This circuit from the 60's uses germanium transistors of the time. Listening is done on high impedance headphones.
An electric wind flow obtained by the corona effect can be obtained with this circuit from Radio...
This simple circuit found in a 1968 EEE was intended for data transmission over the telephone...
This very simple circuit was found in a 1977 documentation. The L1 coil has 3 turns of AWG wire 22 to...