US961146A - Portable telephone and testing instrument. - Google Patents

Portable telephone and testing instrument. Download PDF

Info

Publication number
US961146A
US961146A US54223810A US1910542238A US961146A US 961146 A US961146 A US 961146A US 54223810 A US54223810 A US 54223810A US 1910542238 A US1910542238 A US 1910542238A US 961146 A US961146 A US 961146A
Authority
US
United States
Prior art keywords
conductor
switch
battery
instrument
current
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
US54223810A
Inventor
Nicholas Macking
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
ELMER S WILCOX
Original Assignee
ELMER S WILCOX
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by ELMER S WILCOX filed Critical ELMER S WILCOX
Priority to US54223810A priority Critical patent/US961146A/en
Application granted granted Critical
Publication of US961146A publication Critical patent/US961146A/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

Links

Images

Classifications

    • HELECTRICITY
    • H04ELECTRIC COMMUNICATION TECHNIQUE
    • H04MTELEPHONIC COMMUNICATION
    • H04M1/00Substation equipment, e.g. for use by subscribers
    • H04M1/24Arrangements for testing

Definitions

  • NICHOLAS MACKING OF WILKES-BABRE, PENNSYLVANIA, ASSIGNOR F ONE-HALF TO ELMER S. WILCOX, OF WILKES-BARRE, PENNSYLVANIA.
  • This invention has reference to improvements in telephone and testing instruments and is designed to provide a portable instrument of this character and especially an instrument for telephonic communication which is also adapted for testing the condition of transmission lines or of electrical instruments or both.
  • Figure 1 is a diagram showing the electrical circuits and the several instrumentalities embraced in the instrument as a whole.
  • Figs. 2, 3 and 4 are diagrams illustrating the positions of parts when the instrument 1s used for various purposes.
  • binding posts 2, 3, 4 and 5 respectively.
  • a double blade switch having two blades 6, 7, connected for simultaneous movement by an insulating bar 8 provided with a manipulating knob 9.
  • contacts 10, 11, 12 In the path of the blade 6 are contacts 10, 11, 12 and in the path of the blade 7 is the contact 12 and other contacts 13, 14.
  • the binding post 2 is connected to the blade 6 by a conductor 15 and the binding post 3 is connected to the blade 7 by a,
  • the contacts 10 and 14 are connected together by a conductor 17.
  • the contact 11 is connected by a conductor 18 to a conducting blade 19 provided with a manipulating knob 20.
  • the blade 19 is in normal engagement with the contact terminal 21 connected by a conductor 22 to a magneto 23 and the latter is connected b a conductor 24 to one side of a polarized uzzer 25 the other side of which latter is connected by a Specification of Letters Patent.
  • the conductor 26 connects the contact terminal 13 with one side of a telephone receiver 28 through a binding post 29.
  • the other side of the telephone receiver 28 is connected to a binding post 31 which latter is connected by a conductor to one side of the secondary winding of an induction coil 32, of the usual type employed in the telephone systems.
  • the other side of the secondary winding of the induction coil 32 is connected by a conductor 33 to a contact terminal 34 in the path of, but normally out of contact with the blade 19.
  • Adjacent to the contact terminal 34 is another contact terminal 35 also in the path of the blade 19 when the latter is moved out of engagement with the contact 21 and into engagement with the contact 34, and this last named contact 35 is connected by a conductor 36 including a resistance 35 to the contact 12 ommon to both blades 6 and 7.
  • the contact terminal 34 is connected by a conductor 37 to one side of the primary winding of the induction coil 32 and the other side of this primary winding is connected to a telephone transmitter 38 which in turn is connected by a conductor 39 to the binding post 4.
  • the conductor 39 has branched therefrom a conductor 40 leading to a switch arm 41 to which reference will presently be made.
  • a bridge including a battery 42 and a switch 43 so that the battery 42 may be coupled up between these two conductors or cut out therefrom at will by a suitable manipulation of the switch 43.
  • Branched off from the conductor 36 between the terminal 35 and the bridge connection including the battery 42 and switch 43 is a conductor 44 leading to the binding post 5.
  • Branched ofi from the conductor 40 is another conductor 45 leading to two contact terminals46, 47 in the path of the switch arm 41 in one direction of its movement. Between the point where the conductor 45 connects with the conductor 40 and the switch arm 41, the conductor 40 has included therein an electric lamp 48.
  • Branched between the conductor 36 adja cent to the contact terminal 12 and the conductor 40 between the lamp 48 and the conductor is another conductor 54 including a push button 55 or other like circuit making and breaking device.
  • Fig. 3 the position of the several parts when the instrument is used for telephoning is indicated.
  • Telephone lines 56 are connected to the respective binding posts 2 and 3 and the switch arms 6 and 7 are placed upon the contact terminals 11 and 13 respectively.
  • the crank of the magneto generator 23 is turned and this will cause the polarized buzzer 25 to be actuated and will also cause the actuation of the bells in the telephone system to which the instrumentof the present invention is connected at the binding posts 2 and 3.
  • the switch 43 is now closed and the switch member 19 is moved by a proper manipulation oi the button 20 until the circuit at the contact 21 is broken and the circuit between the contacts 34 and 35 is made by the bridging action of the blade 19.
  • a local circuit is thus established from the battery 42 through the switch 43 to the conductor '36, thence through the contacts 35 and 34 by way of the switch arm 19, thence by the conductor 37 and primary winding of the induction .coil 32, to the transmitter 38 and back again to the battery by way of the conductors 39 and 40.
