This circuit was obtained in the 1990 Motorola Linear Databook. The circuit uses a 139 series comparator, but other series can be used. The power source need not be symmetric.
The basic idea of this circuit is to convert the indication of a magnetic sensor to an audio tone...
This untuned circuit uses one of the world's first commercial transistors, the CK722, having been...
We found this circuit in the May 1989 issue of Radio Electronics magazine. The circuit uses...