Magneto-Telephone Sets

Wall. In Fig. 142 is shown a familiar type of wall set. The containing box includes within it all of the working parts of the apparatus except that which is nece arily left outside in order to be within the reach of the user. Fig. 143 shows the same set with the door open. This gives a good idea of the ordinary arrangement of the apparatus within. It is seen that the polarized bell or ringer has its working parts mounted on the inside of the door or cover of the box, the tapper projecting through so as to play between the gongs on the outside. Likewise the transmitter arm, which supports the transmitter and allows its adjustment up and down to accommodate itself to the height of the user, is mounted on the front of the door, and the conductors leading to it may be seen fastened to the rear of the door in Fig. 143. In some wall sets the wires leading to the bell and transmitter are connected to the wiring of the rest of the set through the hinges of the door, thus allowing the door to be opened and closed repeatedly without breaking off the wires. In order to always insure positive electrical contact between the stationary and movable parts of the hinge a small wire is wound around the hinge pin, one end being soldered to the stationary part and the other end to the movable part of the hinge. In other forms of wall set the wires to the bell and the transmitter lead directly from the stationary portion of the cabinet to the back of the door, the wires being left long enough to have sufficient flexibility to allow the door to be opened and closed without injuring the wires. At the upper portion of the box there is mounted the hook switch, this being, in this case, of the short lever type. The lever of the hook projects through the side of the box so as to make the hook available as a support for the receiver. Immediately at the right of the hook switch is mounted the induction coil, and immediately below this the generator, its crank handle projecting through the right-hand side of the box so as to be available for use there. The generator is usually mounted on a transverse shelf acro the middle of the cabinet, this shelf serving to form a compartment below it in which the dry battery of two or three cells is placed. The wall telephone-set cabinets have a umed a multitude of forms. When wet cells rather than dry cells were ordinarily employed, as was the case up to about the year 1895, the magneto generator, polarized bell, and hook switch were usually mounted in a rectangular box placed at the top of a long backboard. Immediately below this on the backboard was mounted the transmitter arm, and sometimes the base of this included the induction coil. Below this was the battery box, this being a large affair usually adapted to accommodate two and sometimes three ordinary LeClanché cells side by side. The dry cell has almost completely replaced the wet cell in this country, and as a result, the general type of wall set as shown in Figs. 142 and 143, has gradually replaced the old wet-cell type, which was more cumbrous and unsightly. It is usual on wall sets to provide some sort of a shelf, as indicated in Fig. 142, for the convenience of the user in making notes and memoranda. Desk. In the magneto desk-telephone sets, the so-called desk stand, containing the transmitter, the receiver, and the hook switch, with the standard upon which they are mounted, is shown in Fig. 144. This desk stand evidently does not comprise the complete equipment for a magneto desk-telephone set, since the generator, polarized bell, and battery are lacking. The generator and bell are usually mounted together in a box, either on the under side of the desk of the user or on the wall within easy reach of his chair. Connections are made between the apparatus in the desk stand proper and the battery, generator, and bell by means of flexible conducting cords, these carrying a plurality of conductors, as required by the particular circuit of the telephone in question. Such a complete magneto desk-telephone set is shown in Fig. 145, this being one of the types manufactured by the Stromberg-Carlson Manufacturing Company. IMG:384091999325875926_fig144_t.gif.png:Illustration_ Fig. 144. Desk Stand Fig. 144. Desk Stand View full size illustration. A great variety of arrangements of the various parts of magneto desk-telephone apparatus is employed in practice. Sometimes, as shown in Fig. 145, the magneto bell box is equipped with binding posts for terminating all of the conductors in the cord, the line wires also running to some of these binding posts. In the magneto-telephone set illustrated the box is made large enough to accommodate only the generator and call bell, and the batteries are mounted elsewhere, as in a drawer of the desk, while in other cases there is no other equipment but that shown in the cut, the batteries being mounted within the magneto bell box itself. In still other cases, the polarized bell is contained in one box, the generator in another, the batteries in the drawer of the desk, the induction coil being mounted either in the base of the desk stand, in the bell box, or in the generator box. In such cases all of the circuits of the various scattered parts are wired to a terminal strip, located at some convenient point, this strip containing terminals for all the wires leading from the various parts and for the line wires themselves. By combining the various wires on the terminals of this terminal strip, the complete circuits of the telephone are built up. In still other cases the induction coil is mounted on the terminal strip and separate wires or sets of wires are run to the polarized bell and generator, to the desk stand itself, and to the batteries. These various arrangements are subject largely to the desire or personal ideas of the manufacturer or user. All of them work on the same principle so far as the operation of the talking and signaling circuits is concerned. IMG:384091999325875926_fig145_t.gif.png:Illustration_ Fig. 145. Magneto Desk Set Fig. 145. Magneto Desk Set View full size illustration.