, 2014, 01:48:12 pm
content: Sorry, I misread your original post. If you want a handheld, I can also highly recommend Brymen, I own two 867s, and I don't think you'll find better bang for the buck outside that brand.You *might* have trouble finding someone to sell you one. I bought mine from TME in Poland, shipping was something like $20 to Canada and you can look at their site for prices; I have no idea if they sell the particular Brymen meter you want.[edit: typos]

author: madshaman
author_rank: Frequent Contributor
timestamp: June 26, 2014, 01:50:26 pm
content: http://www.tme.eu/en/details/bm827/portable-digital-multimeters/brymen/

author: Delillusions
author_rank: Contributor
timestamp: June 26, 2014, 03:11:52 pm
content: Which one do you recommend from these two Brymens?BM-257BM-857AI saw Dave's teardown video.

author: Lightages
author_rank: Unknown
timestamp: June 26, 2014, 07:06:22 pm
content: The BM857A is a much more capable meter than the BM257. The one thing it lacks is temperature measurement. If that is not important to you then get the BM857A. If you want temperature, the BM257 has it but its TRMS measurement is AC only as is the BM827.IMHO, get the BM857A. You can always buy a cheap temperature meter later.