Patent GB-163807-A (GB)
Abstract: 163,807. Automatic Telephone Manufacturing Co., Ltd., (Automatic Electric Co.). Feb. 26, 1920. Order apparatus.-Relates to call-indicators for indicating the number of a wanted telephone line. In the system described, an idle junction line leading from an automatic exchange to a manual exchange and selected by the first digit dialled bv a calling subscriber, terminates in a cord circuit, having asssociated therewith an automatic switch adapted to select an idle register set R<1>, R<2>, R<3>, R<4>, Figs. 2 and 3, to store the number of the wanted manual subscriber. A single lamp indicator V, Fig. 4, is provided at the operator's position, to which if idle the registered call is at once transferred. By a series arrangement between successive contacts of the testing relays 304, 300<1>, &c. of all the register sets, the stored calls are transferred one at a time to the indicator, preference being given to the call stored in the lowest register. The provision of a special set of keys K<2> - - K<6>, allows the operator to cut in and cause the indication of any call unduly held up. A timing device P is associated with each register set, whereby if the number of digits in the subscriber's number may vary, as in the case of the last digit being allotted for party line work, when a number is registered which contains less than the maximum number of digits, it is transferred to the indicator (if idle) after a definite time interval. Operation of register by numerical impulses. The second series of impulses sent by the calling subscriber de-energizes the line relay and causes corresponding interruptions in the circuit of the relay 203, which at its armature 221 completes the operating circuit of the first register switch R<1>, the wipers of which are rotated an appropriate number of steps. As soon as the wiper 307 arrives at the first contact, the offnormal relay 301 responds, prepares a circuit for the release magnet 305, and, on the relapse of the relay 302, transfers the operating circuit to the relay 361 and stepping-magnet 364 of the second switch R<2>, which is stepped round in accordance with the impulses of the third digit, and transfers the operating circuit to the third switch R<3> as in the case of the switch R<1> previously operated. The switch R<3> is now set in accordance with the fourth digit, and in addition to transferring the operating circuit to the stepping-magnet 404 of the switch R<4>, on the relapse of the slow-acting relay 381, prepares a circuit for the stepping-magnet 433 of the timing switch P which is then rotated one step each time the clock mechanism T grounds the common conductor 435, say every half-second. The fifth or final digit is used for selectively ringing a party line and if sent is registered on the switch R<4> by the magnet 404. On leaving its normal position the wiper 417 completes a circuit for the relay 402, which at its armature 410 breaks the circuit of the stepping-magnet 433 and stops the timing switch P. On the relapse of the series relay a circuit is completed for the transfer relay 303 over conductors 419 and 328, and the lamp L<1> is illuminated to inform the operator which register set is in use. If a party line is not required, a fifth digit is not sent and the wipers 438, 437 of the switch P are rotated until after an interval of say four seconds the relay 431 is energized to disconnect the stepping-magnet 433, and a grounded potential is put on the conductors 439, 328 to energize the transfer relay 303 and light the lamp L<1>. At busy times the timing device P may be cut out by operation of a key K<7>, which earths a common conductor 332 and energizes a relay, as 441, in each register set. By this means the lamp L<1> and transfer relay 303 are operated as soon as the register switch R<3> finishes its operation. If a party line is being called the switch R<4> is operated as usual and the transfer circuit over the conductor 328 is broken at armature 407 and the lamp indicator V is extinguished, thus informing the operator that a final digit is being sent. In a modification, an additional switch is provided for controlling the register switches R<1> - - R<4>. This additional switch is rotated one step on the release of two slow-acting relays at the completion of each series of impulses, and transfers the operating circuit in succession to the switches corresponding to each digit. On the completion of the last digit it is rotated a final step to earth the conductor 328 and energize the transfer relay 303 and lamp L<1>. Transfer of the number to the lamp indicator. The lamp indicator V, Fig. 4, comprises four columns of lamps, one for each digit, adapted to be illuminated behind stencils. The lamps of each column are multipled to the appropriate contacts of all the corresponding register switches in all the register sets at the position. The number is transferred to the indicator V on the response of the testing relay 304 which at its armature 319 grounds the common strip in the bank of register R<1>, and at armature 320 causes the energization of relays 362, 382, and 400 of the other switches which also ground their common sectors and light the selected lamps to indicate the number. If several registers are waiting to transfer calls to the indicator, the lowest register set is always given preference. For instance, if the indicator V becomes idle on the release of No. 2 register, and registers Nos. 1, 3, and 4 are waiting to transfer calls, on the relapse of relays 303<1> and 304<1>, the testing relay 304 of No. 1 register is energized, a short circuit over the conductor 340 having been removed. On the release of No. 1 register the testing relays of registers Nos. 3 and 4 are simultaneously energized over the lower armatures of relays 304, but in operating, the testing relay of register No. 3 breaks the circuit of the testing relay of register No. 4. Any call unduly held up may be indicated by the operation of cut-in keys K<2> - - K<6>, located below the pilot lamps. Depression of a cut-in key disconnects earth from the conductor 321 and connects the winding of the appropriate testing relay direct to ground. In a modification, an extra bank of contacts is provided on each of the switches R<1> - - R<4>, wired to the lamps of a spare indicator. A switch is provided whereby if one indicator develops a fault the operating leads may be transferred from one bank of contacts to the other. Release of the register set. On learning the wanted number the operator inserts the plug of the cord circuit, indicated by the supervisory lamp L', into the jack J of the called subscriber. The energization of the sleeve relay 200 is followed by the energization of relay 210, which locks itself and extinguishes the lamp L<7>, whilst the consequent relapse of the switching relay 250 disconnects the line switch C<1>, and breaks the circuit of relay 300. Conductor 330 is thereby earthed and the release magnets of all the switches energize and restore the switches to normal.