This old voice circuit suitable for telephones of the time was found in a Radio Electronics from September 1973. The circuit is powered by a voltage of 7 V.
We found this receiver circuit for modulated light in a 90s Popular Electronics. Equivalent audio...
This field strength meter circuit was found in the March 1968 Radio Electronics magazine. The...
I found this circuit in a 1998 publication, but as all components are common, it can be easily...