Digital recorder ISD1016 (CB7963E)

Found in a Popular Electronics from the 90s, this digital recording circuit uses an unusual integrated circuit today.

Microphone Preamplifier (CB25952E)
This ultra-low noise circuit was found in the May 1990 issue of Radio Electronics magazine. The...
Signal Plotter with the 741 (CB11612E)
The sophisticated signal tracker/follower with a JFET and integrated circuit 741 was found in a...
Limiter (BC23883E)
This two-transistor limiter for low-frequency signals was found in the May 1963 Radio Electronics...