. American telephone practice . FIG. 403.—SMALL DYNAMOTOR FOR RINGER. these machines become the most available for driving the busy-backand tone-test attachment already referred to in connection with A dynamotor for ringing purposes adapted to be driven bydirect current is shown in Fig. 404, and this has permanently at-tached to it a busy-back of obvious construction. Until recently trouble has been experienced in applying alter-nating current motors to the direct driving of ringing reason for this was that all alternating motors available ran atsuch high speed that when
. American telephone practice . FIG. 403.—SMALL DYNAMOTOR FOR RINGER. these machines become the most available for driving the busy-backand tone-test attachment already referred to in connection with A dynamotor for ringing purposes adapted to be driven bydirect current is shown in Fig. 404, and this has permanently at-tached to it a busy-back of obvious construction. Until recently trouble has been experienced in applying alter-nating current motors to the direct driving of ringing reason for this was that all alternating motors available ran atsuch high speed that when direct-connected to ringing machinesthe frequency of the alternating current generated thereby was toogreat for properly actuating the bells. As a result of this direct-con-nected machines were not used in such cases, the ringing generator POWER PLANTS FOR COMMON BATTERY SYSTEMS. 563 being belted to an alternating current motor in such manner as torun at lower speed. A ringing machine equipped with busy-back. FIG. 404.—SMALL DYNAMOTOR WITH BUSY-BACK ATTACHMENT. and dont-answer attachment and belted to an alternating currentmotor is shown in Fig. 405, this being a set used by the Stromberg-Carlson Company in one of their exchanges. Recently the Holtzer-
Size: 1989px × 1257px
Photo credit: © Reading Room 2020 / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., boo, bookcentury1900, bookdecade1900, bookidamericantelepho00mill
