water+detector+schematic

Rain alarm is a simple circuit using water sensor (transducer) that produces an audible alarm whenever rain falls. The circuit can be based on two transistors and or a NE555 IC. The two transistors are wired as a switch which goes on when the base of Q1 is shorted to the positive of the supply [...]

This detector circuit is for detecting a Lie. The lie detector circuit diagram consists of three transistors, a capacitor, two lights or LEDs, five resistors, and a variable resistor. This Lie Detector circuit is based on the fact that a person’s skin resistance changes when they sweat (sweating because they’re lying). Dry skin has a [...]