US1008313A - Fire-alarm system for telephone-exchanges. - Google Patents

Fire-alarm system for telephone-exchanges. Download PDF

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US1008313A
US1008313A US48798009A US1909487980A US1008313A US 1008313 A US1008313 A US 1008313A US 48798009 A US48798009 A US 48798009A US 1909487980 A US1909487980 A US 1909487980A US 1008313 A US1008313 A US 1008313A
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circuit
telephone
spring
signal
fire alarm
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William L Denio
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    • HELECTRICITY
    • H04ELECTRIC COMMUNICATION TECHNIQUE
    • H04MTELEPHONIC COMMUNICATION
    • H04M11/00Telephonic communication systems specially adapted for combination with other electrical systems
    • H04M11/04Telephonic communication systems specially adapted for combination with other electrical systems with alarm systems, e.g. fire, police or burglar alarm systems

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  • My present invention relates to fire alarm systems which are adapted for use in localities, such as cities, provided with telephone exchange systems and'it has for its primary object the combining with a subscribers telephone circuit, of a fire alarm signaling or calling instrument which when set into operation either automatically or manually will transmit to the exchange operator, in addition to the impulses indicating the number or code signal of the instrument, other impulses which vibrate the diaphragm of the central ofiice operators telephone receiver for the purpose of indicating audibly the operation of the signaling mechanism.
  • My invention comprehends the arrangement of parts whereby the operation of the signaling apparatus may be immediately recognized by the telephone operator as distinguishing the code signal of the fire alarm apparatus from line disturbances such as an intermittent ground applied to the line or other trouble thereon, thus obviating the delay which ensues if the operator is required to wait until the signaling apparatus has been in operation for a sufiicient length of time to send in a full signal which is otherwise necessary to distinguish such signal from some otheretfect which may be produced on the telephone line, to the end that the central operator may make a direct connection of the telephone line, on which a signal is being transmitted, with the fire department headquarters
  • the invention consists in certain improvements and combinations of parts all as will be hereinafter more fully described, the novel features being pointed out in the claims at the end of the specification.
  • Figure 1 is a diagrammatic view illustrating a telephone exchange system comprising a subscribers instrument circuit, a fire alarm signal box arranged H1- conju'nction therewith, and a fire alarm ap- Specification of Letters Patent.
  • FIGs. 2 and 3 are detail views 'of the signaling apparatus illustrating the preferred form of apparatus for carrying out my invention
  • Fig. 4 is a detail view showing a modis fied arrangement of said device
  • Figs. 5 and 6 are illustrations showing another arrangement of parts by means of which a dis tinctive signal received from an alarm bell may be transmitted.
  • My present invention is applicable to any form or type of calling device or mechanism adapted to'transmit current impulses, or a series of groups of such impulses, and which may be associated with a telephone subscribers instrument circuit for the purpose of indicating an alarm for some particular purpose despatched from the subscribers station.
  • Apparatus embodying my invention is adapted particularly for use in connection with fire alarm signal boxes or mechanism.
  • the essential provide, in conjunction with mechanism of this character, a microphone or some other form of transmitter whichis so arranged in the alarm circuit that a distinctive signal is transmitted thereover simultaneously with the transmission of the impulses of the alarm code.
  • said distinctive signal indicates to the central office operator the operation of the signaling mechanism in addition to the flickering of the visual or pilot light on the central oifice switch-board which flashes in response to the impulses of current transmitted over the telephone circuit by the signaling or calling mechanism.
  • Fig. 1 a simple form: of telephone exchange Bil system, the central office apparatus being that or" the usual central energized type comprising a main battery B to which are,
  • jack springs normally rest in the position shown in dotted lines in Fig. 1 in engagement with the contacts g and h of the pilot lamp circuit, comprising the wires g and h" which receive current from battery B for the purpose of energizing the magnet H which attracts the armature h into engagement with the contact it to close the local circuit of the ilot lamp it, said circuit comprising the wire it attached to the armature k and the wire it leading to the-wire g.
