Author Topic: Help with new DMM  (Read 18922 times)

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Offline zorthgo

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Help with new DMM
« on: July 08, 2013, 09:07:39 pm »
Hi guys, recently it was brought to my attention that I can't keep relying on my little $20 Radio Shack DMM, and I need to shell out the money for a proper DMM. At my level of electronics involvement the only things I've been using the DMM for is to measure Volts, Amps, Ohms, and Capacitance. I know DMMs are used for more advanced things but I haven't reached there yet. I would like to get a DMM that I won't surpass it's abilities pretty quickly, but also that it isn't super overkill. I have 3 in mind but I don't quite know how to choose (or if there are better options for a beginner like me). Below are the DMMs I was looking at:


Manufacture                    Model               Price         Resolution

Rigol                                   DM3058           $695           240,000

B&K PRECISION                  5491B              $409           50,000

Agilent                                U3402A            $641           120,000       


Please let me know what you think. Also if you  have any alternatives!
« Last Edit: July 08, 2013, 09:11:31 pm by zorthgo »
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Offline zorthgo

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Re: Help with new DMM
« Reply #1 on: July 08, 2013, 09:15:27 pm »
Also, the

Rigol         DM3058E           $449            240,000

Frankly I don't know the difference between the DM3058E and the DM3058.
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Offline Lightages

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Re: Help with new DMM
« Reply #2 on: July 08, 2013, 09:21:27 pm »
Yes, overkill unless you really need a bench meter. I would suggest you read the following:
https://www.eevblog.com/forum/reviews/a-list-of-recommended-multimeters/
https://www.eevblog.com/forum/testgear/a-list-of-multimeters-that-do-not-appear-to-meet-their-claimed-safety-specs/

But in general I would recommend an Agilent U1272A, or a Brymen BM869 or BM525 or BM257, or Fluke 87V. These would be the best bets in a good higher end handheld meter. If you can get one I would seriously consider the BM869 as it really is the best bang for the buck. It can be purchased from www.tme.eu for around $240 plus shipping which is around $30 I think by UPS. You can't go wrong with the Fluke or Agilent but they cost much more.

Is there a specific reason you are only looking at bench meters?
 

Offline IanB

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Re: Help with new DMM
« Reply #3 on: July 08, 2013, 09:43:43 pm »
Hi guys, recently it was brought to my attention that I can't keep relying on my little $20 Radio Shack DMM

I am more than happy to use my $50 Radio Shack DMM on my electronics bench (the model 22-812). I have two of them.

If you are just starting out and you don't go sticking the probes in a mains socket, then you really don't need to spend more than $50 on a DMM, and even $25 would probably do fine. Just like if you were starting out at tennis you wouldn't spend $300 on a tennis racket.
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Offline c4757p

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Re: Help with new DMM
« Reply #4 on: July 08, 2013, 09:49:41 pm »
:wtf:

Extech EX-430, $70
Extech EX-330, $53
B&K Precision 2704C, $56

Many others...

I've seen some pretty shameful crap for $20 at RadioShack, but that doesn't mean you need to start looking at 20x that price and above for something good!

BTW, I own the B&K 2712 (twice the cost), and my only complaint about it is the nonstandard input impedance (seriously, what the hell is 2.3 Meg?). It's an excellent meter. I suspect the 2704C is similar.
« Last Edit: July 08, 2013, 09:59:05 pm by c4757p »
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Offline madshaman

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Help with new DMM
« Reply #5 on: July 08, 2013, 10:07:47 pm »
All I'd say is, know what additional features you'll be shelling out money for and if you'll use those features.

If you have the need for a 250,000 count meter, then you'll know it.

May I ask what your radio shack meter is unable to do for you in the here and now or in the near future?

