These optical relays, which can act as a shield, were found in an American documentation from the 1980s. The circuit has a LDR sensor. It can be adapted for other types of sensors.
For reference only, this is the first IF amplifier stage of a common transistor radio from the...
This circuit from July 1975 Radio Electronics uses any operating system with a symmetrical source....
This setting is valid for other transconductance operational amplifiers. The circuit is from...