Miller, Kempster Blanchard, 1870-1933 · New York : McGraw publishing company · leaf 584
st. It may be said in general that the dynamotor is not anefficient machine for any but ringing purposes in a telephone ex-change under any conditions. When used for charging muchtrouble is had due to inefficient regulation. The fact that a singlefield serves for both the generator and the motor… … FIG. 403.-SMALL DYNAMOTOR FOR RINGER. these machines become the most available fdr driving the busy-backand tone-test attachment already referred to in connection with Fig.397. A dynamotor for ringing purposes adapted to be driven bydirect current is shown in Fig. 404, and this has permanently…
Telephone
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