Touch switch circuit for control lamp

Touch Activated Light

 Districts among the 20 watt light bulb are touching the contacts and the resistance of the skin is about 2 MB or less. Circle on the left side to use the power MOSFET, which lights up when the voltage between the gate-source and about 6 volts. Gate MOSFET has no current so the voltage on the gate half the supply voltage, or 6 volts when the resistance across the touch contacts equal to a fixed resistance (2 MB) between the source and gate to be.
Circuit on the right uses three bipolar transistors, the same result with a touch contact links at the negative end of the country or bid away.

From the base of a bipolar transistor draws current and current gain is typically less than 200, three transistors to Microamp current level through the touch contacts for a couple of amps needed to increase light. Another stream, can replace the lamp with a 12-volt relay coil and diode.