Isolated Line Voltage Power Switch/Dimmer

Here is an isolated Line Voltage Power Switch/Dimmer designed and built by Charles Wetzel, one of our users in Austin TX. It is arelatively easy and inexpensive circuit, built with all through hole parts and a $5.00 SchmartBoard 201-0001-01. "This line voltage power controller interfaces a DC control voltage or microprocessor logic output to an AC load. By adding a filter capacitor to the input resistors, the circuit may be controlled by a duty-cycle modulated square wave with about 2.5 volts average giving minimum brightness and 3.5 volts average giving full brightness."