Found in a 1966 documentation, this “coin finder” uses components from the era operating at 2.1 MHz. The circuit uses an audio amplifier for detection.
This source can supply currents up to 1 A. The circuit is from Motorola's 1993 Linear Interface ICs....
The purpose of this receiver is to monitor the signal from a nearby transmitter. It was published in an...
In the figure we have a symmetrical power supply stabilized by a zener diode. Transformer and...