555 reading-newsstand automatic floodlight circuit

Published:2011/6/13 20:25:00 Author:TaoXi | Keyword: NE555, automatic, floodlight | From:SeekIC

As the figure 17-25 shows, the automatic floodlight circuit is composed of the optoelectronic multiplex switch circuit, the oscillation clock generator and the timer control circuit.etc. The 555 offset voltage network is composed of the photodetector and the RP1. In the daytime, the photodetector has the low resistance, the electric potential of 555's pin-5 is higher than 2/3VDD threshold level, the circuit resets, pin-3 has the low level voltage, J failure to actuate, At night, the photodetector has the high resistance, pin-2's electrical level is lower than 1/3VDD, 555 sets, pin-3 has high level voltage, J closes and the light turns on. The timing power-off circuit is composed of the IC2～IC4 and the VT. The ultra-low frequency astable multivibrator is composed of the IC2(555) and R3，R4，R5.



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