What is the deal with multimeters?

[Guitarfreak]

I most likely need one for the work I am doing, or I will need one in the future.  I notice that they range from $5 to upwards of $100.  If you could choose, what kind would you get and why?

[Top Top]

I guess it depends on what you are planning on doing. I have a $15 radio shack one that serves me fine for getting voltages and testing resistance and continuity...

People with more expensive ones will hopefully educate us on the finer points of multimeters 

[Nasse]

I have read that some cheap ones might have safety problems when measuring high voltages.

But one thing I learned in the real life, I had a change to work with real old professionals. They did not use expensive and fine meter when we got our car and toolboxes packed for some out of base station work

[Mark Hammer]

$25 can get you a lot of multimeter these days.  ideally, you want one that:

is autoranging
is 4-1/2 digits not 3-1/2
has capacitance measurement
can test diodes and transistor hfe

For the kind of stuff we do here, it's good if it can measure resistances up in the 20M range, capacitances between 2pf and 100uf, and AC voltages down to a couple of millivolts.

Be advised that plenty of meters can have those specs, and vary in their: accuracy, current draw.

It's also good if it has an audible indicator, so you can use it for continuity testing without having to look at the display.

[Guitarfreak]

Wow, so much good info, thanks a lot guys.  According to all the specs listed above, would you prefer analog or digital?

[JKowalski]

Wow, so much good info, thanks a lot guys.  According to all the specs listed above, would you prefer analog or digital?

Most of the specs listed above are typically only found in digital multimeters.

I don't see why anyone would buy an analog multimeter nowadays...

[aron]

Digital by far. The FAQ has info on this and much more.

[pjwhite]

I have 4 digital multimeters.  One basic handheld that I have owned for many years and is a good workhorse for voltage and resistance measurements.  I have another small one that I won as a prize for answering a survey or something.  A third handheld I bought for its capability to measure capacitance, which is a pretty neat feature.  My fourth meter is an old 5+ digit HP bench meter I bought so that I would have a good accurate way to measure voltage and make 4-wire resistance measurements (useful for super-matching resistors).
The handheld meters are scattered about the house, so there is always one near at hand. 

By the way, I prefer to use a simple analog "beeper" continuity tester, rather than the ones built into the handheld meters.  My homemade analog beeper has an instant response time and you can judge circuit resistance in the 0-10 ohm range by the beep frequency -- much more useful than the sometimes misleading digital meter beep/no beep.  And the digital meter has to do an A/D measurement before you get the beep; sometimes waiting a quarter or half second for a reading is too long to wait!

[amptramp]

One thing to watch for is the maximum resistance the multimeter can measure.  On the cheap units it is 2 megohms.  Better units measure 20 or 30 megohms.  If you have a need for higher resistance measurements (which are used in some tube amplifiers and effects units), go for the more capable unit.

[Guitarfreak]

Thanks again for all the advice.  I suppose I should order one while the idea is fresh in my mind.  What do you honestly think of these models?

http://www.mouser.com/ProductDetail/AMPROBE/PM51A/?qs=sGAEpiMZZMtNaRJxj63fb8zjbksnPpSE4azQHr4dqQU%3d
http://www.mouser.com/ProductDetail/AMPROBE/AM-240/?qs=sGAEpiMZZMtNaRJxj63fb7kGpGSF%2fak2vHcByt%252begYA%3d
http://www.mouser.com/ProductDetail/BK-Precision/2703C/?qs=sGAEpiMZZMtNaRJxj63fb79xgNblw1hARTU9OypC4Nw%3d

[petemoore]

  A batch of the cheepie type.
  I think I get good mileage with 'em, and anything could happen, even to the finest the trade offers.
  At this rate, duplicity gets reliability merits, a comparator or a spare-o-meter is a good feature of duplicity in three's. One up for repairs [the battery or leads mostly], one just blank or 'blinky' [contact failure], and a couple that work like new, when by the laws of physics, it can't be right, I'll get the second opinion by grabbing the other meter to confirm the thing that can't be, like a low meter reference battery.
  I sometimes wish I had a more accurate meter, so I could know more exactly by unit instead of working percentages [even if the meter says 9 is 8, hopefully 1/2v is close to half of the supply voltage it read], mostly it doesn't seem to be critical, compared to the resistor values, seems to be very accurate, in the case of 1/2 voltage divider, I can measure the resistors for = values.
  The features Mark mentioned would of course be nicer for use. 

