This oscillator with emitter follower was found in an American documentation from the 80's. The circuit generates 100 MHz signals and the transistors admit modern equivalents.
This small earphone amplifier with germanium transistors was obtained in a Japanese publication from...
The sensor for this circuit is a phototransistor. We found it in the April 1971 issue of Radio...
Found in a 90s Popular Electronics, this circuit allows to select the operating ranges between...