Patent GB-185674-A (GB)
Abstract: 185,674. Siemens Bros., & Co., Ltd., and Berry, J. Nov. 4, 1921. Impulse-transmitters.-In a keyboard impulsetransmitter having a relay associated with each key, the depression of key 5, for example, causes the energization of relays corresponding to keys 6, 7 - - 0 and initiates the transmission of impulses, and relays corresponding to keys 5, 4 - - 1 are then energized one by one with the impulses sent out, after which all the relays are released and impulse transmission is stopped. Figs. 1 and 2 placed side by side chow a four-digit transmitter, the operator depressing a key in each bank associated with sets of relays M, C, T, U. Certain of the thousands keys however are reserved for the transmission of single-digit and two-digit numbers. Assuming for example that the operator has depressed the key 2 in each set, the relay 3M in the set M is energized from the battery-wire 18, over its winding b, key 2 to the earth wire 17, closing a locking circuit for itself over the front contact 3m2 and back contacts 2m1, 1m1 of the relays 2M, 1M to earth,. and closing at contacts 3m1, 3m3 an energizing circuit for the winding b of the relay 4M through a wire 19. The relay 4M locks itself and closes a circuit for the relay 5M, and so on until the relay OM is energized, closing a circuit for a relay MD from earth wire 17, contact 9m1, contact 0m3, wire 20, winding of the relay MD, contact 1md1 of a relay 1MD to battery wire 18. The relay MD locks itself at the contact md1, prepare:! a circuit for the winding b of the relay 1M at the contact md2, and closes the contact md3, which has a control function in the sending out of impulses. The action in the sets C. T and U is similar, resulting in the energization of the relays CD, TD and UD, preparing circuits for the relays IC, IT and IU and closing the contacts cd3, td3 and ud3, the last contact completing the circuit of the impulse relay A through an interrupter I and earthed battery 26, impulses being sent out over the contact a2. At the first energization of the relay A, a condenser 25 is charged over a circuit from battery 26, condenser 25, front contact a1, back contacts 1u3, 1t3, 1c3 and 1m3 to earth at 31, and upon deenergization, discharges over a circuit from battery, condenser, back contact a1, front contact md3 to the common wire 33, thence over the contact 3m5 of the energized relay 3M and the contact 2m4 and the winding a of the de-energized relay 2M to the common wire 18. The relay 2M locks itself at the contact 2m2, opens its energizing circuit at the contact 2m4 and prepares at the contact 2m5 a circuit for the relay 1M, which is energized at the next condenser discharge, and locks itself at the contact 1m1 over the contact md2, breaks the condenser charging circuit at the contact 1m3 and closes the impulse circuit by bridging the contact a2 at the contact 1m4. The change over of the contact 1m1 releases the relays 2M, 3M - - 0M in turn, the relay MD being released simultaneously with the relay OM, thereby releasing the relay 1M and, by the change over of the contact md3, transferring the condenser discharge circuit from the common wire 33 of the set M to the common wire 37 of the set C, for the sending of the second digit impulses. The operations for the C, T and U sets are similar to those for the M set. A single digit is transmitted by special keys of the thousands set, for example 7, 9, 0, which are joined to the earth wire 17 through the winding b of the relay 1MD, so that this relay is energized in addition to the relay MD, closing the impulse relay circuit through the contacts 1md4, md4. A special key of the thousands set is reserved for the transmission of a pair of digits. On depression of this key, for example 8, the relay 9M is energized in the usual manner, but upon release of the key, the holding circuit includes the winding b of a relay 2MD, which is thereby energized, preparing a holding circuit for itself at the contact 2md1 and a circuit for the impulse relay at the contact 2md2, which is completed at the contact cd4 upon energization of the relay CD following the depression of any hundreds key. The contact cd4 also establishes a holding circuit for the relay 2MD through its winding a.