[boogietube]

I have two meters:

http://cgi.ebay.com/DT-9205A-Large-LCD-Display-Digital-Multimeter_W0QQitemZ380192366845QQcmdZViewItemQQptZBI_Electrical_Equipment_Tools?hash=item58853b20fd

and this one:

http://cgi.ebay.com/3-1-2-LCD-large-capacitance-Capacitor-Meter-0-1pF-20mF_W0QQitemZ250562771667QQcmdZViewItemQQptZLH_DefaultDomain_0?hash=item3a56b47ad3

The first one does measure capacitance, but the second one has better resolution and I use it for caps/inductors.
For about 60$ you have a great set of measurement tools.

[DougH]

I've had a Radio Shack DVM for ten years and it still works fine. If I was doing electronics as a business I would spring for a Fluke. But for light household/hobby duty the Radio Shack units work fine.

[Pakaloabob]

Just my $.02:
I am pretty new to effects building, but I have learned quickly that a multimeter is essential.
I have found that measuring resistance and voltage in all my circuits has been helpful. However, it would be nice to have the options to read capacitance as well.
I am curious how useful Hfe measurement from a multimeter is. This article by RG Keen:http://geofex.com/Article_Folders/fuzzface/fftech.htm, in the section about Picking transistors for FF Clones, gives a method to calculate Hfe from voltage readings and also gives reasons that direct measurement from a DMM may be inaccurate.
But yeah, Resistance and Voltage essential, capacitance would be nice.

Edit: I forgot to say that I have a fairly cheap RS meter that does fine.

[jimmybjj]

can anyone point me in the direction of a multimeter that has hese attributes? I cannot find a meter that has both hfe and autoranging.

$25 can get you a lot of multimeter these days.  ideally, you want one that:

is autoranging
is 4-1/2 digits not 3-1/2
has capacitance measurement
can test diodes and transistor hfe

For the kind of stuff we do here, it's good if it can measure resistances up in the 20M range, capacitances between 2pf and 100uf, and AC voltages down to a couple of millivolts.

Be advised that plenty of meters can have those specs, and vary in their: accuracy, current draw.

It's also good if it has an audible indicator, so you can use it for continuity testing without having to look at the display.

[petemoore]

  Hfe is nice, for GE's for effects see GEO tech of FF and subtract the leakage.
  Just for finding pinout and suitability of SI's the Hfe meter is the schnitz.
  For hugeass resistors, it hasn't mattered as long as they're either big or huge...when the range is insufficient, I ballpark by using a small enough parallel resistor that a values appears in the display...calculating...yupp, big 'ol resister, just like the code on it says...

[GibsonGM]

A cheap analog meter is not strictly necessary but pretty useful, IMHO.  You can use it to watch trends that may seem 'random' with a DMM.  And it can act as your 2nd meter for measuring 2 things at once, such as watching voltage AND current in a circuit.
No need to spend $ there, though, the $5 hardware store one works just fine!   Plus, I use it when I have to install a lamp or change an outlet while doing renovation work - just in case it takes a beating in the toolbox, no worries! 

Just thought I'd pipe that in...

[frank_p]

can anyone point me in the direction of a multimeter that has hese attributes? I cannot find a meter that has both hfe and autoranging.

Canadian-Tire have an autorange one (with no cap/indutor measurer but with Hfe measurement).  I think it's a generic asian type that can be found in many brands.
http://www.canadiantire.ca/browse/product_detail.jsp?FOLDER%3C%3Efolder_id=1408474396672790&bmUID=1185910446726&PRODUCT%3C%3Eprd_id=845524442202151&assortment=primary&fromSearch=true

[Processaurus]

This one looks fun:



http://www.seeedstudio.com/depot/dso-nano-the-pocket-size-digital-storage-oscilloscope-p-512.html?cPath=11

[R.G.]

Measurement is a commodity you buy, just like ... hmm, beer, let's say.

Sometimes you are tired and thirsty, and just want to knock back something cold and refreshing. Sometimes you want to smell and taste the very best, and are willing to pay for it. You can waste a lot of money getting your needs mixed up.

Measurement comes in different degrees, too. Sometimes you want to know if some point is at 9V or 0V. And sometimes you need to know whether it's 4.6 or 4.8V. But sometimes you really need to distinguish 3.727V from 3.728V reliably over a period of hours, and over the course of days or weeks. There's an exponential increase in cost to do each of those steps.

Google the difference between precision, accuracy, and repeatability in electronic measurement. Precision and accuracy are NOT the same. And repeatability is slippery.

We won't even touch on calibration, which most people here will never do.

In most cases, a $5 meter is fine. But sometimes you need that 4 1/2 digit autoranging true-RMS calibrated Fluke.