Dimmer switch for phase angle method

摘要

The circuitry (10B) has a microcontroller (U1) controlling power semiconductors (Q1, Q2) that are arranged in series with a load (6) i.e. illumination device, at an alternating voltage system (7). A zero crossover recognition unit (1) synchronizes the microcontroller with zero crossover of sinusoidal net alternating voltage. A phase angle (Phi) is derived by a resistor and/or capacitor combination with a resistor (R3) and a capacitor (C1) that lies in series to the resistor. The capacitor is discharged by the microcontroller to an end of half wave of main voltage.