Camera-alarm-trigger

  
Transistor Ql remains off until the magnetic switch connected to Jl closes. When that happens, the 9 Vis connected through Rl to Ql`S base. Ql turns on, thereby charging C2 through relay Kl, which causes Kl `s contacts to close. Since the contacts connect viaJ2 to the remote control jack in the camera, which in tum connects to the camera`s shutter release, the closure of Kl`s contacts will cause the camera`s shutter to trigger. After C2 charges, Kl opens because current through its coil ceases; the camera won`t take another picture.
Camera-alarm-trigger - schematic

If Ql turns off because the magnetic switch on the window or gate opens, C2 discharges and the circuit is ready for another cycle. As long as Ql remains on, C2 stays charged and prevents Kl from triggering more photos. Capacitor Cl bypasses spurious magnetic switch noises from physical phenomena, such as a rattling window or a gate shaking in the wind, thus reducing the likelihood of an unwanted picture. Resistor R2 biases Ql and dampens Kl/C2 oscillations which might cause contact bounce. Diode Dl prevents C2 from discharging through Kl; the relay coil isn"t polarity conscious and C2 discharging through it would trigger an unwanted picture.




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