  • wire h lamp it, wires h and g to bat-- tery B.
  • n will b ⁇ understood an during the operation of the fire alarm box' or signaling device assoc1ated with the subscrlbers in-- strument thatthe last described circuit will be energizedeach time the circuit is closed to despatchpan impulseof the. code signal, but as before stated this is recisely, the effect which may beprodhced y the operation of the subscrib'ers receiver hook or from any source of trouble arising on the line.
  • the central oflice switch-board is pro vided with a cord circuit comprising the wires in and ,l terminating in the tip and sleeve" contacts In and Z of a special cord plug from which said wiresleadjto the fire department headquarters er other place Where the alarm recording apparatus may be located.
  • the tire department circuit comprising the wires in and Z as being provided with magnets M which are actuated by circuit impulses received from the bat tery B 'lhese magnets control the armature m of a local circuit supplied with current by the battery 15 and comprising'the magnets 'N of a registering mechanism adapted to perforate a paper tape or ribbon 02, upon each impulse of current transmitted over the local'circuit controlling said registering mechanism, such circuit comprising the wires m, leadmg from the armature m,
  • a calling device comprising a transmitting mecha- I nism embodylng a numeral wheel 1 which is adapted to be rotated in one direction by a suitable gear train comprising a spring 2 and the escapement 3 with which coiiperates the verge 4:, the movement of which may be controlled todetermine the speed ofrotation of the member 1 as by means of a weighted pendulum 5, (Fig. 2).
  • the arbors ofthe various parts of the gear train are journaled in suitable frame pieces, indicated by 6, and the whole is mounted in a suitable casing, comprising a support 7 and a removable cover 8. Carried on the latter is a retainingmember 01' pin 9 which is normally projected in the path of the pendulum 5 against the tension of a spring 10 in which position it is held by theiriable and preferably transparent disk 11 which is held exposed within a flanged collar 12, secured on the exterior or cover of .the casing.
  • This disk is preferably made of glass and may be easily broken to release the, retaining pm 9 to permit'the latter. to bdplojected by the spring to release the pendulum and permit the operation ofthe fire alarm box or signaling mechanism.
  • the member or number wheel 1 is provided with any desired number of teeth, cor-- responding to the code number given the signal box, and coiiperating therewith is a spring 13 which is mounted .on the insulated support l l secured to the framepiece 6.
  • asmall metallic casing 15 containing carbon granules 'or other current modifying medium is closed by diaphragm, 16 to the center of which is secured thelaterally iextending arm 17.
  • the object-oi this spring spring 19 which, may. be adjusted to any its s to provide a tension member which will be vibrated by the jar imparted thereto by the vibration of the alarm mechanism which occurs when the latter is in operation, as will be understood.
  • a signaling device of this character is bridged across the subscribers instrument circuit, as shown in Fig. 1, the bridge circuit being formed by the wires e and f the former leading from the wire 6 to the diaphragm arm 17, and the latter leading from the wire 7 to the contact spring 18. hen the calling device is in its normal position the end of the contact spring 13 lies in,one of the notches of the number wheel or memher 1 so that the bridge or alarm circuit is open at this point.
  • the teeth thereon successively engage the spring 13 and close the bridge and transmit current impulses over the following circuit: battery B, wire 9, contact 9, spring 6, wires 6 and c diaphragm arm 17, thence through the carbon granules or current modifying medium 15, electrode 15, frame 6, wheel 1, contact spring 13, wires 7' and f, spring f, contact h, wires h, magnet H to battery B.
  • the energizin of the magnet H closes the pilot light circuit, as before described, to flash the lamp h and attract the central ofiice operators attention.
  • the latter then inserts the plug of the answering cord A in the subscribers line jack when the tip and sleeve contacts a and a, engage the jack springs, disconnecting the lamp circuit and connecting in the oper-.
