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.
We found this circuit in the September 1992 issue of Radio Electronics magazine. It can be...
This circuit adds an amplifying transistor that can supply loads of up to 250 mA. The circuit is...
This circuit was found in a 1964 Electronic Design. The transistor may be a current equivalent of...