This power source was found in a Motorola manual from 1968. Transistors are from the era, and current equivalents can be used.
This circuit was found in Linear Technology documentation from the 90's. The circuit uses...
This different audio amplifier was found in a 90's Electronic Design. The circuit uses components...
This circuit of a 1991 PE Hobbyst Handbook allows the brightness of the incandescent lamp to be...