Review on 📊 High-Quality SMAKN 2-Wire Green LED Panel Digital Display Voltmeter for DC Voltage Range 4.0-30V by Ronald Noel

The design of this meter is small. The PCB traces are on the top of the board, so the connector has no mechanical support. The only thing holding it up are the tracks stuck to the disc's substrate. This means that it can withstand very little stress. When mine failed I simply cut the connector off the wires and routed them along the side of the board and through the holes on the bottom. This creates a mechanically much stronger connection. In fact, there's no point in having a plug there at all. The beauty of this is that it includes a trimmer to calibrate the gauge and is already calibrated to a reasonable tolerance. At least as many as you can expect from three digits. There is a diode there that prevents negative voltage from reaching the chip, and if you disconnect it you disconnect the chip's power supply from the main sample input. If you power it with an external power supply, you can measure down to 0 volts, which has the added benefit of not loading what you're trying to measure. You can probably use this to measure voltages over 30 volts, but I don't have a power supply powerful enough to test it with. Aside from being unplugged, my only other complaint is that the display is WAY too bright. It seriously brightens up a dark room. I could fix this by swapping out the 6 SMD resistors, but that's really more trouble than it's worth.