From time to time, Harbor Freight puts its Cen-Tech Seven-Function DMM on sale for $2.99. Sometimes, they send out coupons knocking a dollar off that price.
How good are these $2 DMMs? Well, as long as you realize their limitations, they can be quite useful. Here are some ideas about how to use these meters from the subscribers to the Glowbugs E-mail List.
- Glen, K9STH, says, “The test leads are pretty flimsy but at the price when they ‘go’ you just purchase another one. I keep one in my tool boxes and some people keep one in their vehicle.”
- Jim, W5JAI, writes, “I am thinking about mounting one in a power supply I am building with the dial set on volts, hard wired in, with only the LCD face visible through a window in the chassis. Its cheaper than a “real” meter. I will put a small 9V power supply in to replace the battery. Its a cheap way to get a digital display on the power supply. I tried taking it apart to see if I could mount just the internals of the thing, but it would be much easier to just mount the whole thing, case and all, right inside the chassis with a 3/4″ x 2″ opening to view the LCD.”
- My contribution: “I know this is the GlowBugs list, but one feature that I think is pretty cool is the hFE test feature. I don’t know how accurate it is, but if you play around with transistors, you can pop them into this meter and get an idea as to whether or not they’re working before you put them into a circuit.”
- Ian, K3IMW, agreed with me about the hFE feature, and added, “I also like the diode forward voltage test. I have one that I used just for these two purposes. Very handy to identify swapmeet diodes as Ge, Schottky, etc.”
- John, K5MO, cautions, “You’ll get exactly ONE shot at measuring voltage on the resistance scale on the China Freight version. I’ve verified this with several units.”
- Bob, KE6F, says, “They also make cheap panel meters. File a rectangular hole in the panel. Set the desired meter function, pull a pair of leads out the back of the plastic case and you got your digital panel meter.”