This commercial circuit is from a Japanese magazine from 1967. It uses germanium transistors, and the coil can be made with 80 to 100 turns of fine enameled wire on a ferrite rod.
These integrated ones consist of class B amplifiers with gain fixed 24 internally for better...
Found in a 1967 publication by General Electric, this control is intended for motors up to 2 A...
Found in RCA documentation from the 90s, this bass and treble control uses an operational...