Using the 555 and 4020, this timer was found in the July 1994 Radio Electronics magazine. The relay is voltage-dependent, and the transistor is general purpose.
This simple lie detector was found in Popular Electronics. Transistors are commonly used. The...
Found in the 2005 Linear Technology Application Manual, this circuit controls the torque of a...
This circuit was found in the Italian magazine Radio Elettronica from September 1977. It consists of a...