PCB Design - Touch ON and OFF Circuit

 



Working of the Project

  • Connect the circuit as per the circuit diagram and apply the power supply.
  • To turn “ON” the device, touch the “ON” plate with your finger and to turn OFF the device , touch the OFF plate.
  • When power supply is applied to circuit, the device connected through the relay (we have connected a light bulb) remains OFF. Now, if we observe the circuit diagram, Pin 2 is pulled HIGH and Pin 6 is Pulled LOW.
  • When we touch the ON plate, voltage at Pin 2 (Trigger Pin) of the 555 IC becomes LOW. As Pin 6 is already LOW, the output at Pin 3 becomes HIGH.
  • Since this is connected to the Relay Module through the Transistor, the Transistor will be turned ON and it in turn activates the Relay. As a result, the device gets switched ON.
  • At this point voltage at pin 6 is zero as it pulled LOW by default and voltage at Pin 2 is HIGH.
  • Now, when you touch the OFF plate, the Pin 6 is supplied with +5V for a brief time and as a result, the output of the 555 Timer IC will become LOW.
  • This will turn off the transistor and also the relay. Hence, the device will be switched OFF.
  • This circuit works by turning a relay to “ON” state by pressing a button and when the button is pressed again device changes to “OFF”. It is working similar to a flip-flop.

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