  • the receiver circuit is established by way of the binding post 2, conductor 15, switch arm 6, contact terminals 11, conductor 18, switch arm 19, circuit terminal 34, conductor 33, secondary winding of the induct-ion coil 32, conductor 30, receiver 28, conductor 27, contact terminal 13, switch arm 7 conductor 16, to the binding post 3.
  • the switch arms 6 and 7 are placed on the contacts 11 and 13 as in Fig. 3 while the line is connected to one of the binding posts 2.or 3 and the other binding post is connected to ground, when upon actuating the magneto 23 the buzzer 25 will respond if a ground be present.
  • Short circuits or grounds of any type of electrical machinery may be tested in like manner.
  • Open circuits will be indicated in like manner with the switch arms 6 and 7 placed as shown in Fig. 3 when, upon completing the circuit at the binding posts 2 and 3 an open circuit of any kind will be indicated by the failure of the buzzer 25 to respond when the magneto 23 is actuated.
  • the battery current is used for testing purposes, such for instance as testing door bells or gas lighters, annunciators or any electrical devices requiring a battery current.
  • the current is reversed by placing the switch arms 6 and 7 on the contact terminals 12 and 14 instead of on the contact terminals 10 and 12.
  • a distant helper may have a battery buzzer connected across the line and then by closing the switch 43 the battery current will be impressed on the line and the buzzer will respond after which the helper may connectup a telephone receiver across the line and then the operator at the testing instrument may place the switch arms 6 and 7 in the position shown in Fig. 3 and conversation ma be carried on in a manner already descrlbed, the helper using the receiver also as a transmitter.
  • the switch arms 6 and 7 are in either the position shown in Fig. 2 or in the position shown in Fig. 4 and let it be assumed that the switch arm 41 is on the contact 49 as shown in Fig. 4 and that the switch 43 is closed.
  • the helper may signal by short circuiting the line when the battery current will flow from the battery 42 through the switch 43 to the conductor 36 thence by way of the terminal 12 and the particular switch arm thereon to line, and, returning through the other switch arm, will flow by way of conductor 51, switch arm 41 through the conductor 40 back to the battery 42 but traversing the lamp 48 and causing the latter to glow thus indicating to the operator at the testing instrument that the helper desires to communicate with him.
  • the switch arm 41 be on the contact 46 then current will flow in substantially the same path except that it will traverse the battery buzzer 52 and pass by the conductor 45 around the lamp 48 back to the battery 42. The lamp will then remain dark and the buzzer will be actuated for signaling purposes. If desirable the telephone circuit may then be coupled up in the manner already described and the operator and helper may communicate in the usual manner. If it be assumed that the testing be necessary in localities where the buzzer would not be audible on account of extraneous noises then the lamp 48 is coupled up in the manner already described and the glowing of the lamp will give indication as to the condition of the line being tested. By shortcircuiting the binding posts 2 and 3 and placing the switch arms 6 and 7 in the position shown in either Figs. 2 and 4 but with the switches 41 and 43 in the position shown in Fig. 4, then the lamp 48 will glow steadily and may be used as a portable lamp.
  • the push button or like device 55 may be manipulated to establish a circuit from the battery 42 by way of the switch 43 and conductor 36 to the con ductor 4O thence by way of the lamp back to the battery 42, this circuit being automatically ruptured on the release of the push button.
  • An electrical testing instrument having a source of direct current, a source of alternating current, a telephone set, means for coupling the source of alternating current or the telephone set to the line at will, signal means responsive to direct current, and means for coupling the telephone set or the signal means to the source of direct current at will.
  • An electrical testing instrument having a telephone set, a source of alternating current, a source of direct current, signal means responsive to alternating current, visual and audible signal means responsive to direct current, means coupling the tele phone set or the signal means to the line to be used or tested, and means for establishing a circuit local to the instrument between the source of direct current and either the visual or audible signal responsive to direct current.
  • An electrical testing instrument having a source of direct current, a telephone set, and a reversing switch for establishing a circuit through the source of current in either direction to the line, or to the telephone set at will.
  • An electrical testing instrument having a source of direct current, visual and audible signal means responsive to such direct current, means for coupling the signal means to line, and means for establishing a local circuit between the source of current and the signal means.
  • a source of direct current, visual and audible signal means local to the instrument, and responsive to direct current, and a reversing switch for coupling the source of current in either direction to the line.
  • An electrical testing instrument having a telephone set, a source of alternating current, a signal means responsive to alternating current, a source of direct current, visual and audible signal means responsive to direct current, means for coupling the visual signal means locally to the sourse of direct current, a reversing switch for coupling the source of direct current in either direct-ion to the line, and means for establishing a circuit between the line and the alternating current source and signal means responsive thereto or to the telephone set at will.