  • the fire alarm box or signal transmitting mechanism being then in operation causes an undulatory current to be transmitted over the line during the periods of time the teeth of the number wheel or member 1' are in contact with the spring 13, with the result that the corre sponcling vibration of the diaphragm of the operators receiver d is agitated to give the operator a distinctive signal by which the operation of the fire alarm box may be determined, whereupon the answering cord plug is removed and the plug of the circuit leading to the tire alarm head-quarters is inserted.
  • the last mentioned plug comprising the tip and sleeve contacts and Z, then engage the springs e and f.
  • the circuit thus established may be traced.
  • battery B wire is, contact is, spring 6, wires 6 and c arm 17 carbon 15*, electrode 15, frame 6, wheel 1, spring 13, wires f and f, spring f, contact 1, wire Z, magnets M to battery B rent transmitted over the foregoing circuit, as the teeth of the wheel 1 successively contact with the spring 13, energizes the magnets M and these in turn attractthe armature m of the local circuit of the registering mechanism causing the magnets N of the Each impulse of the curlatter to actuate the device employed for marking or perforating the-record tape or ribbon n in unison with the current impulses transmitted by the number wheel 1 of the impulse transmitter.
  • I have preferably arranged the stationary post 18 at one side of and in rear of the arm 17 so that by adjust-ingthe latter on the diaphragm 16 the tension oi the spring may be increased or diminished so that varying tones may be produced when said sprirn is set in vibration.
  • the form ot the calling deviceillustrated is the same in the princlple of operation as the one hereinbefore described, in that it comprises the clock train, the number wheel 1 and the contact spring. 13*, but in lieu of the transmitter attached to the frame of the calling mechanism -I employ a disk of carbon 25, preferably mounted loosely upon the shaft 26 of the escapement wheel, which will be agitated by the interrupted rotary movement of the latter. lightly against the disk 25 is a leaf spring 27, which forms one of the terminals of the bridge circuit in which the box is arranged.
  • the vibration of the apparatus causes an agitation of the carbon disk 25 on the metallic part of the frame, on which it is supported, causing the central ottlce operator to receive an audible and distinctive signal which may be at once recognized, although not so pleasant and agreeable as the sounds Bearing produced by the vibration of thecoil spring 19, shown in Fig. 2, which may be adjusted to produce various tones.
  • the microphone or transmitter is attached to the post 33 within the bell and is included in the instrument circuit comprising the wires 6 and i
  • This form of the device is particularly adapt ed -for use in connection with fire alarm boxes placed on party telephone lines or those lines to which a plurality of subscribers telephone instruments are connected, as an audible signal of this character can be used to indicate to all of the subscribers, as well as the central operator, the fact that a fire alarm box is in operation so that if said party line is being used by any of the 31 carried on one of the leaves of the fan subscribers, for conversational purposes, such use may be temporarily discontinued until the fire alarm'signal has been transmitted, all of which may, of course, begoverned by proper rules established by the telephone company to Whose lines, the apparatus is applied.
  • a central'telephone othce equipment comprising. a receivcr, of a normally open fire alarm circuitlcading from said oliice a firealarm signal box associated with said circuit comprising movable devices for closing opening said circuit to transmit current Limpulses thereover and embodying a current modifying medium placed .in thecircuit and an ranged to be influenced mechanically bythe movement of said devices during their operation.
  • a normally-open fire alarm circult bridged across the subsc'ribcrs instrument circuit, a fire alarm si al mechanism for alternately closing an opening said bridge and a current modifying medium also arranged. in said bridge and so disposed that it is intluenced by the signal mechanism to vary the resistance of the ire alarm circuit during the transmission of current impulses thereover.

Description

W. L.,'DENIO. FIRE ALARM SYSTEM FOR TELEPHONE EXCHANGES.
. APPLICATION FILED Arms, 1909. E 3, Patented NOV. 14, 1911.
