Triac-based dimming products are perfect for resistive loads such as incandescent lamps. The potentiometer RV2 adjusts the phase angle of the triac. When VC3 exceeds the breakdown voltage of the DIAC, the triac will be turned on. When the triac is turned on, the AC mains voltage is applied almost instantaneously to the LC input filter of the LED lamp power supply. A voltage step applied to the inductor causes oscillation. If the dimmer current falls below the triac holding current during oscillation, the triac will stop conducting.