Landscapes

  • Engineering & Computer Science (AREA)
  • Signal Processing (AREA)
  • Investigating Or Analyzing Materials By The Use Of Electric Means (AREA)

Description

I N. MAGKING. PORTABLE TELEPHONE AND TESTING INSTRUMENT.
APPLICATION IILED FEB. 6,1910. I 961,146, Patented June 14,1910.
2 SHEETSSHEET 1.
MDGEW a can! cc. Fummnnuemwneis WASH NGYQI n c N. MAGKING;
PORTABLE TELEPHONE AND TESTING INSTRUMENT.
APPLICATION FILED FEB. 5,1910. 961,146, Patented June 14, 1910.
2 SHEETS-SHEET 2.
illi 5/ 1 Z? Hi5 WM 0 m 52 mww/mfizy UNITED STATES PATENT OFFICE.
NICHOLAS MACKING, OF WILKES-BABRE, PENNSYLVANIA, ASSIGNOR F ONE-HALF TO ELMER S. WILCOX, OF WILKES-BARRE, PENNSYLVANIA.
PORTABLE TELEPHONE AND TESTING INSTRUMENT.
To all whom it may concern:
Be it known that I, N IoHoLAs'MAcKING, a citizen of the United States, residing at- Wilkes-Barre, in the county of Luzerne and State of Pennsylvania, have invented a new and useful Portable Telephone and Testing Instrument, of which the following is a specification.
This invention has reference to improvements in telephone and testing instruments and is designed to provide a portable instrument of this character and especially an instrument for telephonic communication which is also adapted for testing the condition of transmission lines or of electrical instruments or both.
The invention will be best understood from a consideration of the following detail description taken in connection with the accompanying drawings forming a part of this specification, in which drawings,
Figure 1 is a diagram showing the electrical circuits and the several instrumentalities embraced in the instrument as a whole. Figs. 2, 3 and 4 are diagrams illustrating the positions of parts when the instrument 1s used for various purposes.
The several parts of the instrument are inclosed by or supported on a suitable casing which is in part indicated at 1 in Fig. 1 and it will be understood without further illustration that such casing is so constructed as to be readily portable.
In the particular construction shown there are provided four binding posts 2, 3, 4 and 5 respectively. There is also provided a double blade switch having two blades 6, 7, connected for simultaneous movement by an insulating bar 8 provided with a manipulating knob 9. In the path of the blade 6 are contacts 10, 11, 12 and in the path of the blade 7 is the contact 12 and other contacts 13, 14. The binding post 2 is connected to the blade 6 by a conductor 15 and the binding post 3 is connected to the blade 7 by a,
conductor 16. The contacts 10 and 14 are connected together by a conductor 17. The contact 11 is connected by a conductor 18 to a conducting blade 19 provided with a manipulating knob 20. The blade 19 is in normal engagement with the contact terminal 21 connected by a conductor 22 to a magneto 23 and the latter is connected b a conductor 24 to one side of a polarized uzzer 25 the other side of which latter is connected by a Specification of Letters Patent.
Application filed February 5, 1910.
Patented June 14, 1910. Serial No. 542,238.
conductor 26 to a conductor 27 leading to the contact terminal 13. The conductor 27 connects the contact terminal 13 with one side of a telephone receiver 28 through a binding post 29. The other side of the telephone receiver 28 is connected to a binding post 31 which latter is connected by a conductor to one side of the secondary winding of an induction coil 32, of the usual type employed in the telephone systems. The other side of the secondary winding of the induction coil 32 is connected by a conductor 33 to a contact terminal 34 in the path of, but normally out of contact with the blade 19. Adjacent to the contact terminal 34 is another contact terminal 35 also in the path of the blade 19 when the latter is moved out of engagement with the contact 21 and into engagement with the contact 34, and this last named contact 35 is connected by a conductor 36 including a resistance 35 to the contact 12 ommon to both blades 6 and 7.
The contact terminal 34 is connected by a conductor 37 to one side of the primary winding of the induction coil 32 and the other side of this primary winding is connected to a telephone transmitter 38 which in turn is connected by a conductor 39 to the binding post 4. The conductor 39 has branched therefrom a conductor 40 leading to a switch arm 41 to which reference will presently be made. Between the conductors 36 and 40 there is a bridge including a battery 42 and a switch 43 so that the battery 42 may be coupled up between these two conductors or cut out therefrom at will by a suitable manipulation of the switch 43.
Branched off from the conductor 36 between the terminal 35 and the bridge connection including the battery 42 and switch 43 is a conductor 44 leading to the binding post 5. Branched ofi from the conductor 40 is another conductor 45 leading to two contact terminals46, 47 in the path of the switch arm 41 in one direction of its movement. Between the point where the conductor 45 connects with the conductor 40 and the switch arm 41, the conductor 40 has included therein an electric lamp 48.
In the path of the switch arm 41 on the side thereof remote from the contact terminals 46 and 47 are other contact terminals 49 and 50 connected by a conductor 51 to one side of a buzzer 52 responsive to battery current. The other sideof the buzzer '52 is connected by a conductor 53 to the conductor 40 between the lamp 48 and the switch arm 41. The conductor 51 is also continued to the conductor 17.
