A simple door handle touch alarm circuit

This is a door handle touch alarm for home security purposes. When someone touches the metal door handle, the alarm will be activated. This circuit is not suitable for full metal doors.

The power supply of this door touch alarm is 3VDC. Two AA batteries can be used to operate this circuit, making this circuit portable. Since the power consumed by this circuit is very small, the batteries can last for a long time. A variable resistor is used to adjust the touch sensitivity.

Before assembling this circuit please read some of the notes on the schematic and image diagram above.