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 was obtained in a 1965 American magazine translation. The coil is formed by 40 + 40...
We found this circuit in a 1991 publication. What it does is to amplify a signal with unit gain...
This is the traditional configuration of a 6 or 12 V source with 7806 or 7812 integrated circuits, for a...