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 activates a relay producing pulses at regular intervals adjusted by the...
This source with two symmetrical output voltages was found in 90s Radio Electronics. The 22 V...
The tones of this circuit are determined by the feedback resistors on the oscillators with the...