Crystal oscillator (CB9504E)

This circuit was found in a 90s Popular Electronics. It can generate signals from 3 to 10 MHz.

SCR mechanical drive (CB6572E)
This contact or reed switch actuation was found in a 1964 Electronic Design. The circuit can be...
Simplified 2-bit decoder 7400 (CB22422E)
This is the previous version, but with a simplification given by the use of the 7404 and 7408...
Microphone Signal Conditioner (CB15601E)
In the figure we present a circuit of a microphone signal conditioner using the SSM2167 integrated...