Digital recorder ISD1016 (CB7963E)

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

Humidity Alarm (CB16326E)
The circuit in the figure shows that it is an oscillator driven directly by the conduction of Q1...
1 to 3 W FM transmitter (CB16653E)
Depending on the output transistor used, this transmitter can provide power from 1 to 3 W. The...
555 Timer 555 (2) (CB3983E)
The circuit presented is suggested by Mullard (Philips) in an old manual. The circuit uses a...