AC power supply dropping rapid detection circuit

Published:2011/4/5 21:08:00 Author:Nicole | Keyword: AC power supply, rapid detection | From:SeekIC

This circuit can detcet whether the AC power supply kicks up rapidly just in 10ms. Source transformer secondary output through full-wave rectifier, filter and triple pin regulator 7812 produce 12V voltage power supply. Rectified ripple waveform is plastic outputed by NAND gate, sensitivity is adjusted by potentiometer, that is allowed drpoped voltage. Normally, in the point A, f=100Hz. Duing to the diode, the discharge time of C1 is shorter than its charge time, so Vc always could not reach the threshold, and the point B always in the 1 state . When K right dial, LED has corresponding instructions. When the power supply is dropped into the set value, the time of A in the 1 state at least increase 10ms, in this period, Vc1 rises, B always in the 0 state, than LED has corresponding instructions too. RC2 is used to delay the instruction time. It can add 100Hz square wave to the first level inverter input terminal directly while debugging.



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