350W Lighting Control Circuit with TRIAC

350W light control circuit

This is the kind of common drive widely available in hardware stores and home improvement stores. The circuit is a basic model for light dimmer for 120V AC voltages. The basic design of the bulbs can power range from 30W to enter the order of a few hundred watts (depending on model).

The objective of the pot P1 and C2 in a diac / triac combination is just to delay the ignition point of the DIAC crossing zero. The greater the resistance (R2 + P1) feeding the capacitor C2, the longer it takes the voltage across the capacitor at the point where increasing the diac D1 fires turning on the triac TH1. Capacitor C1 and inductor L1 a simple filter Radio Frequency Interference. Without it, the circuit to produce, because a lot of problems, firing of the triac in the middle of AC phase causes fast rising current surges. The triac TH1 can resist 6A DC current when cooled properly, so that the circuit would be able to handle about 300-500W of power when a small heat sink is mounted TH1. If TH1 is not cooled, the maximum is probably around 150W.

Component

R1  50K Pot 
R2  15K 1/2W Resistor 
C1, C2   0.068 250V Capacitor 
L1   Lamp To Be Controlled (up to 350 watts) 
L2   Neon Lamp 
TR1  40502   TRIAC