This circuit is for traditional old-style telephone lines found in an American 1980s documentation. Components are common and the optical coupler can be replaced with an equivalent.
Placed inside the refrigerator, this circuit triggers an oscillator when the part is opened...
In this oscillator a phase shift network formed by C1, C2, C3 and R1, R3, R4 determine the fase...
The circuit in the Multisim Blue simulation sources a regulated voltage to loads up to 50 mA. The...