Robison's Manual of radio telegraphy and telephony for the use of naval electricians (1918) (14753122861)

Identifier: robisonsmanualof00robirich (find matches)

Title: Robison's Manual of radio telegraphy and telephony for the use of naval electricians

Year: 1918 (1910s)

Authors: Robison, S. S. (Samuel Shelburne), b. 1867 United States Naval Institute Todd, David Wooster Hooper, Stanford Caldwell

Subjects: Telegraph, Wireless -- Handbooks, manuals, etc Telephone, Wireless -- Handbooks, manuals, etc Radio -- Handbooks, manuals, etc

Publisher: Annapolis, Md. : The United States Naval Institute

Contributing Library: University of California Libraries

Digitizing Sponsor: MSN

Text Appearing Before Image:

ce ofthe person speaking. The ordinary receiving circuit having a crystal orelectrolytic detector serves as well for undamped oscillations as forgroups of wave trains, transforming the modified oscillations into humanspeech in the receiving telephone. The limit of mechanical or air vibrations recognized as sound is be-tween 30,000 and 40,000 per second. Although the undamped oscilla-tions are of a much higher frequency and therefore produce no sound inthemselves, modifications of the amplitude of successive waves may be ofsuch a nature as to produce sound by slower variations in the rise and fallof the received current. The transmitting telephone may be in the arc circuit instead ofthe aerial as shown, or it may be inductively connected to either the openor closed circuit. There is as yet no standard practice. The telephonetransmitters are specially constructed to stand the voltage and currentinduced in the aerial or in the closed circuit. MANUAL OF RADIO TELEGRAPHY AND TELEPHONY. 127

Text Appearing After Image:

Fig. 62d.—Radio Telephone Set. 128 MANUAL OF RADIO TELEGRAPHY AND TELEPHONY. LIMITATIONS ON WAVE LENGTHS. 184. A certain amount of inductance is necessary in the closed circuitin order to transfer energy to the open circuit, whether the circuits aredirect or inductively coupled. Since condensers of any desired capacitycan readily be obtained, it is easy to make the closed circuit any electricallength we desire. There is, however, a lower limit to this, depending on the material andarrangement of the condenser and leads. Other things being equal, thelarger the capacit)^ the longer the connecting leads; and the shortestwave length that can be obtained for a given capacity is that found whenthe leads from the condenser are connected in the most direct manner tothose from the closed circuit and spark gap. The standard wave length for ships and shore stations, using dampedwaves, was first set at 320 meters. It is now 600-1000 meters for ships.Much longer wave lengths are used for undampe

1918 books book illustrations telephony history of technology high resolution images from internet archive

1918

University of California

http://commons.wikimedia.org/

public domain