This is a pretty useful device. It is an IR controlled light dimmer. It goes in line with the main power and controls how much gets through to your light. You can adjust the brightness with a TV remote control. Finally, we can retire our clapper! These are commercially available, but making your own is just so much more fun. You may have to dig a little on their site for the schematics and programming. There are tons of other projects there as well so have fun.  You can see a video of it in action after the break.

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SparkFun’s latest tutorial shows you how to work with relays. A relay is an electrically operated switch. In this case, they’re using it to switch a 120V AC outlet. The article carries the standard warnings about how not to kill yourself with AC (plus some non sequitor linking throughout). As an extra precaution, they chose a GFI outlet. You probably know how a relay works, but it’s worth seeing how they implemented it. They use a transistor to prevent overloading the microcontroller’s GPIO pin. The control pin is pulled to ground to keep the relay off. A diode is placed across the relay coil to manage the power flow when it discharges. An indicator LED is included to show when the relay closes. This is a great foundation for an automation project, or maybe you just want to terrorize your cat.