We found this circuit in a documentation from the 90's. The coil has its characteristics given next to the diagram. Power is provided by a 9 V battery and a range of a few tens of meters.
This circuit is used in transceivers, enabling input selection by diode switching through polarity...
This configuration was found in an American publication from the 90s. Operators admit equivalents just...
This circuit was found in an Italian magazine Elettronica Prática of 1977. The transistors can be...