Popular Science Monthly 



285 



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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o o o 



A- 



o o 



o 

 o 



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 



