We found this circuit in a Radio Electronics from October 1963. The circuit uses an output transformer with a center tap. The trimpot is adjusted for higher gain and lower quiescent current.
This guitar sustain circuit uses only two transistors and can be powered by a 9V battery. The...
This 1989 circuit activates a protection relay if one or two phases are missing from a three-phase...
Although not using transformers, this amplifier may have difficulty mounting if the original...