US504980A - Electrical alarm system - Google Patents
Electrical alarm system Download PDFInfo
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- US504980A US504980A US504980DA US504980A US 504980 A US504980 A US 504980A US 504980D A US504980D A US 504980DA US 504980 A US504980 A US 504980A
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- G—PHYSICS
- G08—SIGNALLING
- G08B—SIGNALLING SYSTEMS, e.g. PERSONAL CALLING SYSTEMS; ORDER TELEGRAPHS; ALARM SYSTEMS
- G08B19/00—Alarms responsive to two or more different undesired or abnormal conditions, e.g. burglary and fire, abnormal temperature and abnormal rate of flow
Definitions
- This invention relates to electric alarms and signals, and is specially design ed to provide a cheap and reliable alarm system for use in factories, stores, private houses, and in such places generally where either fire alarms or burglar alarms or both are desirable, or where signals are to be made.
- the invention also consists in certain novel features forming part of, or capable of being adapted to use in the system as a whole.
- Figure 1 represents a perspective View, parts being broken away, of a central office connected to three houses employing the hereinafter described systern of alarms, the electrical connection in two of the said houses being shown diagrammatically.
- Fig. l represents a diagrammatic view of the circuits shown in Fig.1.
- Fig.2 represents an improved switch which may be used in connection with the leading-in Wires to each house or station.
- Fig. 3 represents a plan view ofthe improved circuit closing device, which may be used with this system for sounding a burglar alarm.
- Fig.4 represents a perspective view of a window fitted with this contact making device to sound a burglar arm.
- Fig. 5 represents a perspective view of a portion of a door fitted with the said contact-making device to sound a burglar alarm.
- Fig.6 represents a side elevation of an improved thermostat adapted to be used with the system.
- the system' consists essentially of an all metallic circuit open at both ends, with the arrangement of signals and alarms hereinafe.
- each of said wires is connected to one terminal of a source of electricity, preferably a battery or 'cell, and included in each of the bridges thus formed is an alarm bell, indicator or other apparatus for signaling.
- the two terminals of a thermostat may also be joined to each of the wires, or the two wires after being insulated with combustible material may be wrapped together thus forming a thermostat, as described in the patent to Kitsee,No. 262,056, granted August 1, 1882. Electrical connection made anywhere between the two wires, will then ring all the alarms whose terminals are connected thereto.
- Fig. 1 In Fig. 1 are shown three housesindicated by H, H and H which are connected to acentral office, by wires 1, 2 and 3, one to each building, and by a general returnwire R connected to all the buildings.
- This return wire B may be supplanted by a return circuit through the earth as indicated in dotted lines at R R and R in which case only one leading in wire toeach house would be required.
- R R and R since each house or group of houses is adapted to make its various signals and alarms independent of the central station, the connections in each house will first be described and then the connections from the house to the central station.
- the wires r r r r and r are in continuous connection, while parallel to these wires and also in continuous conwires in the house H are in no way connected to the central station, and the system in the said house is entirely independent of anything outside of it.
- the battery (3 has one of its terminals connected to the wire 7', and the other terminal is connected by a wire passing through the bell B and switch S 5 hereinafter to be more fully described, to the wire 11.
- thermostats of that class which depend upon heat to close the circuit may be placed.
- Three of these thermostats,indicated by A, A and A are shown in the house H, but any desired number may be used.
- the battery 0 electric bell B, contact piece 8 and switch S are provided. In the same way on the third floor the battery 0 bell B and switch 8, put the two wires in electrical connection.
- the number of batteries, bells and switches on each floor or between the same two groups of wires on several floors, may be varied at.
- the switch S shown in enlarged plan in Fig. 2 is electrically connected to the Wire 11, and may be brought into contact with the contact piece 8 connected to the wire 4", thus cutting out the bell B. Or the, contact piece 8 may be moved so as to also make contact with the switch S
- This contact piece is pivoted at 5 and is provided with a slot 8 in which the clamp screw 8 engages.
- the pivot .9 is electrically connected'by the conducting wire or strip 8 to the binding post 8 which is connected to the wire leading through the bell and through the battery. It will be seen that when the switch S makes connection with both the contact pieces .3 and 8 the circuit will be closed through the bell B as well as through all the other bells B, B &c.
