This circuit is from a Radio Electronics from March 1970. The integrated circuit used is one of the first for this purpose, being improved later leading to types that succeeded it.
This small preamp for low impedance microphones was found in a Popular Electronics from November 1968....
The CA3162E and CA3161E pair were widely used to create a 3-digit digital display. This basic...
This circuit, which uses common components even today, was found in a 2001 documentation. It is an...