Maker Factory ELECTRONICS EXPERIMENTS BOX Manual page 289

Circuit 116 and 117: The FET transistor (T1 in the circuit) has a very high input resistance. Thus the very low
conductivity of human skin is enough to turn on the transistor when the sensor surfaces are touched with a
finger.
Fig. 3.116: Circuit 116 – On button
with sensor
Fig. 3.117: Circuit
117 – Off button
with sensor
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