A simple voltage dimmer circuit that can be used to adjust the output voltage between 0 and 220 volts, can be made using electronic diagram below.
This voltage dimmer circuit can be used to control up to 300W using F407 diodes. Power controlled by this circuit is according to the type diode and thyristor used.
Variation of voltage across the load R is adjusted between 0 and 220 V, with a 150k potentiometer which command Th thyristor conduction. Depending on the time as thyristor is “opened”, the bridge diode drive current through the load.
Using F407 diodes can be controlled a power up to 300 W. Thyristor must admitted a current of 5 A.