Choosing a multimeter

May 28, 2005 11:40 AM

I'm ready to make the plunge into electronics repair/circuit building but I'm wondering what I should look for in a multimeter and electronics tool kit?

Aside from auto-ranging, I'm not sure what features to look for in the multimeter, and are there any particularly good reasonably priced tool kits?

posted by drezdn to science & nature (18 comments total)

Autoranging is good. Robustness is also good. I wouldn't try to get extra features (temperature probe, etc.) unless you have a specific need for them.

I bought a Fluke DVM, on the strength of the company's reputation (nearly a decade ago now, when I had less money...) and though it was more expensive than most of the alternatives I've been quite happy with it.

What kinds of things are you expecting to do? Electronics repair as a business, or DIY home repairs? Circuit building: audio, computers, robotics, industrial?
posted by hattifattener at 1:10 PM on May 28, 2005

The TPI 183 was about $150 and worth every penny. I wouldn't go with the kits, because you need a multimeter to test them.

It should measure volts, resistance, ohms, have a diode checker. It should have auto-ranging (like you said), no greater than 0.5% tolerance. That's the bare minimum.

Oh, and make sure it has good leads.
posted by schnee at 1:13 PM on May 28, 2005

Scratch that kit comment. I thought you were referring to buying a multimeter kit. That's what I get for reading too quickly.
posted by schnee at 1:15 PM on May 28, 2005

I've been looking for a good multi-meter too, though strictly for occasional hobby use. What does auto-ranging mean?
posted by autojack at 1:32 PM on May 28, 2005

I usually start a hobby and am intensely interested in it for a few months, then I find another hobby. So if you are anything like me, I would get an inexpensive multimeter - like the ones from radio shack, until you are absolutely sure you are going to stick with it for awhile. I really don't think autoranging is that necessary starting out as a hobbyist. necessary are current, voltage, resistance, and diode checker (maybe a logic probe as well.)
posted by bigmusic at 1:37 PM on May 28, 2005

Auto-ranging means that you don't have to set the upper and lower limits of what you're measuring.

For instance, on meters that aren't auto-ranging, if you were measuring DC voltage, you could put the dial on 1-5V, 12-24V, and so on, depending on what it is you're measuring.
posted by odinsdream at 2:11 PM on May 28, 2005

If you go for a low-end one, make sure you don't buy one with hardwired probes, since you may want to attach different shaped ones.

(This is the only problem I have with my ~$20 one)
posted by cillit bang at 2:15 PM on May 28, 2005

As for opting for one without a temperature probe, you should know that it's great for making chocolate candy. Or, any candy, really...

I like the temperature probe.
posted by odinsdream at 2:28 PM on May 28, 2005

I buy cheap multimeters all the time for my students, and for the last couple years I've been purchasing the following from all electronics for 17.95

autoranging is nice but also (in my experience) not that important, certainly not $100 worth of important.

I highly recommend buying an oscilloscope as well. A couple hundred bucks on ebay will find you a used Tektronix analog scope. Once you learn to use a scope debugging and fixing will be much much easier.
posted by puppy kuddles at 3:00 PM on May 28, 2005

I have a pair of multimeters. I have a nice expensive (but dated) Fluke multimeter and an el cheap that I received in university with some of our IEEE Student Chapter beer bust funds. My cheap one does everything I need to and it's lasted 14 years so far. Removable leads are a good idea, not just because you'll want to try different tips but also because if you're dealing with high voltage it's easy to accidently short out the circuit and melt a chunk of your probe.

I've never done it, but a landlord who borrowed my multimeter did. Fortunately it was the cheap one.

My Fluke autoranges but to be honest I don't find it all that useful. I usually know roughly where to start and I can dial down as quick as it autoranges anyway.

I also purchased an oscilliscope, 40 MHz bandwidth, on eBay. I think I spent 250 on it.
posted by substrate at 3:39 PM on May 28, 2005

Personally, I buy cheap. Usually Radio Shack or All Electronics has a sub-$20 autoranging multimeter that does AC/DC/ohms/continuity/diode with removable probes. Why do I buy cheap? Because I've blown 3. The last one was trying to check a neighbor's electric fence, which spiked just a little too hard for the poor little meter, but I was only out $20. I'd weep if I lost a Fluke. Flukes are fabulous machines, and I love their reliability and their old slogan ("If it works, it's a Fluke!"), but not the Cadillac price.

Second on tracking down an old o-scope.

Also, if you can, buy another set of probes and solder alligator clips on them or at least on the ground probe. It will helo solve the 3-hand problem.