Also, if you *do* need a ridculously accurate bench meter, consider a used HP3457 or something.  They are *exactly* as good as a new meter (could even argue "better" in some cases).
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Offline zorthgo

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Re: Help with new DMM
« Reply #6 on: July 08, 2013, 10:33:50 pm »
@madshaman, basically the only thing that my little DMM doesn't do (that I am aware of) is that it doesn't have the ability to measure capacitance. I also, don't really trust it's voltage measurements (psychologically I trust the bench DMM better). @IanB, I not really planning on probing any main! ;)  I am actually going to use it for low power analog/digital circuits (such as microprocessors, transistors, opamps, sensors, etc). @Lightages, I guess I don't actually need a bench DMM. It's just that at school all out DMMs were bench, so I feel more comfortable with them.. I guess! 
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Offline c4757p

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Re: Help with new DMM
« Reply #7 on: July 08, 2013, 10:44:25 pm »
You can easily find used bench DMMs for a good price that are often still accurate. I buy, sell and repair used DMMs and scopes quite frequently, and with both types of instrument, I very rarely see anything that still works and isn't still spot-on. After a few cal cycles, it's pretty much done drifting around. It's only the broken stuff that often has to be adjusted after parts are replaced. If you really like bench meters, I suggest that. The old Flukes are great, just watch out for failing LCDs.
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Offline c4757p

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Re: Help with new DMM
« Reply #8 on: July 08, 2013, 10:48:28 pm »
@madshaman, basically the only thing that my little DMM doesn't do (that I am aware of) is that it doesn't have the ability to measure capacitance. I also, don't really trust it's voltage measurements (psychologically I trust the bench DMM better).

Bah.... the last time I measured capacitance on a DMM was... hmm... well, I think I was testing a meter to see if it worked right! Caps rarely fail by changing in capacitance. 99% of the time, its value is on the label.

As for voltage accuracy, in my experience the cheap ones are a gamble. Some are very accurate and some are not. I've seen more than one that was clearly adjusted incorrectly in the factory. Many people are just fine with using a $20 RadioShack meter, I am not.

You can get higher accuracy specs in a bench DMM, but a decent handheld will be more than enough for almost all uses. (Still, as I mentioned above, I do understand the desire to have one for other purposes.)
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Offline IanB

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Re: Help with new DMM
« Reply #9 on: July 08, 2013, 10:55:22 pm »
I also, don't really trust it's voltage measurements

Then learn how to verify them using some standard resources. Get two different $25 meters and compare them. How close are they? The difference between their readings will give you an estimate of the accuracy of either.

Test a brand new alkaline AA cell (should be about 1.6 V). Test a new 9 V alkaline (should be about 9.6 V). Test a new 9 V heavy duty cell (should be about 10.0 V). Measure the forward voltage drop on some known LEDs (the Vf will often be given on the data sheet or packaging).

Learn to "feel" what voltages should be what, don't just put blind faith in instruments.

Also remember that a DMM is a luxury not known to hobbyists of the past. A few decades ago we made do with analog meters and we got on fine with those.

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Offline IanB

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Re: Help with new DMM
« Reply #10 on: July 08, 2013, 10:59:23 pm »
I've seen more than one that was clearly adjusted incorrectly in the factory.

Most of my inexpensive meters have been that way, but on the plus side I learned how to adjust them to my satisfaction. Mostly they seem quite stable and they don't appear to drift after I have adjusted them.

On the other hand, if your meter is 0.5% out from the factory are any of your circuits going to fail to work?
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Offline cthree

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Re: Help with new DMM
« Reply #11 on: July 08, 2013, 11:30:10 pm »
Damn. You can get a used Agilent 5 1/2 digit bench meter for under $100. A Fluke 87-3 for about the same price. Don't spend more than $100, you won't get your moneys worth. Buy two $100 meters so you can measure amps and volts simultaneously and cross check for confidence.

http://www.ebay.com/itm/Hewlett-Packard-HP-Agilent-3478A-3478-Multimeter-4-wire-Ohm-Measurement-/221249524148?pt=LH_DefaultDomain_0&hash=item33837fd1b4

http://www.ebay.com/itm/HP-Hewlett-Packard-Agilent-3468B-Multimeter-106-126V-/280901319461?pt=LH_DefaultDomain_0&hash=item416705fb25

