This is a simple touch switch circuit built using transistor. In this circuit when a person touches the touch pad provided (or you can have simple wire instead of touch pad) at the base of the NPN transistor and also to the positive of 5V battery then his/her skin acts as a resistor and this closes the circuit and at the same time the transistor turns on and hence the LED connected there glows.
Here I have given Proteus demonstration of the same.
When no one touches the pad LED is not ON is shown below.
Here I have given Proteus demonstration of the same.
When no one touches the pad LED is not ON is shown below.
When someone touches the pad then the LED glows and is shown below.