Branched between the conductor 36 adja cent to the contact terminal 12 and the conductor 40 between the lamp 48 and the conductor is another conductor 54 including a push button 55 or other like circuit making and breaking device.
The several parts of the instrument which must be accessible are exterior to the casing while other parts may be inclosed.
The instrument is susceptible of a great variety of uses and some of these uses are indicated in the drawings.
In Fig. 3 the position of the several parts when the instrument is used for telephoning is indicated. Telephone lines 56 are connected to the respective binding posts 2 and 3 and the switch arms 6 and 7 are placed upon the contact terminals 11 and 13 respectively. The crank of the magneto generator 23 is turned and this will cause the polarized buzzer 25 to be actuated and will also cause the actuation of the bells in the telephone system to which the instrumentof the present invention is connected at the binding posts 2 and 3. The switch 43 is now closed and the switch member 19 is moved by a proper manipulation oi the button 20 until the circuit at the contact 21 is broken and the circuit between the contacts 34 and 35 is made by the bridging action of the blade 19. A local circuit is thus established from the battery 42 through the switch 43 to the conductor '36, thence through the contacts 35 and 34 by way of the switch arm 19, thence by the conductor 37 and primary winding of the induction .coil 32, to the transmitter 38 and back again to the battery by way of the conductors 39 and 40. The receiver circuit is established by way of the binding post 2, conductor 15, switch arm 6, contact terminals 11, conductor 18, switch arm 19, circuit terminal 34, conductor 33, secondary winding of the induct-ion coil 32, conductor 30, receiver 28, conductor 27, contact terminal 13, switch arm 7 conductor 16, to the binding post 3. When it is desired to receive calls, then the switch arms 6 and 7 remain as shown in Fig. 3 and the buzzer 25 will be actuated by an alternating current coming over the line from a dist-ant magneto where a helper may be working and the helper by connecting a receiver across the line may carry on a conversation when the person receiving the call closes the switch 43 and uses the transmitter and receiver in the usual manner.
To use the instrument for testing for grounds on a line the switch arms 6 and 7 are placed on the contacts 11 and 13 as in Fig. 3 while the line is connected to one of the binding posts 2.or 3 and the other binding post is connected to ground, when upon actuating the magneto 23 the buzzer 25 will respond if a ground be present. Short circuits or grounds of any type of electrical machinery may be tested in like manner. Open circuits will be indicated in like manner with the switch arms 6 and 7 placed as shown in Fig. 3 when, upon completing the circuit at the binding posts 2 and 3 an open circuit of any kind will be indicated by the failure of the buzzer 25 to respond when the magneto 23 is actuated.
At times it is desirable to use the cur-rent furnished by the battery 42 for various test purposes or for the production of light. Assuming first that it is desirable to energize an electric lamp for use in some place inaccessible to the testing instrument itself, then the lamp conductors are connected across the binding posts 2 and 3 and the switch arms 6 and 7 "are placed on the contacts 10 and 12 or 12 and 14 when there will be established a circuit from the battery 42, the switch 43 being closed as indicated in Fig. 2, thence to the conductor 36 and by way of the latter to the contact terminal 12 thence through the respective switch arms 6 or 7 and by the latter to the respective conductor 15 or 16 and out through the respective binding post 2 or 3 returning to the other binding post and other switch arm and to the other contact terminal and by way of the conductor 51 through the contact terminals 50 and 47, the switch arm 41 under these conditions bridging these terminals, thence by way of the conductor 45 to the conductor 40 and back to the battery 42. The lamp which may be at the end of long flexible conductors will therefore be lighted and may be used at any desired point. Instead of using the battery current to energize a lamp it maybe used for testing purposes, such for instance as testing door bells or gas lighters, annunciators or any electrical devices requiring a battery current. The current is reversed by placing the switch arms 6 and 7 on the contact terminals 12 and 14 instead of on the contact terminals 10 and 12. A distant helper may have a battery buzzer connected across the line and then by closing the switch 43 the battery current will be impressed on the line and the buzzer will respond after which the helper may connectup a telephone receiver across the line and then the operator at the testing instrument may place the switch arms 6 and 7 in the position shown in Fig. 3 and conversation ma be carried on in a manner already descrlbed, the helper using the receiver also as a transmitter. Let it be supposed that the switch arms 6 and 7 are in either the position shown in Fig. 2 or in the position shown in Fig. 4 and let it be assumed that the switch arm 41 is on the contact 49 as shown in Fig. 4 and that the switch 43 is closed. Now the helper may signal by short circuiting the line when the battery current