This circuit was found in a 1980s documentation. Similar configurations appear in the section, but from different sources. The circuit makes use of components of the time.
This circuit was found in the September 1974 issue of Radio Electronics magazine. The circuit uses...
This circuit was found in the December 1983 issue of Radio Electronics magazine. The sensor is an...
We found this circuit in a 1975 publication. The circuit can be made with more modern equivalent...