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.
E. R. P. I's NEW PHOTO CELL
ERPI recently announced and installed the new 3-A photo-electric cell. This new cell has a number of improvements over the 1-A and 2-A both physically and electrically.
The greatest difference lies in the use of caesium compound as the photo-active element instead of a preparation of potassium as used in the 1-A and 2-A. The caesium oxide is coated on a half cylindrical electrode and a small vertical rod forms the positive electrode. No. 1-A and 2-A employed as the photo-active element a potassium preparation coated on the inside of the bulb with a ring-shaped member forming the positive electrode.
The advantage gained by this new cell is the reduction of system noise which accompanies its use. The response from the cell being greater, the amplifiers can be operated at a reduced gain, thus reducing the volume of any noise producing element within the system. This makes the new cell an important factor in enabling sound reproducing equipments to do full justice to recordings made by the new noiseless process. Beside output efficiency such as the ability to produce a more faithful electrical copy or translation of the sound track its ability to maintain its electrical and circuit characteristics unchanged and its immunity from rapid deterioration and loss of its sensitiveness in storage or use.
The sensitiveness of a photo-electric cell is the current it will pass for a given amount of illumination, usually varies with the color of the illumination. The cell is more sensitive to some parts of the spectrum than others. In the potassium cell the sensitiveness was greater for blue and violet radiation. Greater part of the light produced by the exciting lamp was therefore not utilized. The caesium cell, however, is highly sensi
T ’w etity six
KAELIN ELECTRIC CO.
Motor Specialists
Motor Generator Sets for Eliminating "B” Battery
Spare Generators on hand for Emergency Calls
Guaranteed Repairing on Motors and Generators
KAELIN ELECTRIC CO.
Phone WEstmore 2510 211 Venice Boulevard Los Angeles, California
(Continued From Page 18) differences as noted between the 242 and the 211E tubes are as follows: The new 242 has an impedence of 2500 to 4000 ohms, which is 500 ohms less than the 211E tube.
The new tube uses 314 amperes against 3.0 amperes of the 211E tube. A new feature of the new tube which will be greeted with loud hosannas by the radio hams is the fact that ERPI omitted the radio frequency choke on the 242.
The grid bias runs from minus 30 to minus 60 the same as the 211E. The filament appears to be “Thoriated,” which would account for its greater brilliancy when burning.
tive to radiation within the range produced most abundantly by the exciting lamp, the yellow, red and infra red, there being comparatively little blue or violet radiation.