Monarch Receiver

The receiver of the Automatic Electric Company just discu ed employs but a single electromagnet by which the initial magnetization of the cores and also the variable magnetization nece ary for speech reproduction is secured. The problem of the direct-current receiver has been attacked in another way by Ernest E. Yaxley, of the Monarch Telephone Manufacturing Company, with the result shown in Fig. 54. The construction in this case is not unlike that of an ordinary permanent-magnet receiver, except that in the place of the permanent magnets two soft iron cores 1-1 are employed. On these are wound two long bobbins of insulated wire so that the direct current flowing over the telephone line will pa through these and magnetize the cores to the same degree and for the same purpose as in the case of permanent magnets. These soft iron magnet cores 1-1 continue to a point near the coil chamber, where they join the two soft iron pole pieces 2-2 , upon which the ordinary voice-current coils are wound. The two long coils 4-4 , which may be termed the direct-current coils, are of somewhat lower resistance than the two voice-current coils 3-3 . They are, however, by virtue of their greater number of turns and the greater amount of iron that is included in their cores, of much higher impedance than the voice-current coils 3-3 . These two sets of coils 4-4 and 3-3 are connected in multiple. As a result of their lower ohmic resistance the coils 4-4 will take a greater amount of the steady current which comes over the line, and therefore the greater proportion of the steady current will be employed in magnetizing the bar magnets. On account of their higher impedance to alternating currents, however, nearly all of the voice currents which are superposed on the steady currents, flowing in the line will pa through the voice-current coils 3-3 , and, being near the diaphragm, these currents will so vary the steady magnetism in the cores 2-2 as to produce the nece ary vibration of the diaphragm. IMG:384091999325875926_fig054_t.gif.png:Illustration_ Fig. 54. Monarch Direct-Current Receiver Fig. 54. Monarch Direct-Current Receiver View full size illustration. This receiver, like the one of the Automatic Electric Company, does not rely on the shell in any respect to maintain the permanency of relation between the pole pieces and the diaphragm. The cup 5 , which is of pre ed bra , contains the voice-current coils and also acts as a seat for the diaphragm. The entire working parts of this receiver may be removed by merely unscrewing the ear piece from the hard rubber shell, thus permitting the whole works to be withdrawn in an obvious manner.