Whats your favorite DMM?

Robotics and electronics discussion Resources
1

Arguably the most important tool in robotics, everyone should have a good multimeter, but there are lots of overpriced pieces of junk around. To be sure you get a good meter, you could go spend $200 on a Fluke, but I thought it would be neat to generate a list of favorites, particularly inexpensive ones.

Personally I’m partial to Velleman DMM’s. After a string of disappointing Radio Shack brand meters, I picked one up from a kit website (it was the only one they carried, and I wanted to max out my shipping) and got very lucky. They have unexpected features for their low price, with quite decent accuracy, and they look and feel like quality instruments (around here we call them fluke-a-likes).


For about a year now I’ve been keeping a Velleman DVM850BL in my desk drawer for daily use, and it is definitely still my all time favorite, mostly because I got a great meter for just $15 (about the price of the lame plastic rectangle meter at your local gas station!). It’s small (comparable to a gameboy) but it’s got all the normal features: DC Voltage and current, AC voltage, resistance, diode continuity, and a diode tester. It also has data hold and a back-light, which at first I thought were really really cool, and then never ever used. But, I recently managed to destroy the (unfused) 10A DC current circuit on mine, so I thought it was time for something new…


I just picked up a Velleman DVM890F, sort of the full-size meter big brother of my old DMM. For $40, you get the features of the little guy above (minus data hold and the back-light) plus capacitance, frequency, temperature (ambient and thermocouple probe), and AC current. I’m excited about temperature (it is 70F in my office right now) and frequency, but the real deciding factor was capacitance, which I really missed not having in my smaller meter. After playing with it for a day I’m quite satisfied.

So, anyone else have a DMM gem to share?

-Adam

2

I survived w/ a shitty 15$ multimeter for quite awhile… but eventually I couldn’t take it anymore. It had horrible input impedance, so that you had to keep track in your head what the voltage SHOULD be, not what the DMM read out. Grr.

So I bought a fluke 110 on ebay. It cost me $70 and it was worth every penny. Auto ranging is very nice. As well as the Max/Min functions.

Now my next purchase is an oscilloscope. You should see Pololu’s… its pretty hardcore.

3

Wait wait wait! Pololu sells oscilloscopes? HMMM!

I loaned out my meter (and my soldering iron) and neither one came back, so I’m in the market for both of those right now. (I get the feeling electronics tools are a little like books. You don’t loan out a book, you give it to someone. Only books I’ve loaned out that that’s not true for are my Sandman books. Can’t afford to replace them.)

But so far I’ve been borrowing a scope from one of the engineers at work. Pretty sure it cost more than my car. But the soldering iron thread and this thread have me believing maybe I can replace my permanently loaned out equipment and afford it, too.

Tom

4

Yeah, I know what you mean. I’ve got a great ancient O-Scope at work that works fantastically well, and even grabs screenshots to a floppy disk. It probably cost more than they pay me in a year. If anyone has firsthand experience with a nice scope in a reachable price range I would be seriously interested!

Actually, Jameco likes to give away my little multimeter (DVM850BL) with their scopes.

-Adam

5

sorry benedict, I meant the oscilloscope they USE. As far as I know they aren’t selling any :slight_smile:

6

Ah… (Oh rats! :wink: )

Tom

7

Hello.

We’re don’t sell any scopes (yet!). I’ve had good results with a cheap Instek (GDS 0806) that I got for around $650, I think. For just two channels, color doesn’t seem that useful, and it has more memory at slower speeds than the Tektronix low-end scopes, so it’s nice for looking at things like serial data.

Saelig has a scope on sale for $329 (http://www.saelig.com/miva/merchant.mvc?Screen=PROD&Product_Code=PSSA002&Category_Code=); I have no idea how well it works, but the price is the lowest I’ve seen.

- Jan

8

Has anyone used one of those little USB oscilloscopes? I like the idea of it, but I would want to hear from someone who had used one.

They range in price a lot, but Parallax has one for under $150. Looking at it’s specs, the sampling rate is quite low.

-Adam

9

I did some more reading about USB scopes, and particularly the one from Parallax got good reviews, and I suppose it’s a lot of performance for the price, but it’s still pretty darn slow (you can’t look at USB signals in real time with a USB scope after all). I also came to the conclusion that I really wanted something with its own buttons and knobs rather than something I had to mouse click and drag.

That Owon scope Jan found does look pretty nice (especially the color screen), and I was hoping for something with that compact LCD form factor (not one of those old CRT dinosaurs) but the bandwidth is still just a smidge low. It would probably be just fine for anything I would ever do with it, then again I’m not so sure that just four samples make for a great reading.

Forgoing the color screen I decided to go with the brand-name sure thing, the Tektronix TDS 210, aka the single most common oscilloscope on e-bay (~$500, +/- $100). It’s got 2 channels (the third BNC post is for an external trigger), 60 MHz bandwidth, and takes 1gs/S. It has all sorts of automatic ranging, measurements, math functions, self testing, and an expansion slot for things like a printer port (yes, it has a ‘hardcopy’ button). A friend of mine has one and loves it, so I took the plunge:

I’ve been playing with it a bunch this afternoon, and I’m really pleased with it, plus I’m surprised at how intuitive it is. The only odd thing I’ve found so far is that when you’re in the cursor menu you use the level knobs for channel 1 and channel 2 to move the cursors. Once you realize that, it’s actually nicer than using a single jog switch to move one cursor at a time. It took me forever to figure out though, even on the fancier (4 input, 100MHz, 2Gs/s, color screen) TDS 2024 scope I use at work, and that one even has little LEDs that light up under the knobs when you enter the cursor menu.

The one thing I wish this had was a way to save images of the screen at the press of a button (the TDS 2024 at work has a CF card slot for this, and the older but still very nice dinosaur CRT TDS 540 has a floppy drive). This guy doesn’t seem to have any expansion modules for that, one has a serial port though, oh well. All in all though this looks like a great beginner/intermediate oscilloscope to me.

-Adam