Nighttime Automatic Illumination Circuit Composed of μA555

Published:2011/9/8 1:48:00 Author:Sue | Keyword: Nighttime, Automatic, Illumination | From:SeekIC

    BG1(3DU5) in the photoelectric switch is photosensitive triode which has different resistance value under different light. In the daytime, it has a low resistance value because of the light which will make BG2 disconnected and BG3 will be connected. The silicon controlled rectifier SCR is disconnected and the oscillator doesn't work because of lack of electricity, and the pilot light is not illuminated. In the nighttime, BG1 will have high resistance value between c and e, which will make BG2 connected and BG3 will be disconnected. SCR is connected and the corresponding oscillator begins to work because the power circuit is connected. Its output signal will drive the pilot lamp ZD to illuminate which will draw people's attention. By adjusting W1, striking flash light interval can be achieved.



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