Dimming control system for electronic ballasts

An arrangement, comprising:

• a wall-switch assembly, comprising:
• a first rectifier having an anode and a cathode, wherein the anode is coupled to the first end;
• a second rectifier having an anode coupled to the second end and a cathode coupled to the cathode of the first rectifier;
• a first normally-closed switch coupled in parallel with the first rectifier;
• a second normally-closed switch coupled in parallel with the second rectifier;
• a controllable bi-directional conduction device having a first conduction terminal, a second conduction terminal, and a gate, wherein the first conduction terminal is coupled to the anode of the first rectifier, and the second conduction terminal is coupled to the anode of the second rectifier;
• a voltage triggered device coupled between a node and the gate terminal of the controllable bi-directional conduction device;
• a triggering resistor coupled between the node and the anode of the first rectifier;
• and
• a triggering capacitor coupled between the node and the anode of the second rectifier;
• and
• a ballast for powering at least one gas discharge lamp at an adjustable illumination level, wherein the ballast is operable to adjust the illumination level in response to a momentary opening of at least one of:
• (i) the first normally-closed switch;
• and (ii) the second normally-closed switch.

An electronic ballast for powering at least one gas discharge lamp at a variable illumination level, comprising:

• a pair of input terminals adapted to receive a supply voltage from a conventional source of alternating current, the supply voltage having a positive half-cycle and negative half-cycle;
• a pair of output terminals adapted for connection to at least one gas discharge lamp;
• an inverter circuit coupled to the output terminals and operable to provide an adjustable amount of power to the gas discharge lamp;
• a dimming signal detector having a pair of inputs coupled to the ballast input terminals, and a detector output coupled to the inverter circuit, the dimming signal detector being operable to:
• (i) monitor the supply voltage at the input terminals of the ballast;
• (ii) provide a dimming control signal at the detector output, wherein the amount of power provided by the inverter to the gas discharge lamp is adjustable in dependence on the dimming control signal;
• and
• (iii) adjust the dimming control signal in response to a truncation of at least one half-cycle of the supply voltage.