476,127. Automatic exchange systems. GENERAL ELECTRIC CO., Ltd., and COLLYER, J. E. July 29, 1936, No. 20996. [Class 40 (iv)] In a substation or operator's circuit provided with keys for transmitting a limited number of multi - digit numbers corresponding to frequently-wanted subscribers, a step-by-step switch PS is set to a position corresponding to a depressed key to effect markings in a bank of a second step-by-step switch DS producing impulses under the control of a relay having a vibrating reed-type armature, the switch DS being stopped at each marked position to provide the inter-digital pauses. For example, to transmit the number 375, the third, tenth, and fifteenth contacts are marked. When key 1 is operated, relay S energizes connecting selfinterrupting magnet PS to wiper PS1, and the switch PS hunts until the contact from which earth has been removed by the operation of the key is reached. Relay K then operates and on the release of key 1 the vibrating armature MW of relay M transmits impulses to magnet DS and over the subscriber's line. When the first marked contact is'reached, relay P operates over wiper PS2, cross-connecting frame TP, and wiper DS2 to hold relay M and energize relay PA. Relay P releases relay C which in turn releases P and an inter-digital pause is provided by the time of relapse of relays C and P. Impulsing then continues, the second digit being terminated by operation of P over wiper PS3. After the third digit, relay T operates over wiper PS4, short-circuiting the impulse contacts and completing a homing circuit over wiper DS1 for switch DS. A lamp EL is lit during impulse transmission to warn the subscriber or operator not to press any further key.
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