This balance control for the channels of a stereo system was found in a 1969 Mullard documentation. The transistors may be the modern BC548 equivalents.
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...