This circuit uses a 555 timer as the bases of the touch switch. You can learn more about 555 Timer after done this project. When the plate is touched the 555 timer is triggered and the output on pin 3 goes high turning on the LED and the buzzer for a certain period of time.
That time the LED and the buzzer is on is based on the values of the capacitor and resistor connected to pin 6 & 7. The 10M resistor on pin 2 causes the circuit to be very sensitive to the touch.
· 555 Timer IC
· Resistors = 470 ohm, 100k, 10M
· Capacitor = 10uf 16v
· BZ = Buzzer
· 9volt Battery + battery cap
This circuit you can use as a security purpose, attached with your padlock and switch on circuit switch, when somebody will touch your lock then buzzer will beep and LED will glow.