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- 



lt>^ »i>'i 



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. 



