This assembly is from 1957 from a Raytheon manual, but can be modernized using a BC548, 6 V power supply and common 100 mA relays.
The sensor of this circuit consists of two 1N4148 diodes connected in series. The accuracy of the...
This setting appears elsewhere on this site. This was obtained from an 80's Circuit Encyclopedia and...
This circuit can be used as a direct optical link or by optical fibers. We found it in a...