- S is an ordinary push button
- S is a switch normally closing the connection between the bell l3 and the wire 31. If the operator wishes to ring his own bell, as well as all the others on the circuit, he does not touch the switch S but merely presses the push button S when his own bell, and all the other bells in the circuit will ring. But if he wishes to cut out his own bell he should before touching the push button, open the switch S as-indicated in dotted lines.
- any other form of electric signal such as an indicator, might be adopted in place of the bells, or in addition thereto.
- this return wire B may be supplanted by the earth, and that only one wire be led into each house from the central station, and connection be made'with the earth from the houses as at R and R and from the central station as at R
- the leading in wires 1 and r, 3 and 1"", &c. are connected to double switches S and S respectively, at the binding posts .9.
- the arms sof these switches are joined together by an insulating piece 8 havinga hand knob or button 8 and the said arms 8 are adapted to be thrown in and out of contact with the contact strips 3 attached to the wires 11 and r, or 31 and r respectively.
- the switch S is represented as being out of contact with the said contact strips, and therefore the apparatusin the house H is cut ofi from the central station, while the double switch S is represented as making the connection from. the house H to the central station, and therefore the various signals made in the said house would be repeated in the central station.
- the central station is provided with a switch board E of the ordinary type, having binding posts 6 and contact plugs 6 with bells or annunciators, or both, marked to correspond with the house to which it is connected, for instance 1 2 3 8m.
- Each of said bells or annunciators is provided with a battery O 0 or 0 and with a cut out switch S and wires 1 and 37, r and 27,?" and 17 leading to the switchboard as shown. Now suppose the connections be made as inthe house H and a burglar connect the wires r and 31, as by raising the window F.
- the bells in the house H will all ring as hereinbefore described, while the current from the battery (3 will pass through the bell and indicator 3 showing the number of the house and sounding the alarm, down through the switch S and wire 37, to wire 3, and switch S, through wire 31, the burglar alarm contact making device and its connecting wires, back to the wire 0" and double switch S, then through the wire r and return wire R to the switch board, then down to the wire r and back to the opposite pole of the battery C
- a contact made in the building l l will not only sound an alarm throughout that building, but will signatto the central office that something is wrong in the said house.
- the switch S or any other of the switches, or the push button S may be used to make any desired number of short rings.
- the switch S in the central office may be used to make a number of short rings or other prearranged calls in the house H
- the apparatus in each house is capable of being operated in connection with, or entirely independent of the main or central office. It will also be seen that by cutting out each house during the day, any desired calls might be made over that house without signaling to the central station, and that at night by con meeting with the central station the apparatus may be used both as a burglar and fire alarm, and also be used by watchman to notify central that he is awake and on duty.
- This. system is speciallyapplicable to large factories of every description where it is desired to summon foremen and others frequently during the daytime, and to provide alarms against fire and burglars at night.
- the various shops may be connected to the managers office just as the houses H, H and H g
- This form consists of a contact making device .D preferably attached to the frame of the door or window, and a contact breaking device D preferably attached to the door onto the window.
- the part D consists of an insulating block cl having one or more holes (1? for screwing the sameto the woodwork.
- the metal springs d are attached by screws (1 which also clamp the wires 35 and r in contact with the said metal springs d
- a metallic spring plunger (1 passes through a hole in the block and is normally pressed forward by the spring d
- the insulating block D is provided with a wedge 61 and is fastened to the door or window by a screw through the hole d, or in any other convenient way.
- thecut out switch 3 is provided on the inside of the door or window. This should be turned 0d the first thing in the morning, and closed the last thing at night.
- a chronograph may be placed at the central station and connected to each circuit.
- thermostat wherein the circuit is closed by heat
- the form of thermostatshown at K in the lower story of the house H and in detail in Fig. 6, is preferred.
- two metallic pieces 70 connected to the wires 36 and r respectively, are pivoted in an insulating frame k', and are held apart by a fusible strip 75 mounted on the studs 7& of the insulating blocks 7.4 which are secured to the said legs.
