Light-Operated Streetlight (13)

Published:2011/7/5 23:37:00 Author:Sue | Keyword: Light-Operated, Streetlight | From:SeekIC

In the evening, RG has a high resistance value because of lack of light. A's electric potential becomes higher and higher. IC1's pin 6's voltage is higher than 2Vcc/3. Its pin 3 outputs low level. VD1,VD3 and V are disconnected and VD2 is connected. B will have high level and IC2's pin 6's voltage is higher than 2Vcc/3 too. IC2's pin 3 outputs low level which will make VT connected. EL is illuminated. At the same time, C3 is discharged slowly through R6,R7 and RP2. Then IC2's pin 2's voltage becomes lower and lower. Time delay is about 4.5-6.5h. When IC2's pin2's voltage is lower than Vcc/3, its pin 3 outputs high level again which makes VT disconnected and EL is off.



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