will flow from the battery 42 through the switch 43 to the conductor 36 thence by way of the terminal 12 and the particular switch arm thereon to line, and, returning through the other switch arm, will flow by way of conductor 51, switch arm 41 through the conductor 40 back to the battery 42 but traversing the lamp 48 and causing the latter to glow thus indicating to the operator at the testing instrument that the helper desires to communicate with him. If the switch arm 41 be on the contact 46 then current will flow in substantially the same path except that it will traverse the battery buzzer 52 and pass by the conductor 45 around the lamp 48 back to the battery 42. The lamp will then remain dark and the buzzer will be actuated for signaling purposes. If desirable the telephone circuit may then be coupled up in the manner already described and the operator and helper may communicate in the usual manner. If it be assumed that the testing be necessary in localities where the buzzer would not be audible on account of extraneous noises then the lamp 48 is coupled up in the manner already described and the glowing of the lamp will give indication as to the condition of the line being tested. By shortcircuiting the binding posts 2 and 3 and placing the switch arms 6 and 7 in the position shown in either Figs. 2 and 4 but with the switches 41 and 43 in the position shown in Fig. 4, then the lamp 48 will glow steadily and may be used as a portable lamp.
It will be observed that whenever the switch 43 is closed there is established a circuit between the binding posts 4 and 5 by way of the conductors 39 and 40 to the battery 42 thence by way of the switch 43 to the conductor 36 and from the latter by the conductor 44 to the binding post 5 so that the battery current may be utilized by connecting suitable conductors to the binding posts 4 and 5 even though the other parts of the instrument be in use between the binding posts 2 and 3. It will be observed that should more battery current be needed than is available in the instrument itself an extra battery may be connected in through the binding posts 4 and 5. It will also be observed that two or more of the portable testing instruments may be coupled up to the line for conversation purposes. It will also be observed that the battery current is readily reversed in direction for purposes where such reversal of the current is needed.
Under some conditions it is desirable to be able to cause the lamp 48 to glow without the necessity of moving the switch 41 and under such circumstances the push button or like device 55 may be manipulated to establish a circuit from the battery 42 by way of the switch 43 and conductor 36 to the con ductor 4O thence by way of the lamp back to the battery 42, this circuit being automatically ruptured on the release of the push button.
What is claimed is 1. An electrical testing instrument having a source of direct current, a source of alternating current, a telephone set, means for coupling the source of alternating current or the telephone set to the line at will, signal means responsive to direct current, and means for coupling the telephone set or the signal means to the source of direct current at will.
2. An electrical testing instrument having a telephone set, a source of alternating current, a source of direct current, signal means responsive to alternating current, visual and audible signal means responsive to direct current, means coupling the tele phone set or the signal means to the line to be used or tested, and means for establishing a circuit local to the instrument between the source of direct current and either the visual or audible signal responsive to direct current.
3. An electrical testing instrument having a source of direct current, a telephone set, and a reversing switch for establishing a circuit through the source of current in either direction to the line, or to the telephone set at will.
4. An electrical testing instrument having a source of direct current, visual and audible signal means responsive to such direct current, means for coupling the signal means to line, and means for establishing a local circuit between the source of current and the signal means.
5. In an electrical testing instrument, a source of direct current, visual and audible signal means local to the instrument, and responsive to direct current, and a reversing switch for coupling the source of current in either direction to the line.
6. An electrical testing instrument having a telephone set, a source of alternating current, a signal means responsive to alternating current, a source of direct current, visual and audible signal means responsive to direct current, means for coupling the visual signal means locally to the sourse of direct current, a reversing switch for coupling the source of direct current in either direct-ion to the line, and means for establishing a circuit between the line and the alternating current source and signal means responsive thereto or to the telephone set at will.
In testimony that I claim the foregoing as my own, I have hereto affixed my signature in the presence of two witnesses.
NICHOLAS MACKING.
WVitnesses:
PAUL J. SCHMIDT, FREDERICK TUSEK.
US54223810A 1910-02-05 1910-02-05 Portable telephone and testing instrument. Expired - Lifetime US961146A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
US54223810A US961146A (en) 1910-02-05 1910-02-05 Portable telephone and testing instrument.

