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A ItlOSlS'lWNCK I{A1»I(» Ti;i,i;iMi(>\i;. 



K. R. Uamskv. 



In riulid IcIcplKHics we luivc a source nf alli'iiial iiiu' ciiri-cnt nf hii^li I'l'c- 

 (|U('ii<-y wliicli sends eiiireiil eut inlu llie aerial. 'I'lie <list iirhance in Hit! 

 ether whicli is caused i).v lliis cuirenl is called the cariaei' \\a\('. The 

 amplitude of this waxc is chan.i;c(l or \aiie<l hy some means which is con- 

 trolled by the voico. This <levice is Uimwii as the modulator. 



Since the three electrode vacuum tube has come into use. tubes are used 

 as fjenerators of the carrier Wiive and also as modidators. This is usually 

 accomplished by connecting the telephone t lansmiltei- to the tubes with 

 tuned or untuned inductance coils. In the case of the tuned coils, each 

 set of coils nuist be separately tuned for every change of \\a\-e len.u'th. The 

 untuned inductiUice method avoids this dilliculty with a certain loss of 

 ettieiency. In either ca^^e one coil is liable to affi'ct the second coil so that 

 disagreeable cross squeals are set ui> in the set. 



The cascade amplifyinj; receivint; sets have the same defects so that 

 all amplification is produced by audio coils, untuned iron core coils, or by 

 resistance amplitication. Tunin.i,' bein.ir in the main circuits alone. 



With the idea of simplicity and cheaimess. 1 have devised a wireless tele- 



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I-ijr. 1. A Kosistancc Kiulio TclcplKnir. 

 phone connection in which the modulation is acc(tmplished by nu>ans of re- 

 sistances alone. The circuit is diagramed in fijiure 1. Tiie oscillatiu}; cir- 

 cuit consists of the aerial, the in<luctance. L. and the variable oil con- 

 ilenser, C, connected to the ground at G. All tuning is accomplished by 



