Lie Detector (T1534E)

This circuit was found in a Popular Electronics from December 1956. Power is provided by batteries.

High Q Filter (CB25362E)
This 1/2 hertz high selectivity filter was found in the December 1990 issue of Radio Electronics...
Two Current Boosters for Stepper Motor Controls (CB11598E)
The two power steps below are intended for use with the SAA1027 stepper motor control but can be...
Mexican Siren (CB17515E)
This interesting circuit, found in a 1986 publication, includes a powerful audio amplifier. Being...