. Bell telephone magazine . Enclosed Glass Jar Storage Batteries in the Washington, D. C, Georgl.\Dial Office. The Space at the Bottom of the Racks Is Reserved for FutureBattery Wood Tank Batteries for the Washington, D. C, District-Metropolitan-Xa- tional Di.^l Offices TELEPHONE POWER PLANTS Today, telephone power plants make use of 20 cycle, 135cycle and 1000 cycle alternating current for signaling purposes; volt, 16 volt, 24 volt, 38 volt and 48 volt direct current fortalking and signaling; 110 volt positive and 110 volt negativedirect current for prepayment coin box operatio
. Bell telephone magazine . Enclosed Glass Jar Storage Batteries in the Washington, D. C, Georgl.\Dial Office. The Space at the Bottom of the Racks Is Reserved for FutureBattery Wood Tank Batteries for the Washington, D. C, District-Metropolitan-Xa- tional Di.^l Offices TELEPHONE POWER PLANTS Today, telephone power plants make use of 20 cycle, 135cycle and 1000 cycle alternating current for signaling purposes; volt, 16 volt, 24 volt, 38 volt and 48 volt direct current fortalking and signaling; 110 volt positive and 110 volt negativedirect current for prepayment coin box operation; and 24 volt,48 volt and 130 volt direct current for telephone repeaters,teletypewriters and direct current telegraph. In addition,various tones are used to represent audibly certain existingtelephone circuit conditions to the telephone users and to theoperators. Direct current for talking and signaling is generally furnishedfrom storage batteries; alternating; current, coin control currentand tones by motor generators. In central offices where thevolume of traffic is not sufficient to justify the generally usedsources of supply, other sources more economical, such as drycell oper
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Keywords: ., bookauthoramerican, bookcentury1900, bookdecade1920, bookyear1922
