Digital recorder ISD1016 (CB7963E)

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

Temperature alarm (CB22122E)
This circuit sensor is an NTC with a resistance of the order of 2k. The SCR can be from the TIC...
PNP Constant Current Source (CB1242E)
The load current can be adjusted up to about 1 A. The transistor can be TIP32 or TIP42. The...
Relaxation Oscillator (CB23592E)
This oscillator with common general-purpose transistors appeared in Radio Electronics magazine in...