- the legs may be allowed to fall together by their own weight after the fusible piece 70 has melted, or they may be drawn together by a spring 70
- the lower ends of the legs It are preferably bent as shown, and.
- the'fusible piece 70 should be made of fusible metal or other substances melting at about 150 Fahrenheit; but when the thermostat is used in cold storage places, a piece of tallow or spermaceti would be a satisfactory substitute for the fusible metal.
- Vhile batteries are referred to throughout the specification, it will be evident that part of the current used in an electric lighting or power system may be used in place of each of the batteries, which current would only flow when the circuit was completed as hereinbefore described. It will thus be seen that the improved system affords a cheap, convenient, and reliable method of making electrical signals on any circuit arranged as herein described, and for sounding fire and burglar alarms.
- a system of electrical fire alarms comprising two continuous conductors insulated from each other, aplurality of sources of electricity having their terminals connected to each of the said continuous conductors, and forming a bridge between the said conductors, an electrically operated signaling device placed in each of the said bridges, and a thermostat for electrically connecting said conductors, and so operating all of said signaling devices,substantially as and for the purposes described.
- a system of electrical alarms comprising two continuous conductors insulated from each other, a plurality of sources of electricity having their terminals connected to each of the said continuous conductors, and forming a bridge between the said conductors, aneleotrically operated signaling device placed in each of the said bridges, a switch adapted to cut out one of said signaling devices and at the same time to electrically connect said continuous conductors, and an adjustable contact piece adapted to engage said switch and so put back into electrical connection said signaling device so cut out, if desired, substantially as and for the purposes described.
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- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Burglar Alarm Systems (AREA)
Description
(No Model.)
. 3 Sheets-Sheet 2. C. K. HALL &7 W. B. LILLARD.
ELECTRICAL ALARM SYSTEM.
' No. 504,980. Patented Sept. 12, 1893.
NEN WQ Q R *1 Wil rw sow 3 Sheets-Sheet 3. C. K. HALL & W. BVLI LARD. ELECTRICAL ALARM SYSTEM.
No. 504,980. 7 Patented se mz; 1893.
UNITED STATES PATENT OFFICE.
CHARLES K. HALL AND WILLIAM .B. LILLARD, OF NEW ORLEANS, LOUISIANA.
ELECTRICAL ALARM SYSTEM.
5'PECIFICATION forming part of Letters Patent No. 504380, dated September 12, 1893.
Application fil d November 2, 1892. Serial No. 450,776. (No model.)
To aZZ whom it may concern.-
Be it known that we, OHARLEs K. HALL and WILLIAM B. LILLARD, citizens of the United States, residing at New Orleans, in the parish of Orleans and State of Louisiana, have invented certain new and useful Improvements in Electrical Alarm Systems; and We do hereby declare the following to be a full, clear, and exact description of the invention, such as will enable others skilled in the art to which it appertains to make and use the same.
This invention relates to electric alarms and signals, and is specially design ed to provide a cheap and reliable alarm system for use in factories, stores, private houses, and in such places generally where either fire alarms or burglar alarms or both are desirable, or where signals are to be made.
The invention also consists in certain novel features forming part of, or capable of being adapted to use in the system as a whole.
Reference is had to the accompanying drawings, wherein the same parts are indicated by the same letters and numerals throughout theseveral views.
Figure 1 represents a perspective View, parts being broken away, of a central office connected to three houses employing the hereinafter described systern of alarms, the electrical connection in two of the said houses being shown diagrammatically. Fig. l represents a diagrammatic view of the circuits shown in Fig.1. 1 Fig.2 represents an improved switch which may be used in connection with the leading-in Wires to each house or station. Fig. 3 represents a plan view ofthe improved circuit closing device, which may be used with this system for sounding a burglar alarm. Fig.4 represents a perspective view of a window fitted with this contact making device to sound a burglar arm. Fig. 5 represents a perspective view of a portion of a door fitted with the said contact-making device to sound a burglar alarm. Fig.6 represents a side elevation of an improved thermostat adapted to be used with the system.
