555 anti-interference light control circuit

Published:2011/5/23 22:20:00 Author:TaoXi | Keyword: anti-interference, light control circuit | From:SeekIC

General optical circuit's photosensitive sensor is in the critical state in the evening or early morning. And the night lightning or the daytime clouds will cause the frequent movement of the relay controller, the anti-interference performance is poor. This controller can solve the above problem. As the figure 17-31 shows, the photosensitive sensor uses the 3DU type photosensitive tube. When the illumination is weak, the 3DU tube presents the big impedance and big depressurization, DW1 will not bebroken through, VT2 cuts off. At this time, C1 is charged through RP2 and R2. After the delay time of td1=1.1(RP2+R2)C1, 555 resets, pin-3 has the low level voltage, and IC2 sets, VT3 conducts, J closes.



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