Evening Star Newspaper, May 15, 1922, Page 19

Expert Advice on Radio No. 1.—How Radio Waves Carry Squnds. BY A’ HYATT VERRILL, Bxpert.on Radio Technology. We often read and speak of the alr being “full-of sounds” which we may hear by means of a radlo telephone re- celving set, but strictly speaking this 1s not the case. The air, or rather the ether, is full of wireless or radio waves carrying sounds, just as it is full of heat waves and light waves, which can also be made to carry sounds. Indeed, it was Prof. Alexander Gra- .ham Bell who first transmitted sounds ‘without the aid of wires, and in doing this used a wave of light. But because this is so we would not think of light waves as being audible, and it is just as erroneous to speak of making radio waves audible. Ordinarily, too, we think of radio*waves and light and heat waves as traveling through the air, but in reality the medium through which they travel is the invisible, colorless and almost weightless substance known as ether or luminiferous ether, which pervades the air, space and all known substances and objects. Once we real- ize this fact we cdn understand better why and how radio waves penetrate ‘walls, buildings and the insulation on wires. Perhaps the easiest way to under- stand the principles of radio or electro- magnetic waves is o compare the ether to a pool of water and the sending or transmission station to a stone thrown into the water. As every one knows, NNNNNN Fig 2 AN NN 72 g R w b - 728 when an object is cast into water it produces waves, which move away from the spot in every direction. Thus the muscular energy of your arm used in throwing the stone produces waves, just as the electrical energy of the sending station is necessary to start radio waves on their journey. Like Ripples on Pond. If there are bits of floating wood or bark upon the surface of the water or it grasses or reeds are growing in the pool, you will notice that the waves produced by the stone cause these objects to vibrate, but that the waves continue bevend them. In much the same way the radio waves, reaching an aerial or antenna of a receiving station, ‘set up vibrations or electro-magneétic waves in the wires but continue on- their way as before. You can also readily understand that by having a prearranged code it would be possible for two people to communicate by means of water waves, for, by throwing stones imto the water at certain intervals. the person on the shore would be able to understand the’signals by watching the waves. Of course, this would be a very crude and ' unsatisfactory means of communication, but it would be on the same principle as communicating by wireless teleg- raphy, for wireless telegrams are merely electrical waves sent out in broken or interrupted sequence rep- resenting dots and dashes and are reccived by other instruments which record or make audible these broken waves. Just as the water waves move up and down as they travel forward, so radio waves, which are known as “alternating currents,” move up and down or back and forth as they travel through the ether. This is fllustrated in figure 1, which repre- sents the flow of such an alternating current, while figure 2, shows the same wave broken or interrupted by the dot and dash signals of the key to_the sending instrument. Such waves, however, are of. very high frequency, or, in other words, they vibrate very rapidly, and as the human ecar cannot detect or record vibrations of ovef 10000 & second, means must be devised for reducing or cutting the waves down before they can be transformed into sound waves. Detector Cuts Waves. This is done by means of an Instru- ment called s detector, Which cuts the alternating currents in half by acting like & valve which allows the lcurren(s 0 flow In one direction but not in the other. Hence the wire- less wave shown In figure 1 would appear as in figure 3, after it had passed through the detector and the broken dot and dash wave, figure 2, would be like figure 4. But as these wireless electrical waves are fiever audible they must be transformed into sound waves In order to be heard, and this is done by an elec- trical-mechanical device known as the “telephone receiver.” Perhaps, at first thought, it might seem possible to connect an ordinary telephone transmitter to a wireless telegraph set and by talking into the instru- ment transmit the voice to a person at the receiving instrument. But with the old type radio telegrdph instrument this would have been