The circuit shown is intended to control a direct current power load with a single touch. The circuit is momentary and very sensitive because it uses a power MOSFET.
The resistance of the skin of the finger touches the sensor is sufficient to let pass the current that polarizes this circuit, causing the power transistor to drive.
The current and the maximum voltage of the load depend on the transistor used, being able to reach several amps with power up to near 30 V.
The circuit must be supplied by battery or power supply with transformer, for safety reasons.
Depending on the load, the MOSFET must be equipped with a good heat radiator.
In figure 1 we have the complete diagram of the apparatus.
Its assembly can be done on a small terminal srtrip, as shown in figure 2.
The resistors are 1/8 W and the sensor consists of two metal pads that must be played simultaneously.
Material list
Q1 - IRF640 or any power MOSFET
X1 - sensor - see text
R1- 100 k ohms - resistor - brown, black, yellow
R2 - 10 M ohms - resistor - brown, black, blue
Several:
Terminal strip, power source or battery, wires, solder, etc.
