Switch lighting (CB7965E)

This circuit keeps an LED on briefly when S1 is pressed. The time depends on C1. The circuit is from a Popular Electronics from the 90s.

Temperature interface (CB20543E)
This temperature sensor shield or interface was found in a PC English documentation from 1996....
Balanced Microphone Amplifier (CB4938E)
This circuit can use common operational amplifiers according to the supply voltage. One suggestion...
XTAL Oscillator up to 14 MHz (CB25535E)
This oscillator with the 4049 can generate signals up to about 14 MHz according to the article in the...