im- possible, for the sounds or words would have been broken or inter- rupted and would have been received in fragments. In figure 5 the sound wave of a word s shown diagram- matically and such a sound wave as it would appear if carried by an in- terrupted wave Is shown_ in figure . Moreover, such waves as ‘sent by the old style spark-gap instrument were not continuous, as they ap- peared, but were composed of many independent or interrupted waves, and the modern practical radjo tele- phone was made possible by the dis- covery of means for sending unin- terrupted or continuous waves. This is done by the audion bulb or vacuum tube, and it was this simple but won- derful instrument which brought radio to its present state. Such a continuoys wave is represented by figure 7, and when such a wave is varied or affected, by a sound wave it is made serrated or uneven, as In figure 8, but is not broken. Therefore, such a wave, even when cut in half by the detector, may be transformed into sound waves and the original sounds exactly repro- duced. Compared to Phonograph. This may be clearer if we com- pare the wireless telephone to a phonograph. If the blank record with its spiral grooves is placed on the recording machine the needle on the diaphragm will vibrate and cut little depressions in the wax as a person speaks into the horn. Then, if the record is placed on an ordi- nary phonograph, the needle on the diaphragm follows these little depres- sions and causes the diaphragm to vibrate and reproduce the original sounds. Therefore, we may compare the radio waves to the spiral grooves in the wax record and the variations upon them, caused by music or Voices to the marks made by the needle. And we may compare the receiving station to the other needle which transforms the indentations In the wax to_sounds we can hear. Hence it is no more correct to think or speak of electrical or radio waves being heard than to talk of the inden- tations on a phonograph record being beard, for jus{ as the marks on the wax are made to create sound waves by mechanical means, so the variations of a wireless wave may be made to create sound waves by electrical devices in the telephone receivers. (Copyright, 1922.) (Tomorrow—How Detector Cuts Waves.) RADIO CONTROL TO DROP TICKETS FROM BALLOON { Mechanism Will Release Coupons for Radio Show When Key Is Pressed on Plane. During the New York radio which is to be held at the 7lst | ment armory the week of May 22, a large, free bailoon, controlled by wire- less, will fly over the city, dropping some passes for the show and a coupon which will entitle the finder to a re- ceiving set. Arrangements were completed for this test of remote control last Tuesday between the show management and Maj. C. Anderson Wright of the avia- tion division of the New York police department. The balloon will be launched and at the same time a police airplane will ¥take off”” for the dem- onstration. Suspended from the balloon will _be ~radio-controlled. mechanism which will release the tickets when the airplane pilot presses his key. The demonstration, which is in line with recent successful experiments con- ducted by Army and Navy aviators, will be the first of its kind supervised and conducted by civilian operators. MADE BISHOP OF PINARE. ROME, May 14—Mgr. Guglielmo Piani, the newly appointed apostolic delegate to the Philippines, has been consecrated Bishop of Pinare before starting for the Philippines. show, Regi- THE FIRST WE GET THE NEWS REPORT =THEN THME MARKET REPORT ~THEN ‘THE AGRICULTURE REPORT 19 THAT'S A NEwW CNE ON ME It MUST BE THE POLICE REFORT INSTRUCTOR NEW YORK. AS THE REASON FOR HIGH Those who have purchased head telephone receivers or who have contemplated doing so' have prob- ably wondered why the high re- sistance phones were considered more sensitive than those of low resistance. As a first’ thought it would appear that high Pesistance is the very thing that should be avoided. The pull on a received diaphragm depends upon the strength of the magnetism at the poles (or ends) of the magnets. This magnetic strength, or pulling power, depends upon the current flowing through the magnet windings and the nupber of turns of wire in the wind- Ings. Usually the current passing through the windings is very weak, and not much pulling power would be produced if only a comparatively few turns of low resistance wire were used. A large number of turns of low resistance wire would occupy more space than would be conven- fently available because the low re- sistance wire would necessarily have comparatively large diameter. If finer wire, say around No. 40, were used, considerably more turns would ARRADAL Y.M.C.A. RADIO ScHOOL RESISTANCE RECEIVERS. be wound upon g moderate size bob- bin. And | the current is very weak. But the more turns which are wound on the bobbins the higher the resistance of the magnet windings. 