We use Optical Character Recognition (OCR) during our scanning and processing workflow to make the content of each page searchable. You can view the automatically generated text below as well as copy and paste individual pieces of text to quote in your own work.
Text recognition is never 100% accurate. Many parts of the scanned page may not be reflected in the OCR text output, including: images, page layout, certain fonts or handwriting.
Dry Cell Batteries — Schuete 457
Temperature
High temperatures result in a drying out of the chemicals in a battery and therefore decreases its shelf life. The energy obtainable from a battery is greater if the battery is kept warm because its resistance decreases. Experience shows, however, that batteries should not be stored or used at temperatures much above usual room temperature. If the projection booth is normally very warm, the shelf life of the batteries in it will be shortened.
The cold increases the resistance of batteries and lowers the flash. Dry cell batteries have been used in Arctic and Antarctic conditions where they were insulated by heat insulators and found to work satisfactorily. Unless the current drain from them is high, the normal cold temperatures that would be experienced in sound projection should have no influence on them. If dry cell batteries are used in motor trucks, and should stand at freezing temperatures for several days at a stretch, it is expected that they would not operate as efficiently as if the trucks were housed in a warm garage during rest periods.
Insulation
Because of the high voltages that are sometimes used, dry cell batteries should be mounted in insulated cabinets. This will prevent set currents from flowing through the containers of the batteries and producing voltage fluctuations and perhaps noise. Batteries should be spaced with air insulation between them whenever possible, and if not in an insulated cabinet, they should be mounted on strips of paraffined cardboard or wood to allow some circulation of air around them. Moisture or steam should be avoided. Where they are used out of doors and subject to temperature changes, the connections should be made so that if there is any precipitation of moisture on the surface of the batteries, it will not cause a circuit between terminals.
High Voltage Batteries Eight or ten years ago attempts were made to use high voltage batteries on the ''B" circuit of broadcast receivers. They were not successful, with the result that radio engineers standardized on a 45 volt unit which contained thirty dry cells. Receivers and vacuum tubes were designed to use tliese batteries or multiples thereof, such as 90 or 135 volts.