A SOUND PROJECTOR SYSTEM 



203 



record up substantially to the same energy value as that obtained from 

 the magnet coils of the disc reproducer. The filaments are heated 

 from a 12-volt storage battery. Small dry batteries supply its plate 



THEATRE HORN 

 CONTROLS 



THEATRE HORN KEYS 



OUTPUT CONTROL 

 PANEL 



PLATE CURRENT METER - 

 GAIN CONTROL SWITCH-; 



41 -A AMPLIFIER* 



WESTERN ELECTRIC 

 205 TYPE VACUUM -~ 

 TUBES (AMPLIFIER) 



42 -A AMPLIFIER-*- 



PLATE CURRENT METER-^ 



WESTERN ELECTRI 

 211 TYPE VACUUM 

 TUBES CAMPLIFIER) 



43-A AMPLIFIER 



MONITOR HORN 

 CONTROL 



monitor, horn key 

 -input key 



^filament current 

 "meter 



-filament control 



_plate current 

 push buttons 



-filament key 



western electric 

 ~~239 type vacuum 

 tubescunder cover 



western electric 

 205 type vacuum 

 tubes (rectifier ) 



starting switch 



plate current 



METER 



WESTERN ELECTRIC 

 211 TYPE VACUUM 

 TUBES (RECTIFIER) 



STARTING SWITCH 



Fig. 9 — Amplifier Panel. 



current and also the polarizing potential for the photo cell. These 

 batteries and the battery leads are shielded. 



Vibration of a vacuum tube often produces sufficient motion of its 

 elements with respect to each other to effect changes in the stream 



