This commercial earphone receiver was manufactured in the 1960s in Japan. It was powered by a 9 V battery and the transistors were made of germanium.
This 70 kHz oscillator is used to erase tapes in pre-recording. The circuit is from 1968 General...
We found this circuit in an old documentation for hams. In it we have the way to use a varicap to...
This sensitive touch circuit that triggers an oscillator uses only transistors. The circuit is...