. Automatic telephony; a comprehensive treatise on automatic and semi-automatic systems . 3?0 TRUNKS IOO TRUNKS IOO TRUWI- <S 320 SWS. IOO FIRST IOO SECOND-SELECTORSWITCHES OF-32 EACH 320 ^TRUNKS IOO TRUNI <S IOO TRUNKS 3eo secdV. LINE IOO|ROUt=SOF32 EACH IOO FIRSTSELECTORSWITCHES OOSECONOSELECTORSWITCHES Fig. 77. -Diagram illustrating scheme of using secondary lineswitches to reduce first andsecond selectors. of ten. The application of this mechanism makes it possible to give alarge number of primary lineswitches (say 2000) access to a group of 100first selectors. The d
. Automatic telephony; a comprehensive treatise on automatic and semi-automatic systems . 3?0 TRUNKS IOO TRUNKS IOO TRUWI- <S 320 SWS. IOO FIRST IOO SECOND-SELECTORSWITCHES OF-32 EACH 320 ^TRUNKS IOO TRUNI <S IOO TRUNKS 3eo secdV. LINE IOO|ROUt=SOF32 EACH IOO FIRSTSELECTORSWITCHES OOSECONOSELECTORSWITCHES Fig. 77. -Diagram illustrating scheme of using secondary lineswitches to reduce first andsecond selectors. of ten. The application of this mechanism makes it possible to give alarge number of primary lineswitches (say 2000) access to a group of 100first selectors. The drawing in Fig. 77 shows the number of primary lineswitches, thenumber of primary lineswiteh groups, the number of trunks from primary AUTOMATIC ELECTRIC COMPANYS APPARATUS 85 lineswitches to secondary lineswitches, the number of secondary lino-switch sections, the number of trunks from secondary lineswitches to firstselectors, and from first to second selectors, that might be used in a typicaloffice of 4000 lines, using third selector Sometimes secondary lineswitches are used to reduce trunks betweenmain offices, and they are then generally placed between the first selectorswitches and the repeaters on the outgoing trunks. When the secondaryswitches are inserted between the lineswitches and the first selectors, thecircuit is such that when a subscriber lifts his receiver from the switch-hook, preparatory to making a call, his primary lineswitch and the second- 86 AUTOMATIC TELEPHONY ary lineswitch to which it connects him operate almost in unison, so thatthe first selector secured is operated by the first motion of the dial asusual. Figure 78 shows a circuit from a calling telephone through a primaryand secondary lineswitch to a first selector trunk. The circuits of the secondary lineswitch may be divided into thefollowing parts: secondary lineswitch proper, master switch, and relayequipment. The trunk from the primary to the secondary lineswitchconsists of four wire
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Keywords: ., bookcentury1900, bookdecade1920, booksubjecttelephone, bookyear19
