DIY Copper Style LED Painting Illuminator

Step 8 Make it light sensitive

In this step, I'll show you how you can give your Copper Style LED Painting Illuminator an eye in the form of a LDR and a couple of other components. If you don't want or need this auto turn-on feature, you can skip this step.

Here is a video showing the Copper Style LED Painting illuminator with this light sensor in action.

The sensor has been adjusted so that when the ceiling light is turned off, the light bar turns on.

Note: from the the point of 00:22 and to 00:48, it's flashing because I'm waving a small flashlight over the light sensor.

Here is what you need to make it.

• An LDR. Also known as a photoresistor, photocell or CdS cell.
• An LM358N low power dual OpAmp.
• An 8 pin DIP socket for your OpAmp. This is not strictly neccesary, but it's reccomended
• A 10kohm resistor.
• A 1-10kohm resistor. This resistor is used to limit the current going through the base of the transistor. The resistance of this resistor can be from 1-10kohm. The transistor doesn't care.
• A 10kohm trimmer potentiometer. Can also be a normal potentiometer.
• An NPN transistor. This project just requires simple on/off switching, so almost any NPN transistor will do. Here are some examples of some the transistors, you can use: 2N2222, BC337, S8050, BD139 and many others. Just check your transistor's datasheet to make sure, that it can handle the power needed for your fixture. My circuit uses a little less than 500 milliamps, so I used a BC337 because I already had some lying around.
• A small PCB to solder all the components onto.

The schematic is pretty straightforward.

You can control at which brightness it turns on by turning the potentiometer.