US1749825A - Telegraph system - Google Patents

Description

March 11 1930( D, P, LQY 1,749,825

TELEGRAPH SYSTEM Filed May 24, 1928 INVENTOR ATTORNEY Patented Mar. 11, 1930 uNrrsn STATES PATENT OFFICE DONALD P. LOYE, OF BROOKLYN, NEW YORK; ASSIGNOR T AMERICAN TELEPHONE AND TELEGRAPH (I1OIYIIPAZBTY, A CORPORATION OF NEW YORK TELEGRAPH SYSTEM Application filed May 24,

This invention relates to telegraph systems, and more particularly to improvements in telegraph line terminal circuits for indicating at the telegraph board whenever the polarity of the current in a subscribers loop i printer in the spacing condition, or in a condition unresponsive to signals, although no indication might be had at the telegraph board at the central oflice that the signals were not being properly received. While the re- 1 versal of the loop current might be particularly objectionable in the case of printing telegraph apparatus, it is pointed out that such reversal of the loop current might be objectionable in many other instances where 'i the operation of other apparatus in the loop was dependent upon current of a certain'polarity.

It is the primary object of the arrangements of the invention to provide a device so asso ciated with the telegraph line terminal at the central office that it will operate whenever the polarity of the current in a subscribers loop associated therewith is reversed and will operate a signal at the central otfice, 36 whereby the attendant may be notified that conditions are such that the subscriber is not receiving the signals. Other objects and features of the invention will appear more fully from the detailed description of the invention hereinafter given.

The invention may be more fully understood from the following description, together with the accompanying drawing, in the figure of which is shown a circuit diav -3 gram illustrating a preferred form of the invention.

In the drawing is shown a section 1 of a telegraph line terminating at a central ofiice and controlling the receiving relay 2. The

I spacing and marking contacts of the receiving 1928. Serial No. 280,270.

relay are shown associated with the sources of current of opposite polarity 3 and 4. A break relay 5 and a sending relay 6 are shown. The sending relay 6controls, in effect, a short circuit 7 to be closed across the output of the oscillator of carrier frequency utilized for sending. This apparatus is not shown. A key 8 may be included in the circuit. As the above described apparatus is well known in the art, no further description thereof will be give I The telegraph line terminal apparatus includes a-number of jacks of which the jacks 10 and 12 are illustrated. The subscribers loopcircuit may be traced as follows: from conductor 9, contacts of jack 10,1eft-hand winding of relay 11, upper contact of jack 12, conductor 13, winding of polar relay 15 in the printing telegraph apparatus 14 at the subscribers station, conductor 16, lower contact of jack 12, conductor 17, right-hand winding of relay 18, and right-hand winding of relay 11, to battery 19 and ground. The

vrelay'll is the customary type of relay associated with the telegraph line terminal and I6 maybe operated by the subscriber unbalancing the circuit by switching a key, thereby grounding his loop circuit. The operation of relay 11 will close an operating and looking circuit from battery 23 for relay 20, which is released as soon as an attendant plugs into the jack 10 to answer. The operation of relay 2O will'close a circuit 24 from battery 23 to light the signal lamp '22. As has been pointed out, this means of signaling is provided so that the subscriber may signal the central office from his station, if desired, and is part of thecustomary apparatus associated with thetelegraph line terminal apparatus. The apparatus 14 in the subscribers loop has been referred to as printing telegraph equipment including a polar relay 15. This is for purposes of illustration only, and it is to be understood that the arrangements of the invention may be utilized in instances where the subscribers loop includes other types of apparatus depending in their operation. on current of a certain polarity.

It will be seen that if the polarity of the battery 19 should be reversed, the polarity 100 of current in the subscribers loop would be reversed and the polar relay apparatus there;

in would not respond properly. It is pointed out that certain telegraph line terminal circuits are known as east telegraph line terminals and certain others are designated as west telegraph -line terminals. It is customary for the battery corresponding to battery '19 o to be of" one polarity in the case of east apthis invention, there is provided a relay 18 not receiving signals. :10

have been disclosed asembodied incertain paratu-s and of another polarity in the case which will have one ofits windings in series in the loopjcircuit. The other winding will be included in circuitwith a battery arrangedv to furnish currentopposed and equal inmagnetic effect to the normal loo-p current through the-otherwindingp The relay 18--is adjusted to operate, it the currents in the biasing and loop windings of the relay are aiding-,with

approximately one-half normal loop current. With .this arrangement, the relay will not operate when either marking or spacing signals .are being received, provided the loopcurrent is in the correct predetermined" condition. If, however, the loop currentshould 'be'reversedidue, for. example, to an emergency battery tap of the wrong polarity being 'patchedtinto the circuit,or for any other reason) the current through, the loop winding of relay 1'8-will reinforce the current through the biasingwinding of the relay and cause it to operate. The operation of relay=l8 will connect battery 23 overthe contact of relay ing means at said central oflicecontrolled by said relay means.

2. A telegraph line terminating at a central oflice, aloop circuit for extending said line, a relay at said central otfice having a line winding in series with said loop circuit and a holding winding in a separate circuit, said windings being arrangedvto have oppose ing efiects when the loop current is in normal 7 direction, and signaling means atsald central office controlled by the operation of said relay.

3. telegraph line terminating at a central office, aloop circuit for extendingsaid line, a relay at said. central oflice responsive to a change in the direction of current flow in said loop circuit, and signaling means at said central ofiice controlled bysaid relay means, said relay: having a line winding in series with said loop circuit and a holding winding having batteryjcurrent opposed and equal in magnetic efi'ect to .the' normal loop current in said line winding and said relay being adjusted to operate if the currents in the: holding and loop windings are aiding with approximately one-half normal loop current strength. c In testimony whereoiQ I have signed my nameto this specification this 21st day of May, 1928.v

18 to conductor 24 and to the signal lamp22,

thereby operating it. This-will notify the operator at theicentral office of the fact that the loop current has been reversed from its proper condition andthat the subscriber is While the arrangements of the invention specific arrangements which aredeemeddesirable, it is understood that they are capable of embodiment in many and other widely varied forms'without'departing from the spirit of the invention a s' defined by the appended 7 claims;

What is claimed is:

1. A telegraph line terminating at a cen- DONALD- P. LOYE; V a

tral otfice,.a loop circuit for extending said "line, relay means in said loop circuitfat said central .oflice' normally unoperated by the 7 transmission of signals over said loop circuit but responsive to a change 1n the directlon of current flow insaid loop circu t, and signal-

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