| Show pancake inductance coils easy to make experimenter experimenters will be interested in the following description of how to make wake a novel set of pancake inductance colls coils which are easily co construct ed and do good work the coll coils can be arranged on pinga plugs similar to those used on spiderweb spider web roll voll a or connected with flexible lead leads two perfectly flat cut surfaces of wood or heet sheet metal for a form as shown in fig I 1 are bound to together ether ith a bolt baring having two outside asberg for holdi bold rm 1 0 I 1 0 bolm 0 exar construction of coll coil ing tn free fret ends of oil muslin and a apac ina ling washer the thickness of the wire to be used thirty turn turns are wound in pancake helix form of no 22 S 8 a CL wire half inch trips strips of ot oil on muslin are arranged as shown la 14 fig 2 and as wire Is 13 wound sticks to muslin which bad previously been coated with wu heavy al shellac bellac when allowed to dry and removed from form the coll coil Is coated with shellac and again allowed to dry presenting a rigid article two inch colls are used one as a primary la ira the antenna circuit with a variable condenser la in series and the other sem secondary dary la in the th grid circuit the two coils when laid flat upon the table one on on the other can be made to produce any degree of coupling by sliding horizontally later lister a third cou coll of similar construction st but of fewer turns Is connected la in the plate circuit for regen ration with GO 50 feet of lamp ip cord laid on hallway floor as an in antenna in conjunction A I 1 oil mush fal with a detector tub tube and one stage of amplification excellent results are obtained such colls coils can also be used as primary and secondary of radio frequency transformers the ratio of turns may my be b made 2 to I 1 and the proper number of turns wound so aa to corer cover any desired band of way watt length |