I bought two good condition HP3468B meters for $70 and $80 each. Watch for them, don't pay the screw me now prices. You can buy for half at auction. All you need for these are some shielded banana jack adapters, these use standard 4mm banana jacks so won't accept dmm probes without adapters.

http://www.ebay.com/itm/Fluke-Meter-87-III-/221248994561?pt=LH_DefaultDomain_0&hash=item338377bd01

http://www.ebay.com/itm/FLUKE-87-III-TRUE-RMS-MULTIMETER-WITH-CASE-VERY-GOOD-CONDITION-/141009730905?pt=LH_DefaultDomain_0&hash=item20d4d5bd59&vxp=mtr

http://www.ebay.com/itm/FLUKE-87-III-Excellent-Condition-TRUE-RMS-INDUSTRIAL-MULTIMETER-/111113594830?pt=LH_DefaultDomain_0&hash=item19dee2e7ce

Difference between 87-3 and 87-v is thermocouple temperature support. Lifetime warrant, waterproof, indestructible. Don't let dirt throw you. These meters are the kind of kit that is used in dirty places. Clean it. You'll use it for life.
 

Offline Lightages

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Re: Help with new DMM
« Reply #12 on: July 08, 2013, 11:38:15 pm »
Based on what you have said so far zorthgo, I Think you should consider the Brymen BM869. It will do everything you need, and still be safe for high energy circuits in the future. If you prefer to spend less, then the BM257 or the Amprobe AM-270 which is available in the US directly from www.testequipmentdepot.com for around $90 plus shipping. The only bad thing on AM-270 meter is its back light.
 

Offline madshaman

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Help with new DMM
« Reply #13 on: July 09, 2013, 12:54:03 am »
If capacitance it what you need, you might also consider an LCR meter.

I do on occasion end up measuring capacitance, it *is* useful, but only you know if it's useful to you.

I second the recommendation of the Brymens and another choice is the BM867, compare to the 869 and you might find the extra money for the 869 isn't worth it for you.
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Offline zorthgo

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Re: Help with new DMM
« Reply #14 on: July 09, 2013, 01:23:32 am »
@madshaman & Lightages, looks like the BM869 is in the lead with two votes!  ;)


@cthree, I thought about looking at ebay for a used one. But since I am a newb still, I would rather get something new that I am sure is calibrated and working correctly. Because I would not be able to spot a faulty meter and it would only confuse me when doing my studies. But thanks for the suggestion! ;)
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Offline c4757p

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Re: Help with new DMM
« Reply #15 on: July 09, 2013, 01:39:15 am »
On the other hand, if your meter is 0.5% out from the factory are any of your circuits going to fail to work?

No, of course not, but the more precise it is, the more you can do. Many circuits could be successfully built with a meter out by 20%. OTOH, one of my biggest hobby interest areas is test and measurement, and I like to build things to a decent level of accuracy because 1) I'm a perfectionist, and 2) I want to be able to rely on the things I've built just as much as the things I've bought.

I also repair a lot of test equipment for resale, and I like to be able to get it within its specs. I personally consider it false advertising to sell something as "working" if it doesn't meet its spec sheet.

Obviously, though, you only need as much accuracy as (or slightly more than) the circuits you plan to build or work with. The problem I have with these cheap multimeters is that they often do not meet their spec, so a beginner with an interest in measurement accuracy could easily be misled by reading the spec sheet and making the somewhat reasonable assumption that the brand-new meter would match it.
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Offline Fsck

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Re: Help with new DMM
« Reply #16 on: July 09, 2013, 02:06:26 am »
If capacitance it what you need, you might also consider an LCR meter.

I do on occasion end up measuring capacitance, it *is* useful, but only you know if it's useful to you.

I second the recommendation of the Brymens and another choice is the BM867, compare to the 869 and you might find the extra money for the 869 isn't worth it for you.
Ditto. BM869 is an excellent value. Though the BM867 is actually an even better value if you don't need the additional features of the 869.
I use my 869 the most out of all my meters, especially when I don't want to wait for my 3457 to stabilize completely.
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Offline cthree

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Re: Help with new DMM
« Reply #17 on: July 09, 2013, 02:28:11 am »
Fair choice, but still, don't spend too much. The recommendation about sounds reasonable and they are both knowledgeable users. I'm sure you would be happy with it. Still, buy two meters. I use two all the time.
 