2 SHEETS-SHEET 1.
:5; I anozntm I Mm l v W. L. DBNIO. FIRE ALARM SYSTEM FOR TELEPHONE EXCHANGES.
APPLICATION FILED APR. 5, 1909. 1,608,231 3 v Patented Nov. 14, 1911.
2 SHEETS-SHEET z;
gnucul'oz vm lar n llllll ill Q/vi names UNITE sa- Fran-ALARM SYSTEM son TELEPHONE-EXCHANGES.
To all whom it may concern:
Be it known that I, lVILLIAM L. DENIo, of Rochester, in .the county of Monroe and State of New York, have invented certain new and useful Improvements in F ire-Alarm Systems for Telephone-Exchanges; and I do hereby declare the following to be a full, clear, and exact description of the same, reference being had to the accompanying drawings, forming a part of this specification, and to the reference-numerals marked thereon.
My present invention relates to fire alarm systems which are adapted for use in localities, such as cities, provided with telephone exchange systems and'it has for its primary object the combining with a subscribers telephone circuit, of a fire alarm signaling or calling instrument which when set into operation either automatically or manually will transmit to the exchange operator, in addition to the impulses indicating the number or code signal of the instrument, other impulses which vibrate the diaphragm of the central ofiice operators telephone receiver for the purpose of indicating audibly the operation of the signaling mechanism.
My invention comprehends the arrangement of parts whereby the operation of the signaling apparatus may be immediately recognized by the telephone operator as distinguishing the code signal of the fire alarm apparatus from line disturbances such as an intermittent ground applied to the line or other trouble thereon, thus obviating the delay which ensues if the operator is required to wait until the signaling apparatus has been in operation for a sufiicient length of time to send in a full signal which is otherwise necessary to distinguish such signal from some otheretfect which may be produced on the telephone line, to the end that the central operator may make a direct connection of the telephone line, on which a signal is being transmitted, with the fire department headquarters To these and other ends the invention consists in certain improvements and combinations of parts all as will be hereinafter more fully described, the novel features being pointed out in the claims at the end of the specification.
In the drawings:.Figure 1 is a diagrammatic view illustrating a telephone exchange system comprising a subscribers instrument circuit, a fire alarm signal box arranged H1- conju'nction therewith, and a fire alarm ap- Specification of Letters Patent.
Application filed April 5, 1909.
box in operation, but as a pilot be similarly operated from other disturb- Serial No. 487,980.
paratus actuated thereby all arranged in accordance with my present invention. Figs. 2 and 3 are detail views 'of the signaling apparatus illustrating the preferred form of apparatus for carrying out my invention,
and Fig. 4 is a detail view showing a modis fied arrangement of said device, and Figs. 5 and 6 are illustrations showing another arrangement of parts by means of which a dis tinctive signal received from an alarm bell may be transmitted.
Similar reference numerals in the several figures indicate the same parts.
My present invention is applicable to any form or type of calling device or mechanism adapted to'transmit current impulses, or a series of groups of such impulses, and which may be associated with a telephone subscribers instrument circuit for the purpose of indicating an alarm for some particular purpose despatched from the subscribers station. Apparatus embodying my invention is adapted particularly for use in connection with fire alarm signal boxes or mechanism.
The essential provide, in conjunction with mechanism of this character, a microphone or some other form of transmitter whichis so arranged in the alarm circuit that a distinctive signal is transmitted thereover simultaneously with the transmission of the impulses of the alarm code. In connection with a fire alarm signal box said distinctive signal indicates to the central office operator the operation of the signaling mechanism in addition to the flickering of the visual or pilot light on the central oifice switch-board which flashes in response to the impulses of current transmitted over the telephone circuit by the signaling or calling mechanism. These flashes occurring at regular predetermined intervals will indicate the number of the'fire alarm light may ances on a telephone line, such for instance as the opening and closing o'tthe receiver hook contacts of the telephone set; an intermittent sible for the central oliice operator to distinguish between such causes of trouble and the regularoperation oi the fire alarm box, unless the operator closely observes the flashing of the light, records the same and verifies the number from some record at hand. This all entails delay in transmitting the fire Patented Nov. 14 1911.
ground applied to the line; or an occasional short circuit thereon, it is imposobject of my invention is to alarm signal to the fire head-quarters be cause the operator must wait until at least one full round of the signal box has been transmitted and during this time the operator is also prevented from responding to other cells for connections received over other telephone lines. These diificulties are all eliminated by apparatus'cons'tructed in accordance with my present invention.
