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.
This configuration of the 1980s uses NAND A-type CMOS ports, which have a linear response with...
This circuit from Delta Products was published in the May 1974 Radio Electronics magazine. The...
This encrypted key was found in a 1989 documentation. It controls a relay that is activated only...