Show edited by 0 douglas editor of 1110 merchandising by HARRY L L GRAY the honeycomb or lateral wound colls colla have been found to be very effa dent clent on all wavelengths wave lengths and tho the station which Is equipped with those colls coils will be ablo able to receive from all stations no matter what tho the wavelength may be tho the shortest or the longest waves may be received on the name hame set the tuning to all done by variable condensers or vario varlo meters according to the circuit used winding the coll the amateur can easily wind chesi colls coils for himself by following the directions ions here given also the manner of mounting hero here described Is I 1 think much simpler and neater than that which Is generally used procure some good cardboard tubing which Is two inches inside alame ra im LL simple type of coupler for homemade honeycomb colls ter As aa the colls coils are to bo be one inch wide the tubing should be cut in sections of that width havo a block turned to fit this tubing nicely if it is 13 not possible to have it turned it may bo be whittled place one of your tubes on this and mark two lines at the edge of the tubing these lines ore fire then marked oft off evenly with a compass into 23 25 spaces then small brads bradi should be lightly driven on theae lines on the spaces Bp ace before the tube Is placed on the block however the contact strips should bo be placed on the tube these are merely strips of thin brass or copper about one fourth inch wide it should bo be clinched on tightly as shown in fit the drawing when you are ready to wind solder the end of your wire to one of these contacts so that it will bo be covered with the winding also solder another short piece to the other contact and when through winding cd C d fk rm L I 1 the colla coils can be wound by hand around a piece of wood into which are arc driven brads solder the end of the wire to this short piece the soldered joints will then be concealed wind according to the drawing start at a peg nearest the contact and wind to the thirteenth peg on the opposite side which Is just halt half way around and then back to the next nest peg ahead of the one you started from when you have continued in this manner until all the pegs have a wire on them you vou will have 25 turns or one layer on the coll coil material and wave lengths use no 24 cotton or silk covered cohered wire for wavelengths wave lengths up to 1000 U meters c and on the larger colls coils a finer w wire 1 re can caa be used to save space in this case as fine as no 30 can be used I 1 have never seen enameled wire used on these colls coils the following number of turns have been found satisfactory on wavelengths as given 25 turns up to meters 30 turns to COO meters 44 CO TIM laoo lo oo 0 J when co bollt ila are wound fiber strip it Is pla placed ad around to give rigidity rigidly and to protect winding BO 50 turns OW COO to SW meters 73 turns to 1000 meters IW turns OW to 1100 meters turns to 2500 meters ni eiers other wavelengths wave lengths can bo be from froin tarsi ilgunas il guns thi wavelength wave length will depend considerably sider ably upon the size of aerial used alan the capacity of the condensers den sers the variable condenser conden seron on the primary should be of V and should be arranged with it 11 switch so id it cue car tie lie connected conn cacil either in series or la in littral lel the secondary variable condenser should he be of 00 N U F I 1 after the colls ure tire wound it cover will improve tho appearance chis la is tunde from jiin tiber liber sword hoi irl ut card cardboard buard fan an be usei usein A luw of nf diamond shaped holes should be cut along alone the center of the strip the th strip 14 9 then glued on oa and am wrapped with twine until the glue has haa set tho the winding will project slightly over the edgo edge of tho the tubing so the cover strip should bo be made slightly wider thun than the tube after the cover to la glued on and set remove the twins and smooth the lie joint in the cover with will sandpaper the coll coil should then bo be dipped in white shellac of the best grade or better still celluloid varnish which can bo be made from the following formula amyl acetate I 1 pint rusel fusel oil tre fined i pint V anz n 0 1 pint wood alcohol r i pint castor oil by weight I 1 ounce soluble cotton 2 ounces add chemicals in order given soluble cotton being last allow to stand 12 hours and strain through cheesecloth after the coli col has been dipped and Is dry the varnish should be scraped from tho the contacts and they should always be kept clean and bright it Is a good idea to mark each coll coil with t the it e number of turns before varnishing the tha coll mounting the mounting for these colls coils sometimes called the mechanical coupler Is quite simple as will be seen from the drawing one coll coil Is mounted sta flonary while the other Is movable lo 10 for r tho the coupling the round blocks s should hould be turned same size as the block used in winding the contacts are thin spring brass A slot Is cut in the side of the block and the contact fastened with a small screw and bent bad back over oer the screw after the lead wire has been soldered it should be quite springy and project slightly from the block which will insure good contact when tho the coll coil Is slipped in place dy by making the contacts an inch or more long they will always be in contact with the coll coil even afat if it be turned one way or the other in placing it on the block the dimensions of the arms armi need not be exactly as given but should be long enough to allow the larger colls coils to be used an ordinary brass hinge Is used on the movable arm brass screws should be used in nil all places as iron screws would havo have some effect on the working of tho the colls coils instead of using a n base the arms can be mounted directly on top of a cabinet and the knob allowed to project over the panel which makes a convenient position tor for operating it if it Is desired to use three colls coils instead of two it Is only necessary to add another movable arm the stationary coll coil should be left in the center flexible leads must be used on the movable colls coils and these should be soldered to the contacts the knob for adjusting the coupling Is not absolute absolutely ly necessary except in certin hookups hook bips ups where the hands of the operator have a capacity effect 0 D science ud invention iland nd radio H simple loud speaker has proven efficient the device here described has proven its efficiency in many rigid tests it la Is neat simple effle efficient tent and it may be made at practically no cost the materials are as follows ono block of soft wood 2 by 2 by 1 inches to common tacks one rubber band the method of construction Is seen clearly ly by the drawing the hole I 1 in n the block Is drilled slightly larger than 4 1 A TWO the horn end it if it tapers it the horo horn end Is not of conical shape chape such as a phonograph tone ton earm arm the hole Is made just large enough to fit snugly the receiver Is placed as la Is shown in the cut and it works t try to beat that for simplicity 0 0 science mid and invention anil and radio nw news extra binding post instead of switch why y use a series parallel switch when one additional binding post on the he front of the panel will be dent ordinarily linar fly for parallel conned connect tarns the ground wire would be continued front from 0 to B outside of the T A 0 4 S 0 7 0 0 e 0 0 C J L i bunel it if a series connection Is 3 do adred tills this connection is broken and the tha iderial fastened to U B instead of A this kves tho the mst cost of aa n series parallel paral lri ni tili mid WO tha wiring wiling |