Multi-channel laser burglar alarm circuit

Published:2013/2/17 21:00:00 Author:Ecco | Keyword: Multi-channel laser, burglar alarm | From:SeekIC

VT1, VT2, RL1, RP1, R1, K and VD6 constitute light control switch, in the daytime, photoresistor RL1 is in a low resistance state, VT1 gets saturated conduction, VT2 is turned off, K relay is not energized, normally open contact J is in a disconnected state, the alarm circuit does not work; at night, RL1 becomes high impedance, VT1 is deadline, VT2 gets saturated conduction, K gets electrical to make J pull in, then the circuit supplies for the whole machine, red light-emitting diode is lit.



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