American telegraphy and encyclopedia of the telegraph; systems, apparatus, operation by Maver William jr

Author:Maver, William, jr. [from old catalog]
Language: eng
Format: epub
Tags: Telegraph
Publisher: New York, Maver publishing company
Published: 1909-03-25T05:00:00+00:00

WHEATSTONE RECEIVER—RECORDING PARTS.

Wheel w is also placed outside of the box and is rotated by the shaft n, which latter is operated by the clock-work within the box. The lower portion of w revolves in an ink-well, v, attached to the frame-work of the receiver, as seen in Fig. 229. The paper ribbon passes in proximity to the edge of disc p, but does not touch it. It, at times, however, comes so close thereto that it leaves an ink mark on the paper and this record is a dot or dash corresponding to the character transmitted from the sending; end. As, by this arrangement, friction is avoided, it will be readily understood that a, much more sensitive receiving relay may be employed than would be the case otherwise. The manner in which the characters are caused to be imprinted on the paper will be described presently. The polarized relay consists of the permanent magnet pm, Fig. 2^9, electro-magnets em, with two bobbins opposite each other, only one of which is shown here; the near bobbin being removed to show the armatures a, a', more clearly. Armatures a,a' are rigidly attached to the axle a:,and at the point of junction

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with the axle they fit loosely into a curved notch in the ends of the permanent maernet. Thus the ends of each armature between the pole pieces of the electro-magnets are " inductively" magnetized to opposite polarity. For instance, that at a would be north; that at a' south. The coils of the electro-magnet are so wound that the pole-pieces facing one another are of opposite polarity. Thus each armature is attracted by one and repelled by the other pole-piece, and it also follows that both armatures will tend to move in the same direction when current flows in the coils of the electro-magnets. The axle x is loosely pivoted on suitable bearings within the box. At its upper end it is provided with an extension e, as shown, which does not extend outside the box. This extension is given an upward turn at e', sufficient to bring it within the range of the shaft b. There is a notch in e' in which b rests very lightly.

A current intended to record a dot or dash on the paper is termed a " marking " current; one that is intended to permit a space on the paper, a " spacing " current When a marking current is transmitted the armatures move slightly, their motion being very limited, in a direction which turns the axle x and, consequently, moves the extension e towards the paper, and a dot or dash is recorded. When a spacing current is sent the armatures reverse their positions and the disc is withdrawn from proximity to the paper. Thus at each change in the direction of the current, .which is brought about by the action of the transmitter, the armatures are oscillated, and with each oscillation the disc p is either caused to approach or recede from the paper.

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