. Practical wireless telegraphy; a complete text book for students of radio communication . othe higher frequencies than to those oflower pitch. Telephones of 75 to 150 ohms resist-ance, if used with the magnetic detector,the tikker, and the three element vacuumvalve gives good response, but other re-ceiving detectors, such as the crystal recti-fiers, require telephones of at least 2,000ohms resistance. Telephones of 15,000ohms resistance have been constructed butsuch a winding is not required for theaverage radio receiver. A telephone receiver possessing a notabledegree of sensitiveness has b
. Practical wireless telegraphy; a complete text book for students of radio communication . othe higher frequencies than to those oflower pitch. Telephones of 75 to 150 ohms resist-ance, if used with the magnetic detector,the tikker, and the three element vacuumvalve gives good response, but other re-ceiving detectors, such as the crystal recti-fiers, require telephones of at least 2,000ohms resistance. Telephones of 15,000ohms resistance have been constructed butsuch a winding is not required for theaverage radio receiver. A telephone receiver possessing a notabledegree of sensitiveness has been recently developed in the United States by T. essential parts of this receiver are indicated in the diagram, Fig. 19Sa, where a ringshaped horseshoe magnet with poles N and S is fitted with two U shaped soft ironpieces, P-1 and P-2. The telephone winding W, placed longitudinally between these polepieces, has a slot in the center in which is placed a soft iron armature balanced on thepivot P-3. One end of the soft iron armature is connected by the brass wire R to the mica. 195a, bj c, d. Construction and MagneticCircuit of the Baldwin Telephone. RECEIVING CIRCUITS, DETECTORS, TUNING APPARATUS. 169 or isinglass diaphragm M which is screwed under the receiver cap as in the ordinarytelephone. During the passage of a fluctuating current through the winding W the softiron armature A is thrown into vibratory motion and the vibrations transferred to prominent feature of this receiver is the fact that the armature A is under no magneticstrain until a fluctuating current flows through the winding W. The fundamental principle of operation is as follows: The diagram, Fig. 19Sb, showsthe direction of the lines of force of the permanent magnet through the pole pieces, andas will be observed the flux divides equally between both sides of the U shaped polesand continues through the magnet. Due to this division of flux, there is no strain on thearmature A, a condition just o
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Keywords: ., bookcentury1900, bookdecade1910, booksubjecttelegra, bookyear1917