In illustrating the operation of devices embodying my invention I have shown in Fig. 1 a simple form: of telephone exchange Bil system, the central office apparatus being that or" the usual central energized type comprising a main battery B to which are,
to the subscribers telephone set comprising the transmitter T and receiver R. The
jack springs normally rest in the position shown in dotted lines in Fig. 1 in engagement with the contacts g and h of the pilot lamp circuit, comprising the wires g and h" which receive current from battery B for the purpose of energizing the magnet H which attracts the armature h into engagement with the contact it to close the local circuit of the ilot lamp it, said circuit comprising the wire it attached to the armature k and the wire it leading to the-wire g.
From the foregoing it will be seen that whenever the telephone instrument circuit is closed current willtraverse the following circuitzfline wire a, spring e, contact g, wire 9, battery B, magnet H, wire h, contact h, spring f to line wire f The energizing of the magnet H attracts it permittingcurrent to flow over the following circuit: battery B, contact h armature 11?,
wire h, lamp it, wires h and g to bat-- tery B.
n will b {understood an during the operation of the fire alarm box' or signaling device assoc1ated with the subscrlbers in-- strument thatthe last described circuit will be energizedeach time the circuit is closed to despatchpan impulseof the. code signal, but as before stated this is recisely, the effect which may beprodhced y the operation of the subscrib'ers receiver hook or from any source of trouble arising on the line. a ,v i
The central oflice switch-board is pro vided with a cord circuit comprising the wires in and ,l terminating in the tip and sleeve" contacts In and Z of a special cord plug from which said wiresleadjto the fire department headquarters er other place Where the alarm recording apparatus may be located. In the present illustration 1 have shown the tire department circuit comprising the wires in and Z as being provided with magnets M which are actuated by circuit impulses received from the bat tery B 'lhese magnets control the armature m of a local circuit supplied with current by the battery 15 and comprising'the magnets 'N of a registering mechanism adapted to perforate a paper tape or ribbon 02, upon each impulse of current transmitted over the local'circuit controlling said registering mechanism, such circuit comprising the wires m, leadmg from the armature m,
and m terminating in the contact m withwhich said armature cotiperates when attracted bythe magnets M -against the ten? sion of the spring m In order to illustrate my invention and give an accurate understanding 0]? its operation I have. shown it applied to a calling device comprising a transmitting mecha- I nism embodylng a numeral wheel 1 which is adapted to be rotated in one direction by a suitable gear train comprising a spring 2 and the escapement 3 with which coiiperates the verge 4:, the movement of which may be controlled todetermine the speed ofrotation of the member 1 as by means of a weighted pendulum 5, (Fig. 2). The arbors ofthe various parts of the gear train are journaled in suitable frame pieces, indicated by 6, and the whole is mounted in a suitable casing, comprising a support 7 and a removable cover 8. Carried on the latter is a retainingmember 01' pin 9 which is normally projected in the path of the pendulum 5 against the tension of a spring 10 in which position it is held by theiriable and preferably transparent disk 11 which is held exposed within a flanged collar 12, secured on the exterior or cover of .the casing. This disk is preferably made of glass and may be easily broken to release the, retaining pm 9 to permit'the latter. to bdplojected by the spring to release the pendulum and permit the operation ofthe fire alarm box or signaling mechanism. r
The member or number wheel 1 is provided with any desired number of teeth, cor-- responding to the code number given the signal box, and coiiperating therewith is a spring 13 which is mounted .on the insulated support l l secured to the framepiece 6.
