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.
This circuit was found in Motorola documentation from 1968. SCRs can be modern equivalents and the...
This circuit was found in a 1980s telecommunications publication. The circuit uses a diode bridge to...
Suggested by General Electric in a 1967 documentation, this circuit replaces the Thryraton tubes used at...