DIY Voltage Test Meter with LED Display

If you are interested in making a DIY voltage test meter, you can take a look at this article.

If you happen to have a battery level tester, its window is just the right size to fit a 0.28-inch LED display module.

For a three-wire meter, if you convert it into a two-wire connection, it can only measure voltages above 4V.
To measure voltages below 4V, you need to provide separate power to the display module.

The mechanical meter head can only provide an approximate measurement.
You can make use of its outer casing.

Disassemble this part, and you will find a meter head inside.
There is also a small circuit board on the meter head, which contains voltage divider resistors.

This meter can measure 1.5V and 9V batteries.

Remove the mechanical meter head core, and you will find that it fits the LED display module perfectly.

Three-wire connection method (separating power supply and voltage measurement).

Add a lithium battery to provide power for the display module.

Use a 4056 charging module.

The project is completed.

Testing.