Anti-theft car audio system circuit diagram

  
Anti-theft car audio system circuit is shown, which is taken from the car battery 12V DC power supply. When after closing the switch S1. Optocoupler IC1 light emitting diode is
Anti-theft car audio system circuit diagram - schematic

lit, the internal light due phototransistor conduction, IC1 outputs a high level input to the NAND gate, the NAND gate 1 output low. The low increase in NAND gate 2 input feet, is controlled by a NAND gate 2, 3 consisting of NAND gate low frequency oscillator to stop, so that the entire circuit is in waiting alert state. When the thieves cut the audio cable, since the optocoupler to the negative electrode inside the light-emitting diodes have been cut off at this time, so that IC1s feet vacant, internal light emitting diode immediately stop working, IC1 pin output low, NAND gate 1 output high, the NAND gate 2,3 consisting of a low frequency oscillator starts oscillation signal output control VT1 and intermittent relay K1: K1 normally open contact K1-1 also closed when closing time control a beeper alarm will sound a loud alarm will attract attention.




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