8o high_re- sistance windings mean more séfisi- tive receivers, not so much because of the Increased number of turns of wires. It will not do, therefore, to use wire of high resistance, such as German silver, and receivers wound with such wire are just about value- less. The wire should be copper of good conductivity. It is often said that high resistance receivers should be used with high resistance detectors, such as crystals and vacuum tubes. This is because a high resistance detector cuts down the current strength and makes necessary, therefore, many turns of wire in the magnet windings to pro- cure the required magnetic strength or pulling power. If a low resistance detector were used more current would flow In the circuit, other things being equal and a lesser number of turns would be satisfactory. New Apparatus and Devices () By Ralph Brown, Radio Enginee A COMPLETE V. T. DETECTOR UNIT There are many radio experimenters who require a complete vacuum tube detector unit so arranged that it can be used in a circuit laid out for test- The unit illustrated appears to ing. be well suited to such a purpose, and, when desired, can also be mounted within a cabinet. Two screws only are necessary for cabinet mounting. The unit “is complete with tube socket, filament rheostat. mica dielec- tric grid condenser and a mica di- electric by-pass condenser for shunt- ing across the plate battery and head telephones when required. As shown in the lllustration, the rheostat is very simple in <construc- tion, the colled resistance wire being supported on the edge of a circular plece of insulating material. The edge of the circular plece is grooved so that the coil cannot slip out of post for the plate, grid and fllament connections is plainly marked so that wiring may be done quickly. A rheostat knob is provided, and a dial may be easily asttached when desired for panel mounting. An_amplifier unit s also made, which is quite similar to the detec- tor unit, except for the addition of a shell type amplifying transformer. In this unit the transformer s mounted directly behind the tube socket on the same shelf. BY RADIO TODAY NAA—Naval Radio Station. Radlo, Va. 10:30 a.m.—Meteorological report on 5,950 meters of aro transmitter. 12 noon and 10 p.m—Time signal, orders. 10:30 p.m.—Naval press news. Wave length, 2,650 meters. - WWX-=Post Ofice Department. a.m.—Weather report for the Dis- of Columbia. Pennsylvania, Ohio, 10 trict of the resistance itself, but because | followed by weather report and ship t is a large number of|announced; “Poet and Peasan wire turns which Is necessary, since |1 (Von Suppe); | WIZ—Newark, Maryland, Virginia and West Vir- ginla. 10:30 l.mm—Ml‘ri(“ethrm;n (fruit and vegetables) on 1, meters. 530, ..:)15 and 3:30 pm—C. W. marketgram telegrams on 1,980 me- ters. 5 p.m.—Wholesale dairy report on 1,160 meters, by radiophone. 7:30 and 8 p.m.—Market report on 1,160 meters, by radiophone. :50 p.m.—Weather report. ‘WMU—Doubleday-Hill Electric Co. (360 Meters). 4:30 to 5:30 p.m.—Base ball " part “Novelette,” p! “Some Sunny Day espri Sici (Schumann); trot (Irving Berlin) ani,” soprano (Verdi (Puceini); “Who,” fox trot (Fried- land); “Afda,” tenor (Verdi); “Ro- mance,” piano (Faure); "“Stealing, fox trot (Sullivan); “Poet and Peas- ant,” part 2 (Von Suppe) Sail,” plano_(Bendel fox trot (Romberg “My Honey's Lovin' Arms” (Meyer); “Turkish March,” piano (Beethoven) She Loves Me, She Loves Me Not” (Ed Wynn)~ “Narcissus,” piano (Nevin); base ball scores announced. WPM—Thomas J. Willinms. Ine. 8 p.m.—Talk, C. E. Achstetter. deputy fire marshal of District of Columbia; soloists, Mrs. Harrle White, soprano; Mrs. Anna Brett Summy, contralto; Mr. Kenneth W. Ogden, tenor; Howard Blandy at the piano—"Ave Maria” (Hom Caud), “Indian Love Lyrics” (Woodford-Finden); duet, so- prano and tenor. “Where My Caravan Has Rested” (Lohr); Eastern Daylig! Deduct One Hour). 6 p.m.—"Business and Industrial Conditions in the United States,” as observed by the National Industrial Conference board. 7 p.m.—Stories from St. Nicholas Magazine, courtesy of the Century Company. 7:30 p.m.