TOUCH SENSITIVE SWITCH

This circuit works on the toggle mode through finger touch. For each touch on the touch plate, either the buzzer beeps or stops.

IC1 is used as a short duration Monostable using the timing components R1 and C1. The trigger pin 2 of the timer IC555 is connected to the touch plate. So normally, the output of IC1 is low. When the touch plate is touched with the finger, IC1 triggers and gives a short pulse to the input of IC2. CD 4017 is the Johnson decade counter IC with 10 outputs. Each output goes high with a positive pulse in its input pin 14. Here IC2 is wired as a toggle switch by shorting the third output pin 4 to the reset pin 15. So the outputs 2 and 3 of IC2 turns On / Off with each pulse in its input pin 14.

Either LED or Buzzer can be used to demonstrate the toggle function of IC2.

Note : Use a jumper wire ( trimmed lead of resistor) above 1K and 10K .Use 9 volt adapter to power the circuit so that the AC hum will easily trigger the circuit. With battery, the working will not be accurate.

Note

If component removal is required for re assembling, do not bend the excess leads of components before soldering. Cut the excess lead close to the PCB and apply some flux. Apply little solder at the contact point. Do not apply, excess solder or over heat the solder points. PCB tracks will detach. Clean the surface with kerosene, or PCB cleaning fluid to remove flux and dirt.