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Show Detector Cups From Cartridge Fuse Ends The amateur who undertakes to make his own mineral detectors is soon confronted by the problem of obtaining ob-taining detector cups. The brass ends of cartridge fuses are useful. The small of thirty ampere size does very well for crystals mounted la soft metal. Cut about three-sixteenths Inch from the opening end This leaves a cup about one-quarter inch deep. Solder to the bottom of this, as shown in sketch, a flat-headed brass screw long enough to make connection under the base of the detector. Countersinking slightly the hole in the base will permit per-mit the cup to come down properly. To mount the cup horizontally on a base or upon a panel cut a strip of brass about one-sixteenth inch thick, three-quarters inch long and three-eighths three-eighths Inch wide. Round off each end to Improve the appearance. Drill a one-eighth Inch hole at one end. Bend the strip in the center of the right angle and solder to the back of SCREW SOL- " V- DERED1QCUP f NUTSOL: 1 mm 1 the cup In the place of the screw as In the previous case. This cup can be mounted on the base of a panel by a screw through the brass strip. To make a cup with screws to mount the mineral it is best to use a larger fuse end. The next size does very well. This cup may be cut down to give the required depth, about three-eights three-eights inch. Around the wall of the cup drill three one-eighth inch holes, each at right angles to the axis of the cup and at 120 degrees to each other. These may be tapped and screws Inserted In-serted to hold the crystal, or brass nuts may be soldered over each hole for the screws. Such a eup may be arranged for mounting as previously described. If the experimenter is properly equipped and so desires he can nickel plate these cups, thus greatly Improving Improv-ing the appearance. A few old fuses for this purpose can usually be obtained from any user of electric power. ( Radio News.) and drill holes through the plate at these points, B, D and D-l, using same size drill as for contact points. To use, drill hole through panel where switch is to be located, put switch or a contact point through hole B and In hole just drilled In panel. If an even number of holes are to be drilled set plate as In cut, placing drill In hole D-l ; drill panel, move plate to left, putting in a slightly tapering plug through the hole D and in hole In panel just drilled, and drill again at D-L Repeat this method until all holes are drilled perfect in radius and spaced equal distances apart, and an easier way to do the job. If an odd number of contact points are to be used, drill first hole on center cen-ter line. |