Small and self-powered, this green LED voltmeter is a handy monitoring module.
We've had situations where we want to watch a voltage, but don't want to dedicate or mount a full meter to the projects. This little device fills the need. Small, compact, self-powered and inexpensive, it lets us watch for system voltage sags without using up our bench meters.
If you have to install it a distance from your measurement point and you are concerned about voltage drop, there is a trimmer on the backside so you can dial in the compensation for the line loss powering the display. That said, please calibrate your unit before using it!