The photo control electric switch

Published:2011/9/5 22:50:00 Author:Seven | Keyword: photo control, electric switch | From:SeekIC

Working principles: see as the figure, after the 220V AC passes the bulb H and the rectifier bridge, it becomes the DC pulse voltage as the forward biased voltage, which can be added on the SCR VS and branch R. In daylight, when the brightness is over some degree, the LDR D is in a low resistance which is ≤1KΩ, so the triode V is blocked and there is no current out from it, the single way SCR VS is blocked due to the lack of trigger current. At the moment, the current past bulb H is ≤2.2mA, the bulb is not glowing.



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