Mini Megaphone (CB8952E)

Found in Popular Electronics' 90s, this small megaphone is based on LM386. The circuit uses a high impedance microphone.

Regenerative switch for relay (CB24083E)
This circuit accelerates the tripping of a relay when energized. The circuit uses the CA3018...
Variable Reluctance Sensor Amplifier (CB14215E)
The circuit shown is from the National Semiconductor 1994 Linear Applications Handbook. The base...
FET Colpitts Oscillator (CB22394E)
This ultra-simple circuit has the frequency determined by the LC network. Any general purpose JFET...