Remote control for lamp or appliance
Posted on Jul 19, 2012 8107
The circuit uses the primary current of a small 6 volt filament transformer to actuate a triac and energize the load. When switch Si, in the six-volt secondary, of the transformer is open, a small `magnetizing` current flows through the primary winding. This magnetizing current may be large enough to trigger the triac. Therefore, a shunting resistor, Rl, is required to prevent such triggering. Rl, is adjusted for the highest resistance that will not cause theitriac to trigger with SI open
When single-pole remote switch, SI, closes, the secondary of the transformer is shorted and a high current flows through the 120-volt primary. This triggers the triac and energizes the load. When the triac conducts, current through the primary stops and thus prevents burning out the transformer.