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Show Novel Detector Can Be Built formall Sum A new detector sfano. The control is universal and when once adjusted will stand quite a jar. The principal feature of this detector Is the small sum for which It can be made. The pencil, which is of the ever-sharp type, can be purchased for 10 cents and the rest of the parts are found In nearly every amateur's junk box. The lead from the pencil Is removed and a cat whisker is soldered to the bar that runs through the center. If the type of pencil you purchase has no bar through the center, but just a clutch, use a piece of copper wire ths size of the lead that is used In the pencil and solder the cat whisker to It. Next a one-half-Inch ball-bearing Is soldered about one and three-quarter inches from the blunt end of the pencil pen-cil ; this can be done very neatly by heating the ball with a gas flame and putting a drop of solder on It. A little flux Is put on the pencil' where It Is to unite with the ball, and the pencil is applied to the ball while the solder is still soft.- You will then have a good joint. Next make two little angles of sheet brass, through which drill a hole three-quarters of an inch and two holes one-eighth of an inch. The former hole is to form a socket for the ball, which sets between these two angles of brass when mounted on the base. The crystal cup which is soldered or riveted to another brass angle Is then Sip Lfyitor?7t A Crystal Detector Using an Ever-sharp Ever-sharp Pencil for Adjustment. made with two small holes for mounting mount-ing It to the base. A knob for adjusting adjust-ing the pressure Is made by using a composition finding post. Solder a small screw to the end of the pencil ; an old battery terminal Is very good for the purpose. Screw on the composition compo-sition finding post and assemble and mount, the parts on a base, which can be made of bakellte, rubber or a piece of hard wood. Run one wire from the crystal cup to one binding post and one from one of the sockets to the other binding post, which can be placed to suit the builder, build-er, and you then have a detector that can be adjusted In every way. Dimensions Dimen-sions of all the parts are not given, but are left to the discretion of the builder. |