The two simple touch sensitive switch circuits listed below illuminate a 20 watt light bulb any time the connections are confronted so the skin resistance is mostly about a couple of Megs or lesser. The circuit on the left hand side makes use of a power MOSFET which switches on every time the voltage in between the supply and gate is approximately 6 volts. The gate of the MOSFET consumes zero current as a result the voltage on the gate is going to be fifty percent the supply voltage or six volts whenever the level of resistance around the touch leads is on par with the set resistance (2 Megs) in between the supply and mosfet gate.
The simple touch sensitive switch circuit on the right hand side takes advantage of 3 BJT to fulfill the equivalent outcome by using the touch approach referenced to the negative or ground ending of the source. Because the base of a BJT consumes current as well as the current gain is invariably below 200, several transistors combine to elevate the uamp current intensity by way of the touch contacts to a good number of amps essential to the illumination. For extra current, the light bulb could possibly be swapped with a 12 volt relay and diode parallel with the coil.