Also attached. to the latter is asmall metallic casing 15 containing carbon granules 'or other current modifying medium, said case ing being closed by diaphragm, 16 to the center of which is secured thelaterally iextending arm 17.. Extending from the diaphragm arm 17 to the stationary plate or post 18, secured .to the base "2', is a coiled sired tension; The object-oi this spring spring 19 which, may. be adjusted to any its s to provide a tension member which will be vibrated by the jar imparted thereto by the vibration of the alarm mechanism which occurs when the latter is in operation, as will be understood.
A signaling device of this character is bridged across the subscribers instrument circuit, as shown in Fig. 1, the bridge circuit being formed by the wires e and f the former leading from the wire 6 to the diaphragm arm 17, and the latter leading from the wire 7 to the contact spring 18. hen the calling device is in its normal position the end of the contact spring 13 lies in,one of the notches of the number wheel or memher 1 so that the bridge or alarm circuit is open at this point. When the calling device is operated and the member 1 permitted to rotate, the teeth thereon successively engage the spring 13 and close the bridge and transmit current impulses over the following circuit: battery B, wire 9, contact 9, spring 6, wires 6 and c diaphragm arm 17, thence through the carbon granules or current modifying medium 15, electrode 15, frame 6, wheel 1, contact spring 13, wires 7' and f, spring f, contact h, wires h, magnet H to battery B. The energizin of the magnet H closes the pilot light circuit, as before described, to flash the lamp h and attract the central ofiice operators attention. The latter then inserts the plug of the answering cord A in the subscribers line jack when the tip and sleeve contacts a and a, engage the jack springs, disconnecting the lamp circuit and connecting in the oper-.
ators telephone set D. The fire alarm box or signal transmitting mechanism being then in operation causes an undulatory current to be transmitted over the line during the periods of time the teeth of the number wheel or member 1' are in contact with the spring 13, with the result that the corre sponcling vibration of the diaphragm of the operators receiver d is agitated to give the operator a distinctive signal by which the operation of the fire alarm box may be determined, whereupon the answering cord plug is removed and the plug of the circuit leading to the tire alarm head-quarters is inserted. The last mentioned plug, comprising the tip and sleeve contacts and Z, then engage the springs e and f. The circuit thus established may be traced. as follows: battery B wire is, contact is, spring 6, wires 6 and c arm 17 carbon 15*, electrode 15, frame 6, wheel 1, spring 13, wires f and f, spring f, contact 1, wire Z, magnets M to battery B rent transmitted over the foregoing circuit, as the teeth of the wheel 1 successively contact with the spring 13, energizes the magnets M and these in turn attractthe armature m of the local circuit of the registering mechanism causing the magnets N of the Each impulse of the curlatter to actuate the device employed for marking or perforating the-record tape or ribbon n in unison with the current impulses transmitted by the number wheel 1 of the impulse transmitter.
In connecting the spring 19, I have preferably arranged the stationary post 18 at one side of and in rear of the arm 17 so that by adjust-ingthe latter on the diaphragm 16 the tension oi the spring may be increased or diminished so that varying tones may be produced when said sprirn is set in vibration.
In Fig. 4, the form ot the calling deviceillustrated, is the same in the princlple of operation as the one hereinbefore described, in that it comprises the clock train, the number wheel 1 and the contact spring. 13*, but in lieu of the transmitter attached to the frame of the calling mechanism -I employ a disk of carbon 25, preferably mounted loosely upon the shaft 26 of the escapement wheel, which will be agitated by the interrupted rotary movement of the latter. lightly against the disk 25 is a leaf spring 27, which forms one of the terminals of the bridge circuit in which the box is arranged.
