12 Volt Photocell Project

Now that our solar panel is complete I wanted to put it in a real world application. I decided I wanted a dusk to dawn light in a remote area on our property. All I need now is a battery, charger, light, and a 12 volt photocell to turn the light on at night and off in the morning. I decided to build my own photocell. This is a fun and easy project if you want to build your own photocell and the total cost is less than 10 dollars.

Here is a diagram of the 12 volt photocell circuit I used. It's built around the 555 timer. Pretty stright foward. The sensitivity can be varied by changing the resistance of the 4.7K resistor. You can buy all the components at JAMECO.com

This diagram shows the circuit board layout I used. This is the bottom side of the circuit board. The components are lightly shown on the opposite or top side of the board. After several request on how to make the printed circuit board I have added a page on how to make a homemade printed circuit board.

The enclosure for the 12 volt photocell circuit board is made from a 3/4 inch pvc pipe adapter and pipe cap with a piece of 3/4 inch pvc pipe. The printed circuit board is 3/4 inch wide and 1 and 1/2 inches long. The piece of 3/4 inch pipe is 1 and 1/2 inches long.

This picture shows the pieces fitted together. At the top of the pipe cap drill a hole through the cap and the piece of pipe. I used a 1/4 inch drill. This size may vary depending on the size of cds cell you use.

This picture shows the hole for the cds cell and the completed circuit board. When you attach the cds cell to the circuit board leave it long enough to come flush with the outside of the pipe cap when assembled.

Here is the completed photocell. When I put it together I started by putting the cap and pipe together with the hole aligned. Then I bent the cds cell leads so they would have some spring to them so it will spring into the hole and come flush with the outside. Then you can slide the adapter over the wires and onto the pipe. Fill the inside with silicon until it begins to come out arount the cds cell. Let the silicon dry and you are finished.

For some reason the pictures are only showing a red and black wire but there is also a blue wire. The red is positive, the black is negative and the blue is the load.

For the load I would use a 12 volt relay.

Here is a one line diagram of the finished solar panel photocell project.

If you would like to share with others your photocell project then add your project here.