Comparative sensitiveness of some common detectors of electric oscillations (1910) (14571382189)

Identifier: comp65275421910140140unse (find matches)

Title: Comparative sensitiveness of some common detectors of electric oscillations

Year: 1910 (1910s)

Authors:

Subjects: radiotelegraphy measurements and use of instruments Telephony B6210F Telegraphy

Publisher: National Bureau of Standards

Contributing Library: NIST Research Library

Digitizing Sponsor: NIST Research Library

Text Appearing Before Image:

Fig. 5 In Table VIII is given the relation between oscillatory energyin the main circuit and the audibility of signals in the telephoneof the vacuum detector, as determined by the shunted telephonemethod. The audibility is seen to be proportional to the energy.The telephones furnished with the vacuum detector had a resistanceof 8300 ohms and were connected by means of a step-up transformerto the detector circuit. 8 This shows the disadvantage of constructing receiving apparatus with fixedcoupling. 488480—10 8 54-0 Bulletin of the Bureau of Standards. (Vol. 6, no.4- TABLE VIIIReceived Energy and Audibility of Signals in Fleming Vacuum Detector Perikon Vacuum detector D A 43 38 21 20 10 9 5 5 THE AUDION. (Fig. 6) The De Forest form of vacuum detector, called by him theaudion, is shown diagrammatically in Fig. 6. Here V is anexhausted glass bulb containing a tantalum filament F, heatedby three storage cells S, a metal plate P and a metal grid G be- T

Text Appearing After Image:

Fig. 6 tween the filament and the plate. The filament and plate areconnected externally through a battery B of 36 small cells, anynumber of which can be thrown into the circuit, and a pair ofhead telephones of about 1200 ohms resistance. The filament Austin.) Detectors of Electrical Oscillations. 541 and grid are connected through a small fixed condenser C and aninductance L, which is coupled to the oscillatory circuit. The action of the detector appears to be as follows: The heatedfilament F is charged negatively by the battery B and a steadystream of negative electrons flows from the hot filament to thecold plate producing a direct current through the telephone.When an oscillatory electromotive force is impressed on thecircuit F L4 G, the negative current can flow from F to G insidethe bulb and not in the reverse direction, just as in the Flemingdetector. The grid G thus becomes negatively charged and asit lies between F and P the direct current through the telephoneis decreased as

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