This 9 V battery eliminator was found in Radio Electronics magazine from June 1966. The transistor is of medium power and must be equipped with a small heat sink.
This circuit uses an MW radio tuned to around 540 kHz to detect atmospheric signals, for example, from...
This project was found in a 1982 publication. It is a small transmitter that can send signals from...
This circuit is from a 1960 book by Hugo Gernsback. The transistors are germanium from the time....