Radio age (May 1922-Dec 1923)

14 RADIO AGE— "THE MAGAZINE OF THE HOUR" New Stuff by Boy Readers By Edwin Nielsen DO YOU have trouble in .srettinploud signals on your crystal detector set? Why not use a crystal amplifier in one or two stages simply by connecting one or two crystal detectors in series with your original crystal detector, using an amplifying transformer and a 22-volt B battery as shown in the illustration. This will enable you to get loud signals where only weak ones were formerly heard, will greatly increase your receiving range and will enable you to use a loud speaker horn instead of your phones, thus allowing the whole family to listen in, where before only one could listen at a time. This idea had its origin in the brain of a South American amateur, who has organized the first if not the only Radio club in that part of the world. And I have tried this type of amplifier and had the signals far exceed my hopes in loudness and clearness of tone. To get good results it will be necessary to get very sensitive crystals and place the catwhisker wire on the most sensitive place that can be found, the crystals can be tested by connecting a buzzer, battery, a key and a coil of about 10 turns together, as shown in the illustration ; this coil is placed as close as possible to the tuning coil of the receiving coil and the key is pressed. This sets up miniature radio waves which are caught by the receiving coil and carried over to the detector where the crystal to be tested is mounted. The catwhisker is moved around until the best spot is found. The other crystals can be tested in the same way. If no buzzing is heard in the receivers while the crystal is being tested another crystal must be used. Beginners Need This A number of requests have come to the editor asking how the reader could secure the plans of a homemade receiving set published by the Bureau of Standards in Washington. The editor is in receipt of a letter from that department saying that, owing to the great demand, the department is unable to furnish any more free copies of the lessons, but will publish them as Bureau of Standards Circular No. 120, which may be secured by writing the Superintendent of Documents, Government Printing Office, Washington, D. C, and giving the number of the docu iiiiiiinHiiiiiiiiiiiifnii By Joseph Stelzer, East St. Louis, 111. THE rotary tuning coil shown in the one-column sketch gives the complete wiring diagram. The circle is cut from ^-inch stock, 1 inch wide, and well covered with insulation. It is then wound with No. 24 single cotton-covered wire so that the coils will lie flat. All of the arms are ^-inch square and are of brass. The supports are smaller in section. Slides are mounted on the ends of the long arms and are kept in place by set screws. The insulation on the wires is removed with a small piece of sandpaper pasted on a block of wood. This should be temporarily fastened to the revolving lever at the point where the contact is wanted; then the lever is turned until the insulation is removed. The wiring diagram shows the location of the tuning coil in the line. F.C ment as above. This article with illustrations was a feature of the May issue of Radio Age. Copies of that issue will be mailed on receipt of 25c in stamps by Radio Age. Red Gross Radio The American Red Cross is considering the use of radio as an aid in its emergency work. At the radio exhibition in Boston a radio set with a receiving radius of 2,000 miles was in operation for the reception of first aid calls, which were answered by nurses in attendance at the Red Cross booth in the exposition hall. Trying the Voice In an address before the Chicago Rotary Club, Morgan L. Eastman, with the aid of pictures and radio apparatus, showed how the voices of singers are tested before they are used for broadcasting purposes. Mr. Eastman devised a microphone, which was worked out by Westinghouse engineers, so arranged that a listener may determine .whether a singer in an adjoining room has a voice of the proper carrying quality. Mr. Eastman is in charge of the Westinghouse broadcasting station KYW on the Commonwealth Edison building, Chicago. BATTERY ^ e.oZ-'Z-'^^ (Tli'l'i-^ ffi COIL KEY ,^^^^ yiK<i> -> DETE CTOR o^ ^<r.-^Kc^-?:^^s A^Vu^'-" TWO SLIDE TUNING COIL AMPLIFYIINQ TRANSFORMER CONNECT FONES HERE IF NO AMPLIFYING IS DESIRED CONNECT HERE IF 2 STAGE. AMPLIFICATION IS DESIRED CONNECT PONES HERE IF I STAGE AMPLIFIER IS USED.