Show in u 0 u alinur 0 cadlo merchandising dising 7 W W A 10 s c nami W 0 ww ftc VZ ca i 7 4 i i e sa s RUM i dh arim 41 f 1 1 7 1 l waw rj hj i rj 7 hookup hookup of the tha crystal amplifier the batteries are arc connected to the tha binding posts posta on the right A M MI i J i n i j i jr aa j i nu ur is AI 0 I 1 W oat S sectional view showing the arrangement of the parts parti by MAURICE B ONEIL the amplifier here described to bo be used with a crystal elector detector hai worked more successfully than more than a dozen types recently designed and tested after numerous unsuccessful attempts to perfect ft a more indro dellento microphone type of using sharp edges in contact with pencil lends leads etc they were all dia discarded carded for tilts this one when once adjusted this instrument wilt will not jar out easily I 1 to do not mom mean that it can be thrown about in less lesa manner which will of course disturb the roost most sensitive position of the carbon grains in the transmitter buttons but it Is not as annoying as the more delicate microphone types ot of tal amplifiers forthe for the construction of a three step following parts are needed which are arc easily found in any aan amateur or experimental station 1 three telephone receivers three bpark colls coils six binding posts three pieces of brass I 1 inch wide 9 inches long and A inch thick six pieces of thin sheet iron bent as shown shawnin in fig 3 14 inch wide six pieces of no 12 galvanized iron wire for holding colls coils to base bent as shown in fig 4 three telephone transmitter buttons two mah mandolin dolln E strings one piece VA inch wood 8 indies inches long by 3 inches wide not shown in drawing Is used in back of telephone receivers wood base 8 inches by 10 indies inches inch thick wood base 8 inches deep and 8 inches by 10 indies inches inside measurement the three ford spark colls coils tire are talen out of tile the coll coil boxes care being taken not to break ony any of the secondary wires the compound in the he coll colf boxes boim need not be melted nor tile the secondary sections taken apart after the box has been broken away the primary and core fits are pulled out and prIll primary iary ware wre removed the core Is then wound with six layers of no 24 D 0 0 magnet wire ire the six layers aalop allow a snug fit of tho the primary into the secondary after vio the extra two or three layers of waxed paper la in the tube have been removed the three colla coils are made dike alike the telephone transmitter buttons are drilled and topped tapped in the shank to allow for adjustment of the tension v A 1 1 M 1 ija J fadow 1 T aw fy dimensions dimension for the base bae and brackets bracket on the steel wire to the telephone receiver diaphragm lee eee fig 5 the brass brackets are mounted on the wood base oner after having been bent and drilled as shown in fig 2 the binding post at the end of tile the imse base passes through the hole in the brass brans brocket bracket serving os as a connection to it and at the paine baine time to secure it to the buse A small wood screw Is used 13 ai the second hole in the foot of the tha brass bras bracket to prevent side motion of the latter A hole large enough for or tile the shank of the transmitter button to pass trough through Is drifted in the top of the bracket at fl a t where it will be in elno 5 with the die venter center of 0 tile the telephone when aln n it in hi in a place these will vary with u ith the IV T ferent types of 7 t I 1 tile the small 9 studdard it aldard andard shown shown in fig 3 la Is held heid to the th e base bythe bythe same screw that holds tho the no 12 iron wire to the bottom of the base for tho purpose of supporting tho the colls coils they should bo be clamped with an iron bolt tho the purpose of this po piece of sheet metal Is to give on an increased magnetic pull on the steel wire between transmitter button and receiver helping to give a stronger pull on tho the button butto n and allowing more current to pass through the primary of the spark colls coils which increase the signal strength from step to step the telephone receiver diaphragms are marked at their center and a small hole punched through with a phonograph needle the mandolin 13 string Is passed through gh and a very small hook made at tho the end of tho the wire which la Is then soldered with as small an amount of solder as possible at the outer edge of the diaphragm a small wire Is soldered and connected to the primary of tw the spark sari calls tia ai shown in wiring diagram Ilai nim tile the receivers are placed behind tile tho wooden block and wedged there between vo olvil fi 4 haq tween tile block and wood end piece shown in fig 5 the other details may be easily understood der stood from tile lie drawings furnished furni sheI and should present no difficulties to td the average electrical electric ul experimenter greater amplification may be obtained by the use of higher voltage through the amplifier but I 1 have obtained best results with a small resistance tosi si stance in series with the negative binding post which will prevent the passage of too great a current resulting in tile the heating of the transmitter buttons the first step Is adjusted until best signal strength Is obtained then the second and third the batteries may be dry cells five cells give good results the amount of voltage for each step Is found by experiment and adjustable clips are used from tho the three binding posts at the end of tha instrument news newa |