. American telephone practice . standard Stromberg-Carlson desk stand, in whichthe induction coil is carried in the base of the stand. In Fig. 125 is shown a different arrangement, wherein the induc-tion coil is mounted on the connecting rack, and the ringer isenclosed in the generator box. This cut shows the standardKellogg desk stand. In Figs. 126 and 127 are shown respectively the circuits of seriesand bridging desk sets, the apparatus being so arranged that theinduction coil, generator and bell are all within a single box, bind- LOCAL BATTERY SUB-STATION EQUIPMENTS. 147 ing posts on the ba
. American telephone practice . standard Stromberg-Carlson desk stand, in whichthe induction coil is carried in the base of the stand. In Fig. 125 is shown a different arrangement, wherein the induc-tion coil is mounted on the connecting rack, and the ringer isenclosed in the generator box. This cut shows the standardKellogg desk stand. In Figs. 126 and 127 are shown respectively the circuits of seriesand bridging desk sets, the apparatus being so arranged that theinduction coil, generator and bell are all within a single box, bind- LOCAL BATTERY SUB-STATION EQUIPMENTS. 147 ing posts on the base of this box serving as terminals for theattachment of the flexible cord leading to the desk stand proper, aswell as the battery terminals and the line terminals. In this case,which is probably the simplest of all magneto desk set arrange-ments, a four-conductor cord from the desk stand to the generatorbox is required for the series set, a three-conductor cord servingfor the bridging instrument. Besides this the only external. FIG. 123.—TYPICAL DESK STAND. wiring necessary is that from the line and the battery to the postson the base of the box. In Figs. 128 and 129 are shown similarcircuits for series and bridging instruments respectively, the differ-ence in this case being that a separate connecting rack is employedupon which the induction coil is mounted, the magneto box in thiscase containing only the generator and the call bell. In these athree or four-strand flexible cord is needed from the connecting rackto the desk stand; two wires lead from the connecting: rack to the 148 AMERICAN TELEPHONE PRACTICE. bell box, two from the connecting rack to the battery and two fromthe connecting rack to the line. This arrangement is advantageous
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