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.
Published in 1988 in Hands On Electronics, this circuit converts the 12 V of a battery into 120 V AC...
The current accross the LED as function of the resistor value is given by the formulas. The...
This circuit was found in an old 1980s valve documentation. The circuit can directly replace a...