Our valued clients can avail Touch Switch from us. Touch Switch makes possible to turn on/off a device by touching a metal plate successively. The circuit uses timer IC555 (IC1), which is followed by master slave JK flip- flop IC4027 (IC2). On touching the plate, IC1 gets triggered and IC2 makes output at pin1 high and low on first and second touch respectively. Accordingly relay becomes on and off successively.
About the Circuit :
When the metal plate is touched, IC1 performs one monostable operation. Output at pin3 of IC1 goes high. This pulse acts as a clock input at pin3 of IC2. When clock is high, master flip-flop of IC2 is enabled and data inputs (J and K inputs at pin5 and pin6 respectively) are not effective at this transition. When clock goes low, slave is enabled and data is transferred from master to slave.
During the first touch, output Q at pin1 of IC2 goes high. Transistor T2 conducts and relay becomes on. Now during the second touch, output Q becomes low. Because in master slave JK flip flop output changes to the complement of last state its state at successive clock pulses. Thus T2 gets cut off and relay becomes off.
The circuit also gives visual indication of touch switch using two LEDs. When Q becomes high, T1 turns ON which makes the red LED D4 turns OFF and green LED D5 glows indicates that the device is on. Similarly, when Q becomes low, T1 cuts off which makes red LED D4 to glow and green LED D5 to goes OFF. This indicates that the device becomes off.

Our valued clients can avail Touch Switch from us. Touch Switch makes possible to turn on/off a device by touching a metal plate successively. The circuit uses timer IC555 (IC1), which is followed by master slave JK flip- flop IC4027 (IC2). On touching the plate, IC1 gets triggered and IC2 makes output at pin1 high and low on first and second touch respectively. Accordingly relay becomes on and off successively.
About the Circuit :
When the metal plate is touched, IC1 performs one monostable operation. Output at pin3 of IC1 goes high. This pulse acts as a clock input at pin3 of IC2. When clock is high, master flip-flop of IC2 is enabled and data inputs (J and K inputs at pin5 and pin6 respectively) are not effective at this transition. When clock goes low, slave is enabled and data is transferred from master to slave.
During the first touch, output Q at pin1 of IC2 goes high. Transistor T2 conducts and relay becomes on. Now during the second touch, output Q becomes low. Because in master slave JK flip flop output changes to the complement of last state its state at successive clock pulses. Thus T2 gets cut off and relay becomes off.
The circuit also gives visual indication of touch switch using two LEDs. When Q becomes high, T1 turns ON which makes the red LED D4 turns OFF and green LED D5 glows indicates that the device is on. Similarly, when Q becomes low, T1 cuts off which makes red LED D4 to glow and green LED D5 to goes OFF. This indicates that the device becomes off.