| 摘要 |
A relay control circuit that includes a zero cross detector, a latch, and a delay circuit. The zero cross detector circuit detects when the voltage waveform or current waveform on an AC power line is at the zero crossing. The output of the zero cross detector clocks the latch (flip-flop), which receives a control signal at its data input. The flip-flop latches the control signal on the zero crossing point and outputs the latched signal to the delay circuit. The delay circuit delays the control signal for a predetermined time period depending on the make and break times of the relay so that the relay is switched ON and OFF substantially near the next zero crossing point of the AC voltage waveform.
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