Blind crowing device circuit

Published:2011/11/23 21:45:00 Author:May | Keyword: Blind crowing device | From:SeekIC

The blind always feel not convenientwhen they usetiming clock to crow herald the break of a day,so using blind crowing device circuit to make crowing device is very convenient. Transistor VT1 is optical transistor, when it has different illumination, its resistance value changes comparatively large, integrated circuit IC1 (5G1555) makes up free-running multivibrator, its oscillator frequency rises along with the add of lumen output. The oscillator frequency and dutyfactor of oscillator depends on resistor R2, photoelectric cell VT1 (3DU22) and capacitor C1. Resistor R2 ensures the upper limit frequency at about 6.5KHz. Photoduodiode VT1's dark resistor makes lower limit frequency fix at about 1Hz. Sound relationship with the Sky output as follows: Sky output/ VT1 resistor/ frequency sunshine enough/100Ω/6500Hz evening/ 10K/3000Hz starlight/ 10M/ 2~4Hz



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