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Page:Popular Science Monthly Volume 89.djvu/299

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Popular Science Monthly

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��Modified Audion is New Telephone

Till", newest oscillation generator to he used in radio telephony is a modification of the Audion detector, which Dr. Lee de Forest, its inventor, calls the Oscillion. As applied to a low- l)oweretl transniiiting instrument, this device consists of a tubular bulb con-

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��A modification of the audion detector used for wireless telephone transmission

taining a straight filament surrounded by a helical gritl antl cylindrical plate. The illustration shows a small panel Oscillion Telephone. The front dimen- sions are only about 8J4 by 1 1 ins., yet the assembly includes the Oscillion bulb itself, a telephone transmitter, a poten- tio meter for adjusting the higii poten- tial applied lo the plate circuit, a switch for starting and stojijjing the oscilla- tions, a rheostat for the filament current, a switch (at the upper left-haiul corner) controlling the radiated wa\elength by cutting in more or less of the variable loading coil mounted back of the panel, and binding posts for connection with the antenna and ground.

��Reducing Arcing at Key Contacts

USINO a sending key on the iio-volt circuit gave much trouble because of arcing at the contacts. This difficulty was remedied by placing two horseshoe magnets on opposite sides of the con- tacts. It was found that the magnets should be close to the contacts but should not touch them. The magnets were fastened on blocks of wood, with brass strips, as shown in the cut below. By their use, the arcing was decreased considerably. Stronger magnets or powerful electromagnets would be still better. — B. ScHUMM.

��The use of two horseshoe or elec- tromagnets will prevent the oc- currence of arcs at the contacts

A Good Loose- Coupler Switch

THE diagram shows a loose-coupler switch which will positively stay tight. In the illustration, /I I and ^6 are nuts of which A i may be used to elevate the knob. Note that A 4 holds A 3 in check. The nut A 5 may be omitted. The knob B is an ordinary wooden disk used in the game of checkers. The bolt C is of brass or nickel, and D I and D 2 are copper or brass washers. The wash- ers arc stationary but the nuts ino\e with the knob. The strip of thin copjier or brass E has its edges be\eled at the contact buttons. The contact bolt is marked /^ and the contact wires A' i and A' 2. This arrangement is not only cheap but easily constructed. When the \a- rious parts of this switch are connected it will remain tight under all working conditions, necessitating no additional care. — K. C. H.amilton.

���A tight loose-coupler switch

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