GB191123500A - Improved Means of and Apparatus for Recording Calls made by Telephone. - Google Patents

Abstract

23,500. Bridge, E. H. Oct. 24. Metering systems.-Metering apparatus arranged in the exchange operator's cord circuit consists of two electro-magnets, one being energized through the calling subscriber's circuit, and the other by that of the called subscriber. When the call is effective, one of the magnets registers the call, an ineffective call being registered by the other magnet. The two magnets 8 with their switches are shown in Fig. 1 and the circuit arrangements are shown in Fig. 5. A call having been received and the corresponding plug e having been inserted, the circuit shown in heavy lines is completed over one of the windings 8<a> of the two magnets and the winding 8 of the lower magnet to ground at the plug sleeve. The lower magnet attracts its armature 9 thus tilting the ball race 15, and slightly raising the armature 10. When the called subscriber replies, a second circuit is completed from the battery b over the second winding 8a of each magnet and the winding 8 of the upper magnet to ground at the sleeve of plug f. The attraction of armature 10 causes the bent piece 13 to strike the spring 14 and project the balls 24 along the guide 25, thus closing the contact l with the spring 27. The contact registers the effective calls on the operator's meter c and subscriber's meter k. The attraction of the armature 10 also enables the loop 17 to tilt the race 15, thus returning the ball 20 without contact having been made between the springs 21, 22 ; but if the call is not answered, the removal of the plug e by de-energizing the magnet 8 closes the contact j at the springs 21, 22 and the meter d registers an ineffective call. The split wound coil 8<a> on each magnet ensures the armatures being held until both subscribers are disconnected. The coils 8, 8<a> may be used in place of the usual resistances shunting the lamps in the cord circuit.