This circuit is from a 1972 Motorola publication. The used transistor can still be found, but it can be used equivalent. The circuit is powered by the amplifier with which it must operate.
I got this circuit from an English magazine from 1977. It can still be easily assembled, as the...
This simple lie detector was found in Popular Electronics. Transistors are commonly used. The...
Found in a 1980 documentation, this circuit drives a transducer (X1) when the car battery has its...