Picture of Laser Pointer Switch

This instructable will detail how to make a switch that uses an arduino to sample light. When the light sample reaches a threshold it will trigger a relay that can be used to turn on/off a small appliance (light, radio, fan, etc...) The parts for this instructable can be ordered as a kit:

Jameco Kit

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Step 1: Review relay and prep wire

Picture of Review relay and prep wire

unpackage the relay and stretch out the cable. this cable is used to activate the relay but will also be used to power the arduino. cut the wire in about two equal parts. the part with the white clip end will plug into the relay and be soldered into the arduino. the wire with the black clip end will be spliced into the usb cable to supply power to the arduino. this is also a good time to review the relay tutorial for safety information:

Step 2: Modify USB cable

Picture of Modify USB cable
cut the USB cable about 6 inches from the end with the rectangle end.  strip the wires and you will find a red, black, green and white wire.  splice the red and black wires from the relay cable (with the black end) to the red and black wires of the USB cable.  solder the connections and tape the wires.  this new USB cable will be used to power the arduino.

Step 3: Identify Arduino

Picture of Identify Arduino
find the arduino in the kit of parts and familiarize yourself with the pin holes and orientation of the package.

You can use LEDs as sensors - the high power ones have a large sensitive surface.

There is something ironic about using a light sensative switch to turn a lamp on and off. lol

Nice Instructable!

nodcah1 year ago
Nice instructable! Now all I need to do is integrate it into the light switch itself!

Nice, I want to build this so I can turn off my lights without getting out of bed!