This high-sensitivity circuit was found in a 1980s documentation. The source can be a 9 V battery with a splitter to make it symmetrical. The shock can be 200 uH or more.
This circuit for frequencies of 20 to 2 kHz was obtained in English documentation from 1966. The...
The oscillator of this circuit operates around 8 MHz, but the output will be at a frequency three times...
This circuit with transistors of the time was found in the magazine Radio Electroinics of June of...