diymore10pcs Mini Digital Voltage Meter DC 2.5~30V 0.28" 2 Wire Digital Voltmeter Gauge Tester Green LED Display Panel Mount Car Motorcycle Battery Monitor Led

Update 9/20/23: I bought a set of M2 screws, nuts and washers here on Amazon (Pzsmocn 300 Pieces / 100 Sets M2 Black Nylon Screws and Nuts Kit with Nylon Washers). Just enough room for the nuts to fit against the PCB and clear the components. I would still recommend nylon hardware so that there's no danger in something shorting out.(Original review follows)I'm planning to add these red and green displays to a couple of interface boxes I'm building that powers some IP cameras. I have a mix of 5VDC and 12VDC cameras I'm using so I needed something that would cover this voltage range. One box I have has 12V going in and a couple of USB ports as output. Another box is also connected to a 12V power supply but one output is a constant 12V (powers a WiFi bridge), while the other output is on a time delay which gets power 7 seconds after the bridge does. It would be nice to see what the voltages are going to the cameras, rather than use an LED which would light up as long as there's 3V or so.I connected them to power from a USB port and calibrated each one to match what my voltmeter said (5.05V). There were only a couple of them that initially displayed around 4.90V but all of the others were within 50mV. I adjusted all of them to the same 5.05 using the tiny trimmer potentiometer on the back. After calibration, I sampled a couple of them at 12V and they were fine. I also tested the lower operating voltage the best I could. Two AAA batteries in series is 3V and both the red and green displays lit up showing 3.00. I don't know if they meet the published 2.5V (red) and 2.6V (green) limits as I don't have an adjustable bench power supply but they do at least work at 3V. As I'm planning to use these with 5V and 12V, I'm not concerned with anything below 4.5V or so but I thought this check might be useful to others.Now my problem will be to cut out a rectangular hole in the plastic project boxes I'm using so I can mount the displays. A small hole at each corner and a cutting wheel on a Dremel should do the trick. I didn't see it anywhere here in the product description, but the holes in the mounting tabs look to be a shade over 2mm in diameter so in theory M2 bolts would work. However, the area around the holes are occupied by some components so I don't think you could get a bolt or nut in there. Plus, the holes are almost right in line with the ends of the LED display. The mounting tabs was one of the design features that led me to buy these. It would have been nice to have the tabs a little wider which could allow the holes to be a couple of mm away from the LED display. I may have to hotglue or superglue the displays in place, rather than use hardware.The only other "bad" thing to report is that one of these voltmeters has a semi-delaminated mounting tab; the PCB material has separated in a middle layer but I can probably use some superglue and bond it back together. It didn't affect the operation of the display. Yeah, the display.... They are BRIGHT. I wish that there was a way to turn down the intensity but I guess it's better then being too dim to read.

All tested good. Suggest a dab of hot glue on wire soldering point.

I use a lot of led volt meters in my buisness and these work just as good as the more expensive on the market. Go9d Deal!

Hasta el momento, continúan respondiendo bien, los uso en el mini proyecto solar.Calidad aceptable.

These are useful small panel meters, I expected ballpark accuracy and that's what they are. 3% is the spec, and that is ballpark on my book. They are adjustable so can be "calibrated" but bear in mind at the specified 3% accuracy, the thrid digit is just close. These are indicators, not test equipment,They were perfect for the small dual rail tracking bench (not lab) power supply I built. It is much more accurate than the meters but in the rare case the circuit under test needs more accuracy than these little meters... bench DVM.All five meters work. I opted for multiple colors so I can tell at a glance what/which quantity I am observing. Three wire meters were also needed for my application because I wanted to measure close to zero (0) Volts and over 40 volts.When i need more I will not hesitate to get more of these.

Works until it hits 16v then stops working. They are rated up to 30 volts but that can’t be true. I had several replaced when they died. Luckily the pack came with so many I was able to replace on the fly. Will not work as advertised

The media could not be loaded.  But it's exactly what I needed.My video should show U the size of this display. IT IS SMALL ! But some designs need a ultra small display. I'm quite pleased with this. The wiring was flimsy @ best so I did take the time to re-solder the 3 wires which I suggest everyone should do so u won't have to rip ur project open later and do a re-solder.

Simple and works. Accuracy is OK and can be adjusted pretty easily to a known reference.Main problem is the wires are.....very.....small, stiff even at that size, and break off easily, generally right at the display solder attachment.They are inexpensive, but better wire would save a lot of hassle soldering them back on and stabilizing the wire with hot glue.