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US54223810A US961146A (en) 1910-02-05 1910-02-05 Portable telephone and testing instrument.

Publications (1)

Publication Number Publication Date
US961146A true US961146A (en) 1910-06-14

Family

ID=3029544

Family Applications (1)

Application Number Title Priority Date Filing Date
US54223810A Expired - Lifetime US961146A (en) 1910-02-05 1910-02-05 Portable telephone and testing instrument.

Country Status (1)

Country Link
US (1) US961146A (en)

Similar Documents

Publication Publication Date Title
US961146A (en) Portable telephone and testing instrument.
US2007669A (en) Meter reading apparatus
US536467A (en) And alexander scott williams
US587433A (en) Mortimer dtt perow
US651326A (en) Electrical hose-signaling apparatus.
US2377162A (en) Portable telephone
US994218A (en) Electric signaling apparatus.
US1007545A (en) Signal system.
US4868847A (en) Telephone intercom device
US271597A (en) Kins automatic
US609173A (en) Telephone system
US536920A (en) Frank r
US1111024A (en) Two-party telephone system.
US1026328A (en) Telephone system.
US982209A (en) Bridging telephone system.
US888748A (en) Signal apparatus for telephone-switchboards.
US1061852A (en) Exchange system for telephone-lines and the like.
US1206053A (en) Telephone fire-alarm apparatus.
US570773A (en) Telephone-switch
US1179175A (en) Telephone system.
US660124A (en) Telephone system.
US653422A (en) Telephone-test set.
US1018666A (en) Telephone system.
US504103A (en) colyin
US539142A (en) Telephone circuit and apparatus