—"“How to Get a Job,” by B. W. Ormstead. 7:45 . to 9:30 p.m.—Concert by the orchestra and choral clubs of the Young Women's Christian Associa- tion of Newark; address by Mrs. Frederick Paist, president of the na- tional conference recently held at Hot Springs: “What the Y. W.C. A. Means to Me.” in poems and prose, by four members: negro spiritual songs, by a double quartet of colored girls from the Sojourner Truth branch. 9:30 p.m.—Recital by Pauline Jen- ings, soprano. - 9:52 p.m.—Arlington time signals. SYN—National Radlo Institute (360 Meters). 6:30 to 7 p.m.—Radlo spark code. ‘WVP—Signal Corps, (360 Meters). 8:50 p.m.—Instruction in radio. 9 p.m.—Recital. WWZ—Wanamaker's, N. Y. (36D Meters). 1:40, 5:40 and 10:30 p.m.—Music and children's stories. U. 8. A. KDKA — Westinghouse, Pittsburgh (360 Meters—Eastern Standard Time). 6 p.m.—Weekly review of business conditions. 7 p.m—"The Clerical Worker,” by Miss Edna Graham, in charge of women's employment, Westinghouse Electric and Manufacturing Company, East Pittsburgh. “Teaching as a Vo- catfon,” by Mrs, Allce Carmalt, board of education, University of Pitts- burgh. 8 p.n.—Varlety off vocal and instru- mental selections by members of the Glee_Club_of Pennsylvania College for Women, Mabel Davis Rockwell, director. WEZ—Westinghouse, Springfield, Masw. (360 Meters—Eastern Standard Time). Bise ball scores. Musical program by John Myers, violinist, and Clara Morgan, pianist. KYW-—Westinghouse, Meters, Central Chicago (360 Daylight-Saving Time, Same ns Eastern sz-uudl ports, financial and base ball returns. Time). 7 1 7:15 p.m.—~Base ball report, chil- 28 @m—oOpening market quota-|dren’s bedtime story. ons, 2go - Board. of Trade. 8 to 9 p.m—Program of music by 10 'am—Market quotations, Chi-|cainerine Taneny, soprano. n;dch:I'- cago Board of Trade. Quotations||i, Menkes, accompanist; Charles M. every half hour thereafter until1p.m. |y, bass, and Beulah Taylor Por- 1 p.m.—Closing market quota- | ey ist, and Adymae Par Chicago Board of Trade. : SN bel m: haway, E 0 violtnist, and Mubel 2:15 p.m.—News and market re- A e [Lyons, pianist. 3 pm—American and National S League base ball team line-ups; prog- WGI—Medford, Hillside, Manx. Tess of games every half hour there- | (360 Meters, Eastern Standard Time). after until close of all games. 2:35, 3, 7:30 and 7T N 4:15 p.m.—News, market and stock | 2% % o e and reports. reports. | § p.m.—Lectures and music. 6:30 p.m.—News, final market re- . L. Offutt, Jr. | Cashier i | ‘7 of 3 per cent. e Distri¢t National Bank If it’s true that— “It takes money to make money’ what better argument do you need to take the necessary steps right away, on THIS PAY DAY, to start that nu- cleus of the competency you hope to assemble? There’s only one absolutely sure way—and that’s through systematic saving. Get that habit, foster it with anything like persistency—and you’ll soon have the money to do with. Thrift isn’t stinginess. ness—taking care of the future needs and ambitions out of the.surplus of the present. A Savings Account is the best incentive to save; and we’d like the privilege of opening one for you. While the money is in our keeping we pay interest at the rate For the accommodation of the Govern- ment employes, who under the daylight saving plan will not have the morning hour opportunity to attend to their banking, we shall keep one window open until 4 o'clock for the acceptance of deposits and cashing of checks. ; Vice Presidents | W. P. Lipscomb | Lewis Holmes C. J. Gockeler | 1406 G Street b It’s just simply judicious- Why you‘ should touch-test record cards Run your finger along the edge of any L. B. Card. Notice the smooth ‘“feel.” No fuzz; no rough spots; no saw teeth. Sharp? Yes. But it won’t cut. Smooth? 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B. Cards a quality reputation as well as an enviable preference in govern- mental departments. L. B. Cards are Item 1460 on the' General Supply Schedule. Phone, write or call for sample cdrds and copy of “Card and filing supplies.” fi?&%firflg kerchief and out-wears > Libral'y /Burea.,ll Founded 1876 Filing cabinets “half a dozen ordinary collars. T Nitie styles and heights in quarter mmm»nmfiym PIPER BUILDING, BALTIMORE Card and filing systems t _R.0. SAUNDERS, Manager Telephone: Main 1188 743 Fifteenth Street, N. W., Washington, D. C. Salesrooms in 49 leading citles of the United States, Gmtnrlnhund.rm and steel 44 Cgac lo made } WMC«“::Nn!d‘ ital Cigar and Tobacco Co. Washington, D. C.