The system'consists essentially of an all metallic circuit open at both ends, with the arrangement of signals and alarms hereinafe.
except that each of said wires is connected to one terminal of a source of electricity, preferably a battery or 'cell, and included in each of the bridges thus formed is an alarm bell, indicator or other apparatus for signaling. The two terminals of a thermostat may also be joined to each of the wires, or the two wires after being insulated with combustible material may be wrapped together thus forming a thermostat, as described in the patent to Kitsee,No. 262,056, granted August 1, 1882. Electrical connection made anywhere between the two wires, will then ring all the alarms whose terminals are connected thereto.
In Fig. 1 are shown three housesindicated by H, H and H which are connected to acentral office, by wires 1, 2 and 3, one to each building, and by a general returnwire R connected to all the buildings. This return wire B may be supplanted by a return circuit through the earth as indicated in dotted lines at R R and R in which case only one leading in wire toeach house would be required. But since each house or group of houses is adapted to make its various signals and alarms independent of the central station, the connections in each house will first be described and then the connections from the house to the central station.
In the house H the wires r r r r and r are in continuous connection, while parallel to these wires and also in continuous conwires in the house H are in no way connected to the central station, and the system in the said house is entirely independent of anything outside of it. The battery (3 has one of its terminals connected to the wire 7', and the other terminal is connected by a wire passing through the bell B and switch S 5 hereinafter to be more fully described, to the wire 11.,
Between the wires of each group, in as many places as may be desired, thermostats of that class which depend upon heat to close the circuit may be placed. Three of these thermostats,indicated by A, A and A are shown in the house H, but any desired number may be used.
Between the wires r and 13, on the second floor of the house H, the battery 0, electric bell B, contact piece 8 and switch S are provided. In the same way on the third floor the battery 0 bell B and switch 8, put the two wires in electrical connection.
The number of batteries, bells and switches on each floor or between the same two groups of wires on several floors, may be varied at.
contact piece .9, switch S ,wire13,thermostat A, wire r and wire 0 thus ringing the bell B, or making such other signal/ as may be placed in the circuit instead of or in addition to the said bell. In the same Way the current from the battery 0 would pass through the bell B switch S ,v wire 14, wire 13, thermostat A, Wire 4' ,wire 1' and back to the battery 0 In the same way the battery 0 would ring its own bell, and all the bells on the circuit would keep ringing as long as the circuit was complete. Now should it be desired to call up a foreman or other person for whom a pre-established signal had been agreed upon, say to the third floor, the person signaling on the third floor would swing the switch S over to the position shown in dotted lines. The bell B would be thrown out of circuit, and will not ring, but the circuit being closed with respect to all the other bells, all the bells on the circuit except the 'bell B will ring, and any desired signal may be made to all parts of the establishment. Should it be desired that the person signaling should ring his own bell, a device like that shown in the lower story of either of the houses 11 or H might be employed.
In the house H the switch S shown in enlarged plan in Fig. 2, is electrically connected to the Wire 11, and may be brought into contact with the contact piece 8 connected to the wire 4", thus cutting out the bell B. Or the, contact piece 8 may be moved so as to also make contact with the switch S This contact piece is pivoted at 5 and is provided with a slot 8 in which the clamp screw 8 engages. The pivot .9 is electrically connected'by the conducting wire or strip 8 to the binding post 8 which is connected to the wire leading through the bell and through the battery. It will be seen that when the switch S makes connection with both the contact pieces .3 and 8 the circuit will be closed through the bell B as well as through all the other bells B, B &c. The same result is accomplished by the device shown on the lower floor of the house H where S is an ordinary push button, and S is a switch normally closing the connection between the bell l3 and the wire 31. If the operator wishes to ring his own bell, as well as all the others on the circuit, he does not touch the switch S but merely presses the push button S when his own bell, and all the other bells in the circuit will ring. But if he wishes to cut out his own bell he should before touching the push button, open the switch S as-indicated in dotted lines.
In the arrangement of the system shown in the house H the bells, batteries and switches form a bridge between the wires 31 and T and thermostats are placed between these two wires as described with reference to the house H. It will be seen by inspection of the figure that if the circuit be closed between the two wires as by the burglar alarm D, all the bells will ring.
While bells have been referred to, any other form of electric signal, such as an indicator, might be adopted in place of the bells, or in addition thereto.