When a box of this construction is employed the vibration of the apparatus, causes an agitation of the carbon disk 25 on the metallic part of the frame, on which it is supported, causing the central ottlce operator to receive an audible and distinctive signal which may be at once recognized, although not so pleasant and agreeable as the sounds Bearing produced by the vibration of thecoil spring 19, shown in Fig. 2, which may be adjusted to produce various tones.
As a further example of one of the uses and adaptations of my present invention the arrangement of parts illustrated in Figs.
5 and 6 are shown in which instead of applying the microphone' to the signaling mechanism I have illustrated it as being separated theretrom and adapt-ed to transmit over the telephone circuit the undulatorycurrent produced by the bell '30 which may be sounded in any desired manner during the operation of the alarm mechanism, in the present instance by means .of a tapper 32. In this instance the microphone or transmitter is attached to the post 33 within the bell and is included in the instrument circuit comprising the wires 6 and i This form of the device is particularly adapt ed -for use in connection with fire alarm boxes placed on party telephone lines or those lines to which a plurality of subscribers telephone instruments are connected, as an audible signal of this character can be used to indicate to all of the subscribers, as well as the central operator, the fact that a fire alarm box is in operation so that if said party line is being used by any of the 31 carried on one of the leaves of the fan subscribers, for conversational purposes, such use may be temporarily discontinued until the fire alarm'signal has been transmitted, all of which may, of course, begoverned by proper rules established by the telephone company to Whose lines, the apparatus is applied.
I claim as my invention:
1. The combination with a subscribers telephone instrument circuit and a central office equipment comprising an operators receiver, of mechanism associated with said instrument circuit for transmitting impulses of current thereover by opening and closing said circuit and means for varying the resistance of the circuit during the transmission of the impulses to produce an audible signal in the operators receiver.
2. The combination with a central telephone office equipment comprising an op erators receiver, of a normally opencircuit leading from said central oiiice, mechanism arranged in said circuit for alternately opening and closing it to despatch current impulses comprising" means for varying the resistance in said circuit during the transmission of said impulses. V,
3. The combination With a central'telephone othce equipment comprising. a receivcr, of a normally open fire alarm circuitlcading from said oliice a firealarm signal box associated with said circuit comprising movable devices for closing opening said circuit to transmit current Limpulses thereover and embodying a current modifying medium placed .in thecircuit and an ranged to be influenced mechanically bythe movement of said devices during their operation.
4;. The combination with a subscrihers telephone instrument circuit and a central.
ofiice equipment comprising an operators rece1v er,. ot a normally-open fire alarm circult bridged across the subsc'ribcrs instrument circuit, a fire alarm si al mechanism for alternately closing an opening said bridge and a current modifying medium also arranged. in said bridge and so disposed that it is intluenced by the signal mechanism to vary the resistance of the ire alarm circuit during the transmission of current impulses thereover. k
5. The combination with a central telephone oflice equipment comprising an operators receiver and a normally open fire alarm circuit leading therefrom, of an alarm signal mechanism comprising a gear train, a movable contact member driven thereby and a stationary contact cooperating therewith, a current modifying medium associated with said mechanism and adapted to be agitated by the movement of the gear train, said medium and stationary and movable contacts being disposed in series in the fire alarm circuit for-transmitting current impulses thereover during the operation of the signal mechanism and varying the resistance of said circuit during the transmission of such impulses to produce a distinctive audible signal in the central oilice operators reported on the frame, avcooperating member arranged in juxtapositionv thereto, a current modifying medium located between them and a sound producing device connected to one at the electrodes and adapted to be vibrated lay-movement imparted to it during the operation ofthe signal mechanism.
WILLlA-LM-L. DENEO. Witnesses;
we. 4 v 1 i nosseiiii B t-rnirrrri Lucr A. Van Conan Copies of this patent may be; obtained for five cents each, by addressing the Commissioner: at latentn,
' Washington, I). 6.
devicesg'of an electrode member sup-
US48798009A 1909-04-05 1909-04-05 Fire-alarm system for telephone-exchanges. Expired - Lifetime US1008313A (en)

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