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.
August 2017 - New DTMOS Super Junction MOSFETS from Toshiba are in stock at Mouser Electronics....
In the figure we have the configuration of the circuit as a conventional Darlington. In this...
This circuit is from the 80's documentation. The integrated circuit is from the time but can be...