This circuit is from a Mallory 1968’s documentation. The integrated circuit is of the time and the transistor admits equivalents.
This filter was found in old Raytheon documentation. The circuit makes use of operationals of the time, but...
March 2017 - Mouser Electronics already has the new Toshiba TLP3306 photo-relay and optical...
This circuit was suggested by Popular Electronics from the 90s. The circuit is quite simple using...