American telegraphy and encyclopedia of the telegraph; systems, apparatus, operation (1909)
Maver, William, jr. [from old catalog] · New York, Maver publishing company · leaf 204
^ require less attention than the latter, since any variationin current strength on the line affects both poles of the polarized relay similarly,whereas in the case of continuous current working a variation in the current FIG. 138/. DOUBLE-CURRENT SINGLE-WIRE REPEATER. r r ,^J^t … ^IMr iruVc H|l[rl|lK strength makes it necessary to increase or decrease the tension of the retractile springof the Morse neutral relay. In the double-current system, for ordinary working, the apparatus iaJ set for send-ing and receiving by means of a manually operated three-point switch p, Fig.…
Telegraph
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