Show I 1 TT il J W VI vifa fV tl THE 4 HOME RAZE 1010 how to make and use it cw by A hyatt VERRILL inductances AND TUNING COILS to receive and hear sounds sent from transmitting stations by radiophones radio phones clearly and without interference or confusion a device of some sort Is required which will cut out all waves save those desired this Is known as tuning and the instruments or appliances used to accomplish it are called tuners there are now a great many different devices for tuning such as tuning colls loose couplers varto vario couplers vario varlo meters variable condensers etc of these all but the variable condensers which see are colls coils of various types the simplest but by no means the most being the simple tuning coils cells these consist of a coil of bare wire wound about a core or cylinder of wood fibre fabre or p pasteboard aste board and provided with sliding contacts as hown in fig 30 in which A pi li the coll coil G B the me eliae slide rod and C the slider dy by moving the slider from coil to coll coil of the wire the wave length of the receiving instruments may be adjusted to catch the desired sounds of that wave length such colls coils are very easily made by winding a pasteboard tube which should be soaked lu in melted time to render it waterproof with baro bare copper wire about no 18 making about 40 turns and leaving a space of about 1 10 inch between the turris turns it if two or m more ore sliders or contacts are arranged still finer adjustment will be attainable while by providing rotary switches wit wah II 11 five contacts as shown la in fig 31 still better results will be secured although is as stated staled these theise colls coils are casil easily y made yet they ari are so cheap that many prefer to purchase them ready mado made rather thun than bother making them simple culls colla or inductances however are even bim simpler as at they consist merely of a lew few turns of insulated copper wire aou bound nd on a pasteboard tube the number b vr of turns depending upon the wave lengths to bo be received in some sets seta there Is but one coll coil or heli fig 32 while la in other sots sets there are two a primary y and secondary fig 83 end and as a the he coll coil should be tapped and tho the circuit connected at t the be fig fie 84 81 this Is best done by taking a loop or twist in the wire at the desired point and the thea continuing winding as pis fig sa 35 of course in making the connection at this tap off the wire tire should be scraped free of insulation to make mahe the joint after which it should be wrapped with adhesive tape in malting making those these simple inductance colls coils it Is best to put on more turns of wire than you think 11 actually required as it Is far easier to remove one turn at a time until the desired wave length Is than it la Is to add turns after the instruments Instrument a ure are set up similar simple colla coils are used in many parts of receiving sets such as the radio choke in fig 59 69 L etc by making several tali olta and then I 1 leading them to the various contacts of a multiple point switch fig SO W 0 C excellent results may be obtained especially with the smaller crystal sets with a single simple coil another way by which waves of varying lengths way may lie be received by means ot of simple colls coils without tuning devices la Is to I 1 have bave several beveral colls coils ot of various sizes so arranged that they runy may bo be connected connect cl or disconnected with your set at mill this may bo be done either by mehul of plugs and sockets as an la in fig 38 36 A or by switches with severa several I 1 contacts as shown in fig SO 30 B still oner finer adjustment may be oata obtained led by providing each coll with a slider allder or i i similar tuning device this will give a wide range ot of wave lengths and will obviate all need of taking turns oil off the colla cells and as such colla coils aro are very easy to mako make you can havo as many t us IS you I 1 desire of different sizes another very different type of lu iu 1 duchance coll consists of two windings known as pair primary nary and secondary and are similar to the ordinary spi sparking irking colls coils used in older type automobiles |