Exhibitors Herald and Moving Picture World (Apr-Jun 1930)

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34 EXHIBITORS HERALD-WORLD May 10, 1930 w SOUND PICTURES THE BLUEBOOK SCHOOL By F. H. RICHARDSON BLUEBOOK SCHOOL QUESTION NO. 50. -Do „oi8y amplifying tubes give trouble anywhere except at the first stage of amplification? How would you make a test in case you had suspicion that a tube was noisy? What various troubles may loose connections, etc., in the batteries cause? ANSWER TO BLUEBOOK SCHOOL QUESTION NO. 41 THE QUESTION WAS: What is the speed of electrical action as compared with the speed of light or sound? Docs any ordinary incandescent lamp filament throw off electrons? Describe the action of filament, plate and grid, in detail. Upon what will the flow of electrons from filament to plate be directly dependent? THERE were some really surprisingly excellent answers to these queries. Also, there were a great many which, I think, could be improved. The following have, to date, sent acceptable replies: G. L. Doe, Charles Bannock, Leslie Yates, Harlan B. Fox, Carl F. Dougherty, Phillip Mason, Gavle Grubaugh, Max Olson, Peter Itt, B. Caldwell, T. R. Roand, Leroy Hicks, A. McClinock, T. R. Bankerton, R. O. Hayes, LeRoy Hicks, L. D. Schofield, R. L. DuBois, J. R. Malley, Thomas Allen, G. Cuter, Albert Hickson, William Peterson, A. D. Henley, H. M. Johnson, S. M. Johnson, P. T. Harrington, R. T. True, F. T. Spencer, John Bates, Albrey Cook, William Clausener, B. R. Hodson, Frank L. McAndrews, Stuart Klein, Andy B. Horton, Dan Uhlman, P. R. Kingston, Andrew Carroll and Bill Doe. After some deliberation as between the replies of Gayle Grubaugh, Bill Doe, R. L. Doe and T. R. Roand, I have selected the answer of the later as a bit the most complete. Roand says : “The speed of light is well known. It has been measured with at least tolerable accuracy. It is 186,000 miles per second, or 11,160,000 miles per minute. Sound travels at the rate of approximately 1,100 feet per second. As to the speed of electrical action through metallic conductors, I haven't heard of any accurate measurements. I have heard it said that it will travel around the world in about two and one half seconds, but never have I seen any statement as to the mileage of the circuit, which might, of course, vary widely, according to the route pursued. “The speed of radio emanations is, we are told by the lofty brows, the same as that of light, which is 186,000 miles per second. “The speed of light as compared with radio emanations is equal, while the speed of radio Send Answers Early Please send your answers to the Bluebook School questions as soon after publication of the questions as possible. Always there are a lot of late answers and I must either not give credit to those which are correct, or I must run their names in the next issue, which is more or less of a nuisance. Please try to be as prompt as you can. 1 am' arranging to give you more time, as you may have noticed when I ran questions without answers. Another thing: Always put the nmber of the question answered at the head of the answer. That is quite important in avoiding confusion in the filing of the great number of answers received. — F. H. R. emanations and light, as compared with sound, is as 186,000 miles per second is to 1,100 feet per second, with the notation that sound speed may vary as between 1,040 and 1,100 feet per second under varying conditions of atmosphere and temperatures. “Yes, every incandescent lamp filament emits or throws off electrons. Being uncontrolled (Page 1,028, Vol. 3, Bluebook) the electrons thrown off by ordinary light bulbs cannot be Prison Has Sound Films Every Week (Special to the Herald-World) McNEIL ISLAND, WASH., May 6. — The United States Penitentiary here is celebrating its first year with talking pictures. According to Fred E. Peters, editor of “The Island Lantern," the educational program offered to the prisoners is getting countless of comments. Pictures are shown once a week, the films coming from the Northwest Film Board of Trade. put to use as are the electrons emitted by the radio tube filament. “The filament of an amplifying tube is heated by current from a suitable storage battery. Its potential is negative. It sends out minute particles of electricity called electrons, which are negatively charged. Near to, but separated and insulated from, the filament is a sheet or plate of metal. This plate is connected with the positive potential of a storage battery, the negative side of which is connected with the filament. The circuit thus formed is broken by the space between the filament and plate, which is a perfect insulator so long as the filament is cold. “When, however, the filament is heated, electrons flow and are attracted to the plate by its positive charge. They form a sort of conductor (so I understand it) over which the current of the other battery flows from, or rather through, the filament, across to the plate, whence it returns to the battery through its appointed path. “Between the plate and the filament is, however, a sort of wire lattice called the ‘grid,’ which is connected with a battery called the ‘C’ battery, which supplies the negative bias necessary to its operation. In addition to this, the grid is connected into the output circuit of the p. e. cell circuit, the voltage of which is governed by the amount of light entering the cell from the film sound track. This latter causes the voltage of the grid to vary with inconceivable rapidity, and in accordance with the variations in light strength representing variations in sound. “Now, this current from the B battery must pass through the ladder-like grid, hence since the plate is negatively charged, its ability to attract the current, which circulates through the horns, will depend upon the opposition set up by the negatively charged grid — the amount of charge it carries from one ten thousands of a second to the next, which answers the last end of the question.’’ There, gentlemen, that is from a St. Louis projectionist who, you may take it from me, is not permitting his brain to go to sleep on sound. My compliments to him. The St. Louis local has some most excellent projectionists.