Patent GB-191304611-A (GB)
Title: Telephone Repeater System.
Inventor: SHREEVE HERBERT EDWARD
IPC: H04B3/36
Filed: 1913-02-24
Granted: 1913-09-11
Abstract: 4611. Shreeve, H. E. Feb. 24, 1912, [Convention date]. Exchange systems; telephonic relays and repeaters. - Telephone repeating-apparatus is bridged across the conductors of a cord circuit, the bridge being completed when both plugs are inserted in jacks. The insertion of the plugs 5, 6 energizes the relays 31, 33, and a circuit is completed from the battery 34 over contacts 82, 83 of a relay 33, conductor 84, contact 40, conductor 90, relays 35, 36, and contacts 93, 95, 98 to ground. Currents from the side of the plug 5 pass on one hand over the lead 7, contacts of keys 117, 55, winding 50, and one half of winding 10 to mid-point 101, and on the other hand over lead 8, winding 51, and one half of winding 11 to mid-point 110. The points 101, 110 are bridged by a circuit over lead 108, contact 80, lead 106, winding 20 of transformer 21, and lead 103. The secondary winding 22 of the transformer 21 is in circuit with the energizing-winding 17 of the magneto-microphonic relay 15, the microphone element 16 of which is in a circuit from battery 34 contacts of relay 33, lead 84, contact 40, resistance 43, winding 12, microphone 16, magnetizing-winding 18 of relay, inductance 65 to ground. The second halves of the windings 10, 11 are in circuit with the line to the plug 6 so that the relayed currents are passed from the winding 12 to this line. The key 42 may be moved to close any of the contacts 40 or the contact 41. The contacts 40 regulate the resistance 43 in the microphone circuit, and the contact 41 controls the relay 23, which is adapted to reverse the polarity of the relay winding 17. The operator's speaking-set 53, 58 is connected by the key 54 to the conductors 150, 157 and the secondary winding 52, which is associated with the symmetrically-arranged primary windings 50, 51 so that no unbalance of the circuits is brought about by the operator. Any difference in phase of the currents on the two sides of the line is indicated by blurred receiving in the receiver 53. The operation of the listening-key 62 connects the winding 61 across the points 101, 110 through the contacts 165. The opening of contact 98 puts the repeater out of action by de-energizing the relays 35, 36. The cut-off key 55 enables the operator to talk on to the line in either direction without interfering with the third party. The ringing key 117 shortcircuits the energizing-winding 17 over the contact 190 or 191. The supervisory relay 26 is connected in shunt with the winding 20 between the points 101, 110 and is thus placed symmetrically with regard to the two sides of the line. When ringing current arrives from either side of the line the contact 181 brings the slowacting relay 27 into a circuit extending to ground over the contact 98 of the key 62. The contacts 185, 186 complete a holdon circuit for the relay and light the lamp 28 until the key 62 is operated. The impedance of the inductances 24, 26 and condenser 25 is arranged to allow the passage of ringing current without appreciably shunting the talking currents. The relay 27 is made slow-acting to prevent its operation by currents of telegraph apparatus in the line.