telephone ringer light

  1. guclusat

    Telephone Ringer Light

    Note: U1, a 4N35 opto-coupler, isolates the telephone circuit, from the 120VAC line circuit. J1 is an RJ11 modular telephone jack. The center-most two pins are to be tapped on this RJ11 jack. If wires come out of it, they are colored red and green, by convention.