| 摘要 |
The electronic switch is mounted in series with a load (3) between two poles (1, 2) of an alternating electrical power supply. It includes a triac (10). A circuit (26) supplies the trigger (10a) with a continuous firing signal. In series with the triac (10) are arranged, in parallel, a resistor (21) of the same order of value as the load (3), an avalanche threshold diode (24), a Schottky diode (23) and a MOS transistor (22). A DC source (25) powers the circuits (26 and 28). When the triac (10) receives a firing signal at the start of the positive half-period of alternating voltage, the passage of current in the resistor (21) produces a positive voltage at the node (20), which charges a reservoir capacitor in the source (25). With a delay of about 2 ms in the appearance of voltage at the node (20), the circuit (28) takes the transistor (22) to saturation, the voltage at the node (20) substantially cancelling out. The source (25) is supplied by pulses, without the firing of the triac being delayed. <IMAGE>
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