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Page:Popular Science Monthly Volume 90.djvu/810

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794

��Popular Science Monthly

��Making a Simple Relay Key for Wireless Operators

THE arrangement in the diagram shows a simple and inexpensive method of constructing an efficient magnetic relay key to be used with an ordinary Morse key or automatic sender. An ordinary heavy key of the type used in wireless work is shown at

���An ordinary heavy key of the type used in wireless work with magnets

��A. It is connected in the primary circuit of the transmitting transformer by the terminals B in the usual manner.

A pair of magnets obtained from an ordinary 4-ohm sounder is represented by M and fixed in the position shown in any convenient manner. A sounder armature D is fastened to the base of the heavy key lever just beneath the knob, by means of a screw and washer. The magnet coils M are connected in series through their terminals E with several dry or storage- cells and an ordinary Morse key.

It will be readily seen that with this arrangement, manual operation of the light key will cause simultaneous operation of the heavy relay key automatically. By sub- stituting a vibroplex sender in place of the small key, perfectly satisfactory results may be obtained. Care must be taken to adjust correctly the spring tension on the key lever of the heavy key to secure the best results. — Norman A. Woodcock.

��A Multiple Key for Sending Wireless Messages

BY mounting two key levers side by side on a common base a high speed hand- operated trans- mitter in its sim- plest form is ob- tained. The keys should be con- nected in parallel. Adjust the spring on one so as to raise the lever sharply for the dots, and the spring on the

���Two telegraph keys mounted for fast sending

��Other so as to work more slowly, for the dashes. Two easily built strap keys are suitable for the purpose.

��Care is necessary in order to send good, fast, clean-cut Morse in this way, but with a little practice it can be done, and operat- ing speed will gradually increase. Both keys are of course manipulated with one hand. — John B. Rakoski.

��A Novel Crystal Support Made of Flashlight Globe

IN the illustration, A represents the base of a miniature flashlight bulb, all parts except the shell having been discarded. When this is half filled with solder the crystal is molded in. A set of minerals may thus be mounted to work in conjunc- tion with a miniature porcelain base socket, B, which is fastened to the de- tector base. The mineral itself may be screwed into place and rotary adjust-

���The lamp screw and the porcelain base

��ment of the mineral secured in the same manner. Contact is made from both binding posts of the base socket. — Joseph Braff.

��A Multiple Electrode Rotary Spark-Gap

IT is a well known fact that there is a great deal of energy lost in heat at the electrodes of the spark-gap. This is par-

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��Multiplying the electrodes will increase the efficiency of transmitting apparatus

ticularly noticeable and very objectionable in a plain open gap. The rotary-gap over- comes the difficulty to a certain extent, on account of the cooling action of the wheel; but most amateur rotary-gaps can be im- proved upon in this respect.

An increase in radiation will be noticed in most cases if a number of electrodes are used in place of single stationary electrodes. The arrangement shown in the drawing is simple and will amply repay the careful builder. — W. A. Parks.

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