Apparatus for connecting and disconnecting a ringing signal to a called subscriber

Abstract From the Canadian patent

The present invention relates to an apparatus for sending a ringing signal to a called subscriber. Connection and disconnection of the signal takes place with the aid of the apparatus. The problem solved by the invention is that of current transients being generated on disconnection of the signal these transients causing a disturbing clicking noise in the engaged telephone of a subscriber in a neighbouring channel. The apparatus solving the problem includes a two-way switching circuit connected in series with an AC voltage generator, said circuit disconnecting the AC voltage to a bell when the current through the bell has its zero crossing and a discharge circuit for discharging the bell …