. An elementary manual of radiotelegraphy and radiotelephony for students and operators . s of one windingbeing insulated, wliile those of the otherare connected to a pair of slip-rings, r, ?•,and bi-ushes, by means of which the oscilla-tions can be passed through the winding. On testing this apparatus, with nooscillations acting, there was no potentialdifference at the brushes. On wavesarriving, a steady detiection of the gal-vanometer was obtained in a directioncorresponding to an increase of by the armature acted upon bythe oscillations. By suitably proportion-ing the turns
. An elementary manual of radiotelegraphy and radiotelephony for students and operators . s of one windingbeing insulated, wliile those of the otherare connected to a pair of slip-rings, r, ?•,and bi-ushes, by means of which the oscilla-tions can be passed through the winding. On testing this apparatus, with nooscillations acting, there was no potentialdifference at the brushes. On wavesarriving, a steady detiection of the gal-vanometer was obtained in a directioncorresponding to an increase of by the armature acted upon bythe oscillations. By suitably proportion-ing the turns in the winding the sensibilitywas considerably increased. The usualspeed employed is about five to eight revolutions per second. Higher speeds have been tried, and givea larger eflect, but the zero is not so steady. Telephonic signalscan, of course, be received simultaneously by connecting to thewinding at some point before the , is commutated. AVheua relay alone has to be actuated, however, it may be advantageousto so arrange matters that the generated do not exactly p. [Reproduced from The KUc-trician l>y permiuion u/the ProprUlori. Fig. 10. 2IO RADIOTELEGRAPHY balance, and a small initial current, insufficient to actuate therelay, passes all the time through it. The change can be rapidly-effected by a very slight shift of the brushes. 5. Thermal and Thermoelectric Detectors.—An electric oscil-lation, being a form of electric current, produces heat in a circuitthrough which it flows. The heat produced per second is pro-portional to the resistance of the conductor and to the squareof the effective or value of the cuiTcnt. This mean squarevalue is called the integral value of the current. Accordingly, ifthe oscillations consist of separate trains, these not being veryclose to one another, the integral value of the oscillations maybe small, although the maximum value in each train may bevery considerable. If we call J the integral value of the current
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Keywords: ., bookcentury1900, bookdecade1910, booksubjecttelegra, bookyear1916
