Simple Touch Switch Using Two Transistor

The circuit shown here is of simple touch switch which is used to control various types of electrical appliances like electrical bulb, fan, door bell etc. The complete circuit is build around two general purpose transistors, a relay and a touch plate. The length of wire connected between touch plate and base of transistor T1 must be short as possible, where size of touch plate must not exceed the size of 1 rupee coin. Transistor T1 is used as signal amplifier where T2 is a relay driver transistor.

simple touch switch circuit

PARTS LIST OD SIMPLE TOUCH SWITCH

Semiconductors
T1 = BC148 (NPN transistor)

T2 = AC128 (PNP transistor)

D1 = 1N4001 (Diode)

Miscellaneous
RL1 = 6V relay

Touch plate