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 converts pulse frequency to current, which is indicated on an analog instrument. The...
Found in an Electronic Engineering from the 80's, this circuit makes use of components of the...
With the configuration shown in the figure, a common 12 V lamp lights up when light no longer...