. American telephone practice . B and D, to the other elec-trode, G. Vibrations of the diaphragm cause variations in theintimacy of contact between the eight points of support of the fourrods, and thus produce the desired fluctuations in resistance. It isseen that this is merely a modification of the Hughes microphone,the principles being the same, but the multiple contact allows agreater current to pass through the transmitter, and at the sametime produce greater changes in this current than in the originalform, where a single pencil was used. Moreover, the liability ofrattling is greatly red
. American telephone practice . B and D, to the other elec-trode, G. Vibrations of the diaphragm cause variations in theintimacy of contact between the eight points of support of the fourrods, and thus produce the desired fluctuations in resistance. It isseen that this is merely a modification of the Hughes microphone,the principles being the same, but the multiple contact allows agreater current to pass through the transmitter, and at the sametime produce greater changes in this current than in the originalform, where a single pencil was used. Moreover, the liability ofrattling is greatly reduced. Fig. 42 shows the Turnbull transmitter, which has been used to 58 AMERICAN TELEPHONE PRACTICE. a limited extent in this country, even until recently. In this figure,A is the diaphragm of thin wood, on the back of which is mountedthe bracket, B. Pivoted on a rod, b, carried by this bracket, areseveral carbon rods or pendants, a, which rest at their lower endagainst a carbon rod, c, carried on a bracket, C, also mounted on. FIG. 42.—THE TURNBULL TRANSMITTER. the diaphragm. The rods, b and C, form the terminals of the trans-mitter, and the current passes from one of them through the carbonpendants in multiple to the other. The variations in resistanceoccur principally in the contacts between the rod, C, and the pen-dants, a, although there is an additional effect between the pendantsand the supporting rod, b, particularly if this rod is made of carbon.
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Keywords: ., boo, bookcentury1900, bookdecade1900, bookidamericantelepho00mill
