Show IN Z L cited by U kougl 1 I WP W i hada W gitany amateurs after having built a workable loud talker spoil the whole it thing hi ng by using it in connection with a poorly designed horn bom and diaphragm because they have no facilities for obtaining or making them properly if they would only stop tor for a moment and think of the time and money spent toy by phonograph companies la in designing weir th clr horns homs and reproducers there might be nore more of them who nho would make uso use of these parts tor for this work the loud talker described utilizes the sound box and the horn hom of a hill and idale dale type phonograph the field colls coils with cores of this loud talker are two electromagnets electro magnets removed from an old telegraph sound er r and mounted upon a base as shown TAT OF wo M ICA rao gwim I 1 A n POX pa h 0 alac VIEW AM I 1 ua ma the no upper end of each core Is drilled and tapped to a depth of about one half balf of an inch and a short strip of sott soft iron Is bolted to each each strip should be about 3 16 of an inch thick and as wide as the pole pieces lecea of the magnets they should be of such length that their ends will be 8 16 of an inch apart as shown la in the accompanying diagram detector cups from cartridge fuse ends the amateur who undertakes to make ibis own mineral detectors Is soon confronted by the problem of obtaining detector cups the brass ends of cartridge fuses are useful the small of thirty ampere size does very well for crystals mounted in soft metal cut about three sixteenths inch irom from the opening end this leaves a cup about one quarter inch deep solder to the bottom of this as shown in sketch ketch a ablat flat headed brass screw long enough to make connection under the use tase of the detector countersinking slightly the hole in ohp hasp base will permit the cup to come down properly to mount the cup horizontally on a base or upon a panel cut a serl strip ap of brass about one sixteenth inch thick three e quarters inch long and three eighths inch wide round off each end to improve the appearance drill a one eighth inch hole at one end bend the strip in the center of the right angle and solder to the back of ma mp DEJ U PUT SOL 9 K mor VU ERED 70 the cup in the place of the screw hs h in the previous case this cup can be mounted on the base of a panel by b y a screw through the brass strip to make a cup with screws to mount rabe mineral it la Is best to use a larger luse fuse end the next size does very well I 1 this Thi scup cup may be cut down downto to give the required depth about three tights inch around the wall vail of the scup cup drill three one eighth inch holes reach at right angles to the axis of the tup cup and at degrees to each other these may maybe be tapped and screws inserted to hold the crys crystal or brass nuts may be soldered over each hole hola for the screws such a cup may be a arranged i tor for mounting as previously described it the experimenter Is properly equipped and so desires he be ahn can nickel plate these cups thus greatly improving the appearance A afeie few old fuses tor for tills purpose can usually be obtained from any user of lot electric power 0 radio news ito ato locate and drill switch point holes the following method of locating and drilling holes in a panel for switch contact points true in radius and of equal distances apart Is a real labor adver for the experimenter who builds his own take a piece of sheet brass about ab out 1 82 inch in thickness and of a leng length th according to the ilia radius radios to be used a and nd ali inch wide scratch a line through the center center al A prick mirk point D B set ono one point of divides at 11 and scribe are arc C of the radius to be used prick frick nark mark the point D and dl which are centers of contact points on each side of the electromagnets electro magnets drill a hole in the base through which long machine screws are inserted A nut should be run down dowa on each one to clamp tt it to the base next obtain it a strip of thin first quality mica about three ahree fourths of an inch wide and slightly longer than the distance between the two machine screws drill holes in each end of this strip so that it may be placed upon the two screws in the center of the strip directly over the center of the space between the two pole pieces drill another hole A circular diaphragm placed in the same way could also be used we will koiv now proceed to the winding of the movable core make a form or template ot of two wooden blocks as shown la in fig 2 with a core one fourth of an inch apart they should also be arranged so as to be readily demov able after the coll coil Is wound on this template just constructed wind about DOO feet of no 44 enameled wire after tile the required number of feet ire are wound on the coll coil one side of the form should be carefully removed and thin shellac applied to the exposed side of tho the coll coil after tills this dries remove the core and the other side of the form and carefully shellac the other side of the coll coil after the shellac dries wind very carefully several turns of one fine sewing silk around the coll coil taking care to preserve its shape and thickness now obtain a split copper rivet and insert it in the center hole in the mien mica strip fasten this firmly in place with bellac shellac place the molln moving coll coil between the two legs of tho the rivet and squeeze them lightly together taking care wl nu i to damage the col coil in so doing now assemble the component parts as shown in fig 1 I and over the en tire apparatus place a box anthe top of which Is a large hole to admit the needle on the phonograph reproducer the instrument Is connected without the use of it a step down transformer and Is placed upon the top of the phonograph as shown in fig L 1 the result will be it if properly constructed a loud talker whose oper operation atlon will be equal to the best on the he market 0 radco news and drill holes through the plate at these points G B D and dl D l 1 using same size drill as for contact points to use um drill hole through panel where switch snitch Is to be located put switch or a contact point through hole B and la in hole just drilled in panel it if an even number ot of holes hoes are to be 0 C drilled set plate as in cut placing drill in hole dl D l 1 drill panel move moro plate to lefts left putting in a slightly tapering plug through the hole D and la in hole bole in panel just drilled and drill again at dl D l 1 repe at tills this method until all holes are drilled perfect in radius and spaced equal distances apart and an easier way to do the job if an odd number ot of contact points are to be used drill first hole on center line jacks as brackets for V T socket mounting jacks when used in an ordinary amplifier can also be used as brackets upon which the shelf holding the V T Is mounted the frames are inverted and drilled as shown in the sketch corresponding holes are drilled in the shelf the jack can either be tapped or a bolt passed through tola this adds to tife the compactness of the set and simplifies the wiring the sketch I 1 using the jacks as a brackets bracket to support a panel Is self explanatory but only shows one jack this process 13 repeated on the other two forming a firm mounting to tor r the shelf pretty speedy mat reading the radio waves warn are sent out at vibrations as high as one million a second which would car ry them around the earth six umes times la in a second pat Beg be orryl it wont belongie be long before be thim before they start the comparable superlative lato late advises advices are that china Is in to have hale a largest radio r a dlo truon n in the world A |