SEVENTY-FIVE YEARS OF THE TELEPHONE 



231 



^5 



UJ z 



Q (n> 



(/).Q 



- tro 



cr 11^ 



CD 



Qt- 



^^ 



-20 



-25 



-30 



-35 



1000 

 FREQUENCY IN 



1500 2000 2500 3000 



CYCLES PER SECOND 



4000 5000 



Fig. 4 — (a) Artificial mouth response of the station set transmitter; (b) available power 

 response of station set receiver. 



larger hand-held receiver. This was the result of improved magnetic circuit 

 and materials. 



The handset of 1937^°- " included a new design of transmitter which was 

 made available about 1934 for use in the earlier handset. In this transmitter 

 the freedom from resonance was preserved and the effect of the improving 



