Page:Popular Science Monthly Volume 91.djvu/167

 Popular Science Monthly

��Keyless Lamp Socket for Switching Electric Currents

THE well known key socket for electric lamps requires at least thirty separate and distinct pieces, the assembling of which is an important item in estimating the cost of production.

A new socket has been devised which may be made of less than half the usual number of parts. Instead of having a key the bulb itself serves to switch the current on and off.

Pushing the bulb inward about a quarter of an inch causes a spring finger to snap in- to contact to connect one side of the circuit, while the central contact point of the lamp is caused to engage with the terminal of the other side of the circuit, thus turning on the current without a push button or switch lever.

In order to cut off the light, the lamp is drawn back so as to sever the connections, the act of push- ing in or draw- ingout the bulb being far less injurious to the threaded end of the socket, or to the fixtures, A part tarn of the socket than the turn- awitches the current on or off |ng operation

of the key.

The drawing shows the socket made of two parts, the lower end, which is threaded to receive the lamp, being adapted to slide within the upper portion that is attached to the fixture. An upwardly-projecting spring finger, the lower end of which is attached to the inside of the lower shell, has its V- shaped upper end normally resting within a recess formed through the insulating material, so that when the bulb is pushed upward the V-shaped end is caused to snap over and engage with one terminal, while a spring finger on the opposite side of the insulating block contacts with the central terminal of the bulb.

It will be observed that by this arrange- ment both terminals are out of the circuit when the electricity is cut off. By loosen- ing the two screws which hold the shells together the entire working parts may be withdrawn, together with the insulating block, affording a convenient and readily accessible means for attaching or repairing the wires. — J. S. Zerbe.

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Curious Circuit for Audion On a Wireless Set

IT has often been said that it is not possible to use an audion bulb in con- nection with a simple double slide tuner. But experiment has proved that a hook-up may be tuned very closely

���Diagram showing an audion bulb in con- nection with a simple double slide tuner

��and accurately, the strength of signals from all stations being much greater than when the same audion is used with a receiving transformer. On a single-wire aerial 50 ft. high and 150 ft. long, the time signals from Arlington were received over 500 miles under all weather conditions. As will be recognized by those familiar with vacuum bulb circuits, the arrangement shown is very different from the normal arrange- ments on the usual wireless set.

��Conversion of Kilometers to Nau- tical and Statute Miles

WIRELESS telegraph transmission dis- tances are often stated in kilometers, nautical miles or statute miles. To convert the number of kilometers to nautical miles, multiply by fifty-four and point off two decimal places. To convert from kilometers to statute miles, multiply by sixty-two and point off two places. If the distance is given in statute (or land) miles and you want it expressed in kilometers, multiply the number of miles by 161 and point off two decimal places.

��An Experimental Wireless Aerial Made of Zither Strings

WHILE experimenting with several dif- ferent types of novel aerials I found that by connecting together all the strings of a zither and substituting it for the aerial with an inductive coupler, fixed condenser, silicon detector and a pair of 2000-ohm telephones, I could hear a number of local stations very clearly. — Yk Drobe.

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