US Patent 7119497 Dimmer for resistive or capacitive loads

A power dimmer for an A.C. load comprising, between two terminals, two one-way switches connected in anti-parallel and controllable to be turned off and turned on, each switch being controlled by a driver circuit setting the turn-off times of each of the switches with respect to a reference value, each driver circuit being associated with a supply circuit comprising a voltage storage element in series with a one-way rectifying element, all in parallel with a voltage-limiting element, the two supply circuits being connected to each other by a capacitor and the respective supply voltages of the driver circuits being sampled across the respective capacitors of each supply circuit.