The circuits below light a 20 watt lamp when the contacts are touched and the skin resistance is about 2 Megs or less. The circuit on the left uses a power MOSFET which turns on when the voltage between the source and gate is around 6 volts. The gate of the MOSFET draws no current so the voltage on the gate will be half the supply voltage or 6 volts when the resistance across the touch contacts is equal to the fixed resistance (2 Megs) between the source and gate.
The circuit on the right uses three bipolar transistors to accomplish the same result with the touch contact referenced to the negative or ground end of the supply. Since the base of a bipolar transistor draws current and the current gain is usually less than 200, three transistors are needed to raise the microamp current level through the touch contacts to a couple amps needed by the light. For additional current, the lamp could be replaced with a 12 volt relay and diode across the coil.
SK34 IC
Merkur Tint Gold Plated Stainless Steel - Titanium Arts
ReplyDeleteMerkur Tint Gold Plated Stainless Steel One of the best titanium tube razors of all time. The Merkur Classic is a titanium key ring great adjustable safety titanium cartilage earrings razor for an open tooth comb titanium ore terraria Rating: 4.3 · 13 reviews · $45.95 how to get titanium white octane · In stock