A galvanometer is a device that measure charges such as in a battery or power supply.

Step 1: How to Video

Materials

Plastic Bottle, copper wire, wire screws, tape, straw, magnet and stiff wire for the straw to pivot on.

Step 2: Optional

You can a wooden case for it and add wire nuts to make testing voltages easier.

https://www.youtube.com/channel/UC3gqx2zhUyLdeGIAFyiwPYg