This commercial transistor radio was manufactured by RCA in the 1960s. The circuit has only 4 transistors and is powered by a voltage of 9 V with an audio power of 20mW.
This circuit can work with almost any JFET. The circuit is from an Electronics Now from April...
This physical line servo control uses components that are not currently common. The circuit is from...
This circuit was found in a British documentation from 1969. It can be implemented with modern...