Exhibitors Herald World (Oct-Dec 1930)

November 29, 1930 EXHIBITORS HERALD -WORLD 41 w SOUND REPRODUCTION THE BLUEBOOK SCHOOL By F. H RICHARDSON BLUEBOOK SCHOOL QUESTION NO. 64. — (A) Explain in full detail, just what will be the effect, or the effects, of dirt, dust or electrolyte, or a combination of all three, on the top of storage batteries? (B) What is meant by "battery examination day," and what attention should the batteries have on that day? (C) Of what does a dirty battery job speak? ANSWER TO BLUEBOOK SCHOOL QUESTION NO. 44 The question was : Provided the plate be connected to the grid, is the grid an advantage or a disadvantage (and why) when the tube is used to rectify current? Explain just why the plate and filament of a tube act as a current rectifier. Is current rectified by a single tube direct current? THE following made good on this one — Gayle Grubaugh, Carl F. Daugherty, William Sidons, Karl Friederich, Thomas Dillon, Lester Van Buskirk, G. T. Baldy, Amos D. Grady, William Truax, Ben Edwards, William Cohlyn, F. T. Spencer, T. P. Kleine, George Lavenburgh, L. G. Sands, T. Brewer, Andy Kolby, M. Golding, R. L. Thompson, Harry Crowley, B. L. Sanderson, Frank Kelly, T. D. Collins, L. Pretzfield, A. C. Hahn, Billy Johnson, G. L. Doe, Alex Pyster, Ben Edwards, R. D. Gurley, William Dennison, Thomas Brewer and another who gave no name. There were many excellent answers. I have selected that of brother Daugherty for publication because of its clarity, correctness and conciseness. Daugherty says : "If a tube containing a grid is used as a current rectifier, the grid may prove to be an advantage if it is connected to the plate, because of the fact that the useful area of the plate will thereby be increased, since the grid itself then becomes a part of the plate. But if it is not connected to the plate, it is more than likely to detract from the efficiency of the tube, as it may collect a charge of its own, and thus interfere with the flow of the electrons. "The plate and filament of a tube act as a current rectifier because of one important fact, which is that the current can flow only from the filament to the plate. This is true, because electric current consists of small particles of negatively charged electricity, known as electrons, which are attracted by positive and repelled by negative. The filament, being heated and negatively charged with electricity, produces electrons. This the plate can't do since it's not heated ; also, because of the fact that it is positively charged during half of each cycle of the alternating current. The electrons, then, being attracted by positive, flow from the filament to the plate during the half-cycle in which the plate is positively charged. During the succeeding half-cycle in which the plate is negatively charged, the electrons, being repelled by negative, could not flow at all. It follows, therefore, that any flow of current through the tube could only be in one direction. "Current which is rectified by but a single tube is not true direct current. This is because only one-half of each cycle of the alternating current is able to pass through the tube, both the plate and filament being negatively charged during the other half. The result is a highly vibratory current, which uses only half of the total amount of power available and therefore is not a true direct current." Incidentally, one correspondent says, "Why do you never publish any of my answers, though my name almost always appears as having answered correctly." For the simple reason, my brother, that almost always there are many correct answers from which I must select one for publication. If they are all correct, then I must make my choice between them upon other points, such as neatness, conciseness, etc. For example, my old friend Budge, has apparently stopped answering very likely because, while he evidently expended much time in looking things up and preparing a thoroughly correct answer, still those answers were very seldom more correct than some others, and they were seldom worded in the best way for appearance in print. Therefore, while his answers were correct and were given due credit as being correct, they were not published. This "school" is being run for the benefit of those who follow it, and when you have done your best to prepare a correct answer and have sent it in, you have had all the possible benefit because you have studied and learned all you were able to on the particular point under discussion. Also, you have learned how to use your Bluebook in the best possible way. You really gain nothing from having your answer published. The "school" is valuable for you only in that it leads you to study and tells you wherein you have been right and wrong in your answers. ANSWER TO BLUEBOOK SCHOOL QUESTION NO. 45 The question was : Describe in detail the method by means of which two tubes may be used for rectifying current, and thus both halves of alternating current be made availableDoes the double connection (two tubes) produce direct "current? How is non-pulsating current derived from a two-tube recitfier? How would you clean the contact points of a rectifying tube? THERE were many excellent answers to this and many which were in need of considerable fixing. The following sent in replies that were passed as correct — Van Buskirk (very good, indeed), Frank Dudiak, Karl Friederich, Carl F. Dougherty, Gayle Grubaugh (also excellent), G. T. Baldy, G. L. Doe (very good), T. R. Davis, Theodore Rantzley, William Foster, S. L. Allen, Robert Cirker, Frank L. Lee, W. D. Arnold, A. D. Henley, L. Thomas, Bert Rindley, Henry Singleton, Phillip Arnold, Frank T. Simmons, T. R. Mathews, M. R. Harrison, George Thompson, Ben Edwards, Tyron Deffers, Bill Doe, Andrew Schafer, T. G. Bryan, L. Herman, T. Robert Rhodes, Sydney Crowley, Wilson Smith, Jacob T. Rudd, Ernest B. Black, John Erick, Andrew Hahn, Oliver Brady, David Fiegel, Robert Richards, G. B. Alexander and F. T. DuBoise. It was hard to select from the answers, but I think probably that of Carl Daugherty will perhaps serve a bit the best, because it is [Until further notice, all communicaions to this department should be addressed to F'. H. Richardson, 43-28 Thirty-ninth place, Long Island City, N. Y.] possible to reproduce the drawing without retracing it. (When drawings are sent, please make them in black ink.) Daugherty says : "Two tubes may be used in the following manner to rectify current and make both halves of alternating current available: "As may be seen in the accompanying illustration, the two transformers, Tl and T2, are connected through their primary windings with the 110-volt alternating current supply. These transformers are used to stepup and stepdown the current, Tl being used to supply the necessary high voltage to the plate and grid of each tube, and T2 being used to supply the necessary low voltage to heat the tube filaments. As may be observed in the drawing, wire C and wire A, coming from opposite ends of the secondary winding of 1M