This little circuit can be used to dim lights up to about 350 watts. It uses a simple, standard TRIAC circuit that, in my expirience, generates very little heat. Please note that this circuit cannot be used with fluorescent lights.
15K 1/2W Resistor
0.068 250V Capacitor
Lamp To Be Controlled (up to 350 watts)
Case, Knob, Heatsink For TR1, Wire, Socket For L1
1. This circuit is for 117VAC only. 220 or 240 V will burn up the circuit. L1 can be a maximum of 350 watts.
2. The circuit must be installed and used in a case.
Source: Electronics Lab