As far as a toolkits are concerned, get a good soldering station (I'm a fan of Weller for that), small diagonal cutters, needle node pliers, and a pair of wire strippers that you can live with. I personally like this kind of wire stripper as I hate trying to recall the wire gauge or work with adjustables. I can feel when I'm through the insulation of a wire and that's good enough for me.
If your getting a set of screw drivers, get hardened steel. Most of the cheaper toolkits come with screwdrivers that shred quickly. I'd rather shred a screw than lose a screwdriver.
posted by plinth at 5:59 PM on May 28, 2005

The difference between building circuits that don't work, and building circuits that do work, is a solderless breadboard and jumper kit. ($20 should cover both at radioshack). If you pick up a soldering iron for anything that isn't up and running on the breadboard, you're entering a world of hurt and frustration. If a circuit isn't running, and it's on a breadboard, you can easily swap out and modify it until it is working - it's so quick that even trial and error can sometimes be a viable technique (though not a recommended one! :) Once it's working on the breadboard, not only is it almost guarenteed to work when soldered together, but if it doesn't work it's far far far easier to troubleshoot and fix.

As for multimeters, in addition to the usual (volts, amps, resistance, etc), for repairs (and trouble-shooting your own circuits) it's good to have one that sports a logic probe function, and a capacitance meter (less common) will allow you to identify unmarked caps, and to check that caps are functioning correctly. A beeper or buzzer for continuity indication is normal in all but the cheapest meters, but is absoletely essential, so it's absence would be a dealbreaker. A hi/low hold function is sometimes useful for the same reason as the buzzer - for some measurements it means you don't have to be watching the meter while taking measurements, and can instead concentrate on sticking the probes in the right place :)

I use a seperate transistor tester (and I use it very very rarely), so I don't really know how useful it is to have one on the meter. It can only help to have one, just so long as it's not a big addition to the price.
posted by -harlequin- at 8:35 PM on May 28, 2005

Oh - and alligator clip cables! (those short lengths of wire - 1-2 feet, with an insulated alligator clip on each end). You can never have too many of those. You can get a pack of 10 for $3 (though they're probably more at radioshack).

It's also useful to buy an extra pack, and cut a bunch of those cables in half and solder the wire end to stiff wire, such that you can plug the alligator clip into any pin of the solderless breadboard, thus you can hook up components that lack pins (such as potentiometers) to the breadboard via these wires that have a pin at one end and an alligator clip on the other.
posted by -harlequin- at 8:42 PM on May 28, 2005

I actually prefer wirewrap to breadboard, though it's fairly pricey. The breadboard has the advantage that it's reusable but it's also a fixed size. If you run out of terminal strips you have to buy another breadboard. The connections are also dicey and add more parasitics in my experience.

The wirewrap tool is expensive for what it is, but I got a couple freebies from work. The wire is also fairly pricey but I like to keep spools of a few different colours so that I can keep better track of what I'm connecting.

The only consumable with wirewrap is actually the wire, though you can sometimes reuse it if you unwrap it carefully.

The perfboard is fairly inexpensive and is available in pretty arbitrarily large boards. Because there's no connections on the board (as opposed to each row in a breadboard being connected) you can fit a lot more stuff on one even if the size isn't larger.
posted by substrate at 9:31 PM on May 28, 2005

Don't get autoranging. It just slows down the settling time. This is especially problematic on cheap meters, but probably true on modern expensive ones too.

If you don't plan on running around with it, one of the old bench multimeters on ebay is a good idea the Fluke 8012A is an old standard, often selling for way under $50. It is better than your average cheap handheld for lots of reasons, but especially because it measures RMS and it has a special mode for measuring very low resistance.

There is some good discussion on redflagdeals if you search for multimeter, also, this cheap meter looks very interesting, but I know nothing about it personally.
posted by Chuckles at 10:39 PM on May 28, 2005

Tastes vary, I guess — I have my nice meter and a couple of el-cheapos, and the first thing I miss on the el-cheapos is not having to switch ranges all the time. I agree that the continuity beeper setting is really, really handy though. You never have enough hands.

Second on Plinth's recommendation of a decent soldering iron/station if you have the $. I recently sprung for a Hakko, which is nice. I got along fine for a number of years with a less expensive iron, though. (But not too cheap: the $5 surplus-bin specials were more trouble than it's worth.)
posted by hattifattener at 10:59 PM on May 28, 2005

Substrate & drezdn:

I don't think it matters so much which kind of prototyping approach you prefer, the really really important thing is to have what you need to make prototyping quick and easy enough that you will do it almost always, thus resisting the temptation to skip that step, for that way lies only suffering :-)
posted by -harlequin- at 6:28 PM on May 29, 2005

My first meter was a cheap analog type (FET input.) Finally I saved up for a pretty good one: B&K, with the usual ranges plus capacitor meter and frequency counter and transistor HFE, all of which I constantly use. Their present model 388B looks like the one I have.
posted by billb at 12:05 AM on June 22, 2005