Opto-Isolated TTL to 110 VAC Power Source

Here is a simple hack to convert a simple (cheap) module into your very own opto-isolated TTL to 110 VAC power source.  Since it is isolated you can control it with low voltage circuitry and have no worry about electrocution. The other concern when you control high voltage with a low voltage control circuit (a computer parallel port for example) is that a failure could cause high voltage feedback which could damage your delicate low voltage gear, have no fear with this circuit since there is no physical connection to the high voltage side from the low voltage side.

"Light-controlled outlets are normally used to light a nightlight when it gets dark. By mounting a red LED directly above the light sensor you can use any digital circuit to drive a 110V load safely opto-isolated from your low voltage control circuit. This Instructable shows a 2-channel module built into an outlet box, but the concept can be expanded to any number of channels in any packaging format. I use a pair of compact 8-channel modules to drive an outdoor Christmas tree display using a Basic Stamp microcontroller.

The light sensor inside these devices is a cadmium sulfide (CdS) light-sensitive resistor which is most sensitive to red-orange light, so light from a low-output red LED is sufficient to make the outlet turn on. The LED can be driven from any control source.

This Instructable shows you how to modify the light-controlled outlet, converting it into a simple module that has a pair of wires for 110V control and a pair of wires to drive the LED. If you don’t want to do the "circuit bending" required to make this module, you can use the light-controlled outlet as-is by merely mounting the LED over the sensor externally. Then you can plug as many modules as you want into a power strip and run your LED wires to a suitable controller."