How to Make a Photo Cell

A photo cell can be made quickly at home.
A photo cell can be made quickly at home. (Image: Resistor image by Andrzej Thiel from

Photocells are used in watches, traffic lights, alarms and much more. Photocells have many different purposes and continue to be used in light, sensitive machines to determine whether or not current should flow to the machine or not. Although the photocell is used in many large-scale projects, you can also make your own photocell quite quickly and easily.

Things You'll Need

  • Propane torch
  • Sheet of copper
  • Salt solution
  • Copper wire
  • Small block of wood

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Heat up a relatively small area of a sheet of thin copper with a propane flame. Continue heating the copper sheet until it is glowing with heat. Let the copper cool for a moment.

Place a drop of salt solution on the copper plate. Make contact with the solution with clean copper wire.

Attach the copper wire to a small block of wood. This will keep the copper wire in place by simply positioning the block of wood near the copper plate. The plate will serve as one terminal, and the copper wire will be the other, which together form the cell. Connect the cell across a volt meter to test the voltage.


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