Offline Fsck

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Re: Help with new DMM
« Reply #18 on: July 09, 2013, 02:44:45 am »
If he can do the 400-700 for those bench dmms, he can grab an 869 and another meter (like an 867, possible 869 depending on shipping and such)
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Offline zorthgo

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Re: Help with new DMM
« Reply #19 on: July 09, 2013, 03:08:26 am »
Good Idea Fsck, for the second DMM I think I am getting the EXTECH EX430 as c4757p suggested!  :-DMM


Thanks for the help guys! Much appreciated!
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Offline Rick Law

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Re: Help with new DMM
« Reply #20 on: July 09, 2013, 03:43:37 am »
Good Idea Fsck, for the second DMM I think I am getting the EXTECH EX430 as c4757p suggested!  :-DMM


Thanks for the help guys! Much appreciated!

May be get two of equal quality?

Let me explain my frustration and see if that annoying feeling may get you too.

What I found most annoying with multiple DMM is:  I am always temped and switch to my better DMM to "there" and see what the reading really is "there".  So it is like as if I have just one.

I have 4, a cheap DT830B (2000 count), a cheap 2000 count Radio Shack, a 4000 count Radio Shack, and a 22000 count UT61E.

I rarely swap out the DT830B because I calibrate it to be +-1 digit from my UT61E for the ranges I use.  The two RShack are not calibratable.  I know from experience both are +- 3 to 5 mV (and +- 3 to 5 count whichever is larger).  So, when I have a four-meter arrangement such as: In-Volt, In-mA, out-Volt, out-mA.  I often end up thinking: what really is the In-Volt exactly, let me switch my 22000 count meter to there and put the RShack here.  Wait, what is really is the current, let me switch my 22000 count meter there and put the RS there.  So I am swapping back and forth as if I have only one DMM.  Well, actually as if I have just two.  After I calibrated the DT830B, it tracks the UT61E well and I feel I get the "right reading" even while it has only 2000 count.  So what really bugs me is not the accuracy or precision but the inconsistency when the two RS are not consistent with itself, and not consistent with the other meters.  Small delta at merely +- 3-5 counts but it bugs me enough that I don't feel I have a reading.

A bit silly to be bothered by consistency so much, I admit.
 

Offline IanB

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Re: Help with new DMM
« Reply #21 on: July 09, 2013, 04:12:33 am »
I like to build things to a decent level of accuracy because 1) I'm a perfectionist, and 2) I want to be able to rely on the things I've built just as much as the things I've bought.

As a perfectionist, I also like to see things looking right:



But to be reasonable, after the fourth digit or so I can accept a small amount of deviation  ;D
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Offline zorthgo

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Re: Help with new DMM
« Reply #22 on: July 09, 2013, 04:22:06 am »
@IanB, now I get why you didn't mind you Radio Shack DMMs! After seeing the picture you will understand why I need a real DMM! ;)
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Offline zorthgo

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Re: Help with new DMM
« Reply #23 on: July 09, 2013, 04:24:54 am »
@IanB, Question... Did you make your own banana plug cables for you power supply? Where did you get the banana end clips? Do they work as well as the store bought ones? I need some cables fast would be cool to make them! ;)
« Last Edit: July 09, 2013, 04:35:34 am by zorthgo »
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Offline c4757p

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Re: Help with new DMM
« Reply #24 on: July 09, 2013, 04:26:07 am »
That one might not be too bad, actually, just don't use it on high energy circuits. (A general rule is this: If you can't afford a proper name-brand electrician's meter to work on high energy circuits, you can't afford the hospital bill when you screw up either. Stay away. - Might not be applicable in countries with real health care.) Unless I'm mistaken, from that picture it appears to be one of those little "pocket" meters? They're kind of cool, even "Hooray for Fluke" Dave said he recommends one, and from what I've seen they're usually not total pieces of shit.
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