OK Cheap DC Clamp Meter

Post by **leadwings** » Thu, 10 Mar 2011, 18:16

I wanted a cheap DC clamp meter to be able to get an idea of what currents were running where without disconnecting stuff etc. My car was built and up and running, so it was more a nice tool to have rather than a must have analytical tool, and being a TA I didn’t want to spend $100+ for a super accurate meter.

I bought a $40 one from e-bay, and it was rubbish. 3 - 4 A reading with no wire through the loop, and drifted constantly.

I thought I would try again, and got one of there from DealExtreme for US$38 delivered:

http://www.dealextreme.com/p/uni-t-ut20 ... -max-15220

So far I have been impressed – 40 A and 400 A ranges, and on the 40 A range the bias is only 0.1 - 0.2A, and can be cancelled out with the delta button. Drift is again only 0.1 A, so the sort of thing I am looking for (0.5 A plus stray currents) it is more than good enough. I have not tried to calibrate if the readings are accurate, but again super accuracy is not what I am after.

So for the cost I would recommend it.

Post by **acmotor** » Sun, 13 Mar 2011, 06:36

I have the same meter. Snap. I bought one off ebay about 18 months ago for $37 inc. post.
Rather handy item.
I checked it against my RMS fluke (doing direct current through meter) and it is within 1% on smooth DC though can be 5% out with PWM DC as the uni-t is not true RMS reading.
The clamp is sensitive to PM fields and actual wire position through the clamp. (as many clamps are)
It is rather useful with its physically small clamp and I would say small is good for clamp meters as you often need to squeeze them into a wiring bundle. I have used plenty of 600A clamps that are like using blacksmith's tongs.
The LCD display is a bit angle sensitive in contrast but yes, for the money, quite a useful item.
The auto powerdown is good sometimes and other times a real pain. Can it be turned off ?

Post by **leadwings** » Mon, 14 Mar 2011, 16:49

Yes the auto-off can be turned off - from memory you hold the select button down when you tuarn it on.

Post by **coulomb** » Sat, 07 Dec 2013, 02:16

I also ordered one of these, and it's just arrived. Seems pretty good. Took 13 days to arrive.

I find that on the 40 A DC range, the reading varies by up to about 15 counts, which is 0.15A, in the time it takes to make a reading. A lot of the time it's less, perhaps 5 counts. I find this quite usable.

To those of you that have owned one of these for a while... does it stay as stable as this as it ages? My fear is that it will with time become like Weber's clamp meter, whose readings on the 40 ADC range vary by some 7 amps (700 odd counts) in the time it takes to make a reading, which makes it useless for all but the most gross current readings.

Edit: cost AU$44.85; US$38 plus the usual credit card ripoff exchange rate.

Edit2: Weber claims that his meter's drift is more like 1.5 A in 30 seconds; the initial offset was 7 A. And he's managed to reduce that to 2 A by futzing with a magnet.

Post by **BigMouse** » Sat, 07 Dec 2013, 05:16

I've had one of these for a couple years now, but I've only used it rarely. I recently tested it on AC against a calibrated clamp meter and got values that were reasonably close. I wouldn't use it to calibrate anything else, but it's more than good enough for general testing.