Found in an old publication, this is a transmitter with a spark coil. The high frequency oscillations of the high voltage spark generate the signal thrown at the antenna.
The circuit shown in the figure generates a rectangular signal whose frequency depends on C1. For...
This voltage regulator for low current applications (a few milliamps) is from a European...
This circuit was found in a Popular Electronics from the 90s. The circuit uses TTL technology and...