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.
The time the output is high (1) of a TLCSSB in the astable configuration depends on Ra and C. The...
Found in a publication from the 60's, this power supply has no regulation, but only current...
This short-range circuit can act as a wireless microphone. We got the schematic and the printed...