Abstract :
PHONOGRAPH reproducers, which convert the mechanical motion of the stylus to a corresponding electric voltage, have been in commercial use for the past two decades. They have employed a wide variety of voltage generators such as carbon microphone buttons, variable reluctance magnetic circuits, moving coils in magnetic fields, and Rochelle salt crystals. Although excellent performance has been obtained with many of these types, there has been a continued effort to reduce the mass of the moving system and to simplify the mechanical construction, even to the extent of sacrificing output voltage.
