Digital recorder ISD1016 (CB7963E)

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

Heartbeat Detector (CB25472S)
This heartbeat sensor circuit was found in the July 1992 issue of Radio Electronics magazine. The...
Power stage (CB7279E)
This amplifier circuit with a low power MOSFET was found in Popular Electronics from the 90s. The...
Versatile Astable Multivibrator (CB25329E)
This circuit, which can be built with several CMOS gates, was found in the March 1996 issue of...