Earth quake cum anti theft alarm

Piezo sensor basically detects the vibrations.If you install inside or behind the door ,it will alarms you if someone try to break your door .Once it turn on ,it does not off until power gone.
Here R1 limits the current at the gate.gate. Bt169d is low cost scr with current 0.5A. R2 is for increase the latching current to prevent turn off scr .buzzer consumes only low current ,which is sometimes less than latching current of scr.