We found this circuit in the June 1992 issue of Radio Electronics magazine. The sensor is a common diode. The circuit is powered by the power grid from a 12 V transformer.
This 300 Hz to 3.4 kHz filter was found in the May 1989 Radio Electronics magazine. The circuit...
This circuit used in signaling for boats, cars or barriers was found in a 1980s documentation. It still...
This circuit was found in a NASA documentation from the 1980s. Component values are application...