Dry Cell Batteries for Recording and Projecting
W. B. Schulte · Transactions of the Society of Motion Picture Engineers · 1929
From inquiries received from sound-picture engineers and sound studios, we know that dry cell batteries are being used to a certain extent in recording and projecting. The details of why and how these batteries are used are not always available, probably, because the art is still experimental and perhaps also because some of the methods are being held secret. At any rate the interest in dry batteries indicates that they are becoming a standard part of the equipment. This being the case, a few words concerning dry cell batteries and their characteristic might be of interest to the motion picture engineers.