Part 13 (1/2)

If just to show the principle of it, alth will do, like that of App 3, 4 or 5 A dry battery will do, but if you use the sounder much, an open-circuit battery will soon use itself up

Where much work is needed of the battery use App 9

[Illustration: Fig 95]

The Key like App 119 is best Push-buttons are handy where used only for experies

APPARATUS 121

_199 Telegraph Sounder_ Fig 95 This makes a simple and efficient sounder for short lines The base, B, is 7 4-1/2 7/8 in The back, A, is 7 4-1/2 1/2 in; it is nailed to B The piece D is 4 3/4 3/4 in; it is nailed to A C is a wooden piece 1-1/2 3/4 3/4 in; it is nailed to A, and in its top is a screw, E, which is used as a regulating-screw to keep the ar the poles

200 The Armature, L, is explained as App 77 The two thicknesses of tin at F must not be too thick, or it will take too much battery power to work the sounder If you find that it is too stiff to bend dohen the current is on, try the arrangeulate The whole point depends upon the tin you have The end of L ainst E A hole is punched in the part F, and a screw, G, holds it to D L should rest about 1/8 in above the poles and gently press against a screw or nail, V

201 The Magnets are like App 89 They are made as in App 88, and held down like App 90 These should be placed very near the back, A, so that the armature will be over theainst A Y and Z are binding-posts like App 46

202 Connections Join the coils as explained in -- 125 and see -- 115

Instead of a third or66, hold the two inside ends between a screw-head and a copper bur Thethe wires for a line with two outfits, is shown in App 124 If you have but one key, sounder, and battery, siravity cell is best (See App 9)

203 Hints About Adjusting If you have the right spring to the part F, of the armature, you will have no trouble It must not be so weak that it allows L to strike upon the poles, as the residual netism (Text-book) will hold L down after the current has ceased to pass No springs are necessary, if your tin is right Do not have L too far away froulated by the position of V If you have trouble in getting it to work see App 122 The poles must be opposite in nature

APPARATUS 122

[Illustration: Fig 96]

_204 Telegraph Sounder_ Fig 96 The nets, connections, etc, are like those of App 121, no binding-posts, etc, being here shown The ar upon D A hole is h this is a screw or nail, S The hole h easily This acts as a bearing or pivot L is kept up against V by the rubber-band, J, one end of which passes around the end of L; to the other end of J is a thread, which is tied around a screw-eye, K By turning the screw-eye, the band may be made to pull ulated according to your battery The general diiven in App 121 D isL about 1/8 or 3/16 in above the poles

APPARATUS 123

[Illustration: Fig 97]

_205 Telegraph Sounder_ Figs 97 and 98 This apparatus looks a little ular sounder than App 121 and 122, but it is much harder to make and adjust In this the lower nuts of the bolts are not sunk into the base, and the e this and fasten thee the diiven are for this particular instru 98 is a plan or top-view of it, with di 98]

206 The Base, B, is 6 4 7/8 in The net, M, is explained in App

89 Its wires are attached to the binding-posts like App 46 The armature, A, is 2-1/2 3/4 1/8 in, and made as described in App 71

The piece, D, is 2-1/2 1-3/8 1/2 in, and is screwed to B frohts, C, are nailed to it The uprights, C, are 2-3/4 7/8 1/2 in They are nailed to D The nail, N, runs through both uprights, and acts as the bearing for F to rock up and down upon

The hole for N is 2 in above B It must not be too loose in the holes, or F will rock sidewise, and allow A to touch one of the ht, E, is 2-3/4 3/4 3/4 in, and is screwed or nailed to B from below A screw, G, is put into the side of E near the top This screw has the underside of the head filed flat, and against this the screw, L, taps when the armature is attracted The arm, F, which carries the armature, A, is 4-1/2 1/2 1/2 in, and is pivoted by hts C Fup and down freely The hole for N, in this model, is 1-3/4 in from the armature end

207 The armature is fastened to F by a screw, S A copper bur is put under the head of S to aid in keeping A froh F, and about half way between C and L, is put a screw, I, the lower end of which taps against the head of a screw, H, which is put into D By unscrewing H a little, F will be raised, and A will be brought nearer the poles of M The rubber-band, J, is placed over the head of I, and has tied to it a thread, O, which in turn is tied to a screw-eye, K K screws into the end of B, and by turning it one way or the other, the tension, or pull, on Jin J to pull A up after the current ceases; it net cannot draw A down hard enough to net, M, is explained in App 89, and the construction of one bolt iven in detail in App 88 In this particular sounder the bolts are 2 in long under the heads, thus bringing the tops of the bolt-heads about 2-1/4 in above B M is held to the base by a band of tin, T The yoke ested in App 90 This is the better plan

208 Adjusth you iven, that you will have to try, and change, and adjust before everything ork perfectly A must not be allowed to touch the poles of M when it is pulled down, on account of the residual netism, which would keep it pulled down Adjust this with F The armature must not be pulled too far up from the poles of M by the tension in J; adjust this with I and H If your battery is weak, the pull of J h to raise A

The Battery It is supposed, if you make an instrument like this, that you expect to use it for a line In that case ravity battery like the cell of App 9 See Fig 99 for line connections, and Fig 98 for plan view of this sounder