US879643A - Telephone-circuit. - Google Patents

Description

,643. PATENTED PBB.18`, i908 C. M. JACOBS @L W. J. THoRRoWGoou TELEPHONE CIRCUIT.

APPLIGATXON FILED 0011.12.1906.

l has phone receiver does not respond to currents `pore winding of th parallel, the object .regarded from the point of view of telephone invention.

' CHARLES-MARKS JAcoBs. or

READING, AND WILLIAM JonN v'rnonnoweoon or WIMBLEDON PARK, ENGLAND,

- TELEPHONE-CIRCUIT.

To all whom it may concern: I Be it known that we, CHARLES MARK JA- cons, electrical engineer, and WILLIAM -JOHN Tnonnoweoon, telegraph engineer,'both subjects of the King of Great Britain, resid- Ing, respective] ,at St. Cuthberts, Alexan- .a Road, Rea in in the county of Berks, England, and 2 Waldemar road, Wimbledon Park, in the county of Surrey, England, have invented certain new and. useful Improvements in Telephone-Circuits, of which thefollowing is a specification, (for which we have applied for a patent in Great Britain, dated the 13th January, 1906, No. 997.)

In a known constructionv a telephone receiver is wound with a phonopore'coil, which serves as a condenser of very small capacity, so that whenv the receiver is used on an unbalanced circuit, the disturbing effect of currents of low frequencies is not perceived in the tele hone. Inusing this tele henereceiverit heen connectedwithits p onopore coil in series with the secondary of the telephone transformer, an arrangement which is disadvantageous in that the resistance of the phonopore coilsv enfeebles the currents induced in the secondary.

By the resent invention the secondary of the telephone transformer `and the phonoe receiver are arranged in being to reduce considerably or to eliminate the effect in the telephone receiver ofcurrents of low fre uencies and to insure that the volume of t e telephone currents through the telephone relceiver shall be a maximum. l

The fact that a phonoporically wound teleof lower than telephonie frequency is probably de tothe fact that such a telephone receiver acts practically as a condenser of small capacity, and on this account it becomes necessary 1n orderto obtain a maximum effect Specification efLetters Patent. 'Appiicaion nea amber 12.1906. 'sentira 338.679.

vthe latter.-

in the receiver with` telephonie currents that the terminals of the telephone receiver shall he connected with such points of the circuit as have a maximum di erence of potential currents. n v The accompanying diagrams illustrate the Figure 1 shows the arrangement of a two wire used for telegraphic purposes. Figs. 2

Patented Feb. 18, 1908.

and 3 show alternative arrangements of an intermediate tele hone. Fig. Sashows the arrangement of Fig.. 1 applied to an intermediate station.

In each of these arrangements a is the hat'- tery, Z2 the transmitter, c the primary of the telephone transformer and the secondary of this transformer connected in the line Z. Referring to Fig. l the phonoporically wound receiversof the tele hones at stations A and A are connected in eak to earth E at the points i', and of the line Z. Owing to the self-induction ofthe secondaries d the potential of the telephone currents impressed upon the circuit by means of the primaries c and secondaries d has an appreciable drop through The phonoporic receivers g bei connected in leak to earth at the points t' an y' are therefore-connected'to points of maximum potential so far as concerns telephone currents impressed by means of the primaries c and secondaries The impedance offered to telephone currents by the secondaries Z being a reciable, -while the receivers g offer practica y no impedance to telephone currents, more kof the telephone currents impressed on -the circuit at A or A will pass through the receivers g than through the secondary at A or A. The condensers f, which have considerable capacity, are connected in leak to earth at the terminals Zt and Zc of the .secondaries Z so that if the line Z has considerable ohmic resistance or impedance to the leftof Za, or the right of Zr, telephone currents can get to earth at the points Zi and Zc and not suffer attenuation through having to traverse the y.Whole length of the telegrzphic line Z.

n the case of an intermediate telephone the receiver maybe in leak on the side of the secondaryfof the telephone which is nearer to the stationI with which the user 1s speaking, J

for convenience,` therefore, there may be a receiver on each side 'of the secondary or the receiver may be provided with a switch for connecting it with either side as shown in Fig. 3a. Fig. 2 shows an arrangement Whereby one receiver only is sufficient at an intermediate stationwithout a switch being necessary. In this case the terminals of the receiver g are connected in shunt across the lterminals of the secondary al. The impeance to telephone currents being greater through the secondaryd than through the reduction coil is not included directly in the line circuit but is connected in leak from line to earth through a condenser, the latter being necessary in order to prevent telegraphic currents from the instruments such as m, n, in Fig. 1 passing directlyr to earth at this point. The phonoporic telephone receiver is also connected [in leak from line to earth, the two arrangements consequently being in shunt with each other. Although the secondary d and condenser f are in shunt with the phonoporic telephone receiver g, they do not materially affect thev volume of the received telephone currents on account of the self induction of the secondary.

Having thus described the nature of this invention and the best means We know of carrying the same into practical eiiect We claim: f I 1. In a system for eliminating or reducing the infiuence of disturbing currents on telephone circuits7 the combination of a telephone transformer and a phonoporically Wound receiver, thevlatter being connected across the terminals of the secondary Winding of the.

more of the telephone currents im.

transformer, the 4said secondary Winding being -directly in the line.

2. In a system for eliminating or reducing the influence of disturbing currents on telephone circuits, the combination of a telephone transformer, aphono orically Wound receiver and ya condenser, t e said receiver and condenser being connected in series with each other across the terminals of the secondary Winding of the transformer and having their intermediate point connected with earth.

3. In a system for eliminating or reducing the influence of disturbing currents on telephone circuits, the combination of a telephone transformer, a phono orically Wound receiver and a condenser, t 'e said receiver and condenser being connected in series with arywinding of the transformer and having their `intermediate point connected with earth, and the said secondary Winding being .connected directly-in the line.

In testimony whereof We have signed our names to this speclfication in the presence of two subscribing Witnesses.

' CHARLESv MARK JACOBS.

WILLIAM JQHN THORRWGOOD.

Witnesses:

JOSEPH MILLARD, WALTER J; SKERTEN.

each other across the terminals of the second-

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