Harbor Freight digital multimeters

[Hoomi]

Harbor Freight often offers their cheap DMM's for free on coupons, or for less than ten bucks at normal price. Having worked as a Calibration Service technician for a major aerospace corporation for over 35 years, I didn't have much confidence in an El Cheapo multimeter, but decided to grab one on the coupon and check it out.

While not accurate enough to use as a Calibration Standard, they're plenty close enough to use for basic troubleshooting, and cheap enough that if something happens to it, you're not out much. I brought one to work, and checked it against our calibration standard sources, and was surprised something that cheap, was reasonably accurate.

I keep it in my car, in case I need to troubleshoot a problem with mine or someone else's car, and it saves me from having to keep my Fluke 27 in a hot car all the time. Similarly, with the cheap meter, if someone accidentally or purposefully walks away with it at the flying field, it's not a big fiscal loss.

[quitcherbitchen]

I agree with you, but as you said "not accurate". Both of mine are off by a 1.01 volts when taking DC readings. Usually on the high side.

[Hoomi]

I've checked two against the standards at work (Fluke 5700 Calibrator - precision DC, AC, and Ohms source), and both have been within .2 volts across the range.

We are required to maintain 4 to 1 accuracy on standards over units being calibrated. I.E., if the unit being calibrated requires 10 volts +/- .5 volts, our standard used to measure that voltage must be calibrated to 10 volts +/- .125 volts. The standard used to calibrate that standard must be calibrated to 10 volts +/- .03125, and so on, all the way back to National Institute of Standards and Technology.

That said, the Harbor Freight meters are cheap from China, and one way they keep the price low is by minimal, if any, quality control. It's always a good idea to check them against a known value before depending on them.