This vibration detector motion) is constructed using bipolar transistors and consumes only 0.3 mA in standby.
This vibration detector (motion) is based on a very simple principle: a few millimeters above the relay coil (whose contacts are used) is a magnet suspended by a thin wire of 20 to 30 mm long. Any movement (vibration) of the protected object will cause an imbalance of the magnet which in turn will produce a change in the magnetic field around the coil relay (inducing a variable low voltage in the coil).
Slight change in voltage induced in coil is appreciably enhanced T1 because capacitor C1 prevents automatic adjustment.
Detection itself is made of T4, which opens when the voltage variations of the amplifier (after going through C4), reaching a level of 0.6 V. When C5 is discharged, T5 is open and this will meke T6 to conduct. In turn, it will act a buzzer connected to T6 collector