This circuit was originally intended for reading movie soundtracks. The circuit is from 1967 and was found in an English publication. The sensor is semiconductor type.
This circuit was found in an EDN from the 90s. For the components indicated, the frequency is 10 kHz....
This circuit provides voltages and a 1 kHz signal for measurement bridges. The circuit is from...
We found this circuit in an old documentation, but it is still current. General purpose...