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.
This circuit using components that are still common in our market was found in a 1987...
This circuit was obtained in a 1998 publication, but it can be easily assembled. The circuit...
Found in a 73 magazine for radio amateurs of the 90s, this circuit provides a 2 kV voltage with 7.5...