; Having thus described the connection in the two houses, it is purposed to explain how the said houses may be connected to or cutoff from a central station or main office. There is one leading in wire connecting each house with the central station, and indicated by 1, 2, and 3, respectively. Where an all metallic circuit is used there is one return wire R for all the houses with separate leading in wires 7*, T and 7 leading from the main return wire B into each house, and insulated from the wire 1, 2, or 3, as the case may be. It will be evident that this return wire B may be supplanted by the earth, and that only one wire be led into each house from the central station, and connection be made'with the earth from the houses as at R and R and from the central station as at R Assuming, however, that there is an all metallic circuit, the leading in wires 1 and r, 3 and 1"", &c., are connected to double switches S and S respectively, at the binding posts .9. The arms sof these switches are joined together by an insulating piece 8 havinga hand knob or button 8 and the said arms 8 are adapted to be thrown in and out of contact with the contact strips 3 attached to the wires 11 and r, or 31 and r respectively. In Fig. 1 the switch S is represented as being out of contact with the said contact strips, and therefore the apparatusin the house H is cut ofi from the central station, while the double switch S is represented as making the connection from. the house H to the central station, and therefore the various signals made in the said house would be repeated in the central station.
The central station is provided with a switch board E of the ordinary type, having binding posts 6 and contact plugs 6 with bells or annunciators, or both, marked to correspond with the house to which it is connected, for instance 1 2 3 8m. Each of said bells or annunciators is provided with a battery O 0 or 0 and with a cut out switch S and wires 1 and 37, r and 27,?" and 17 leading to the switchboard as shown. Now suppose the connections be made as inthe house H and a burglar connect the wires r and 31, as by raising the window F. The bells in the house H will all ring as hereinbefore described, while the current from the battery (3 will pass through the bell and indicator 3 showing the number of the house and sounding the alarm, down through the switch S and wire 37, to wire 3, and switch S, through wire 31, the burglar alarm contact making device and its connecting wires, back to the wire 0" and double switch S, then through the wire r and return wire R to the switch board, then down to the wire r and back to the opposite pole of the battery C Thus it will be seen that a contact made in the building l l will not only sound an alarm throughout that building, but will signatto the central office that something is wrong in the said house.
Should it be desired to call up the central office from the house H the switch S or any other of the switches, or the push button S may be used to make any desired number of short rings. In the same way the switch S in the central office may be used to make a number of short rings or other prearranged calls in the house H It will be seen that in this system the apparatus in each house is capable of being operated in connection with, or entirely independent of the main or central office. It will also be seen that by cutting out each house during the day, any desired calls might be made over that house without signaling to the central station, and that at night by con meeting with the central station the apparatus may be used both as a burglar and fire alarm, and also be used by watchman to notify central that he is awake and on duty.
By having the apparatus in frequent use for signaling, any defects in the operative parts will be speedily discovered and can be remedied, and this feature renders the system of special advantage over those burglar and tire alarm systems wherein the batteries, wires, &c., remain idle until the emergency occurs, when through disintegration, accident, or other causes they may fail to opcrate.
It will readily be seen that this. system .is speciallyapplicable to large factories of every description where it is desired to summon foremen and others frequently during the daytime, and to provide alarms against fire and burglars at night. In such factories the various shops may be connected to the managers office just as the houses H, H and H g This form consists of a contact making device .D preferably attached to the frame of the door or window, and a contact breaking device D preferably attached to the door onto the window. The part D consists of an insulating block cl having one or more holes (1? for screwing the sameto the woodwork. To the sides of this block the metal springs d are attached by screws (1 which also clamp the wires 35 and r in contact with the said metal springs d A metallic spring plunger (1 passes through a hole in the block and is normally pressed forward by the spring d The insulating block D is provided with a wedge 61 and is fastened to the door or window by a screw through the hole d, or in any other convenient way. When this wedge tongue c1 is pressed between the springs d as in closing the door or shutting the window, the spring plunger (Z is pressed back and the springs (Z are insulated from each other. Now if the door or window be opened, the wedge tongue al will be withdrawn and the spring plunger d will be pressed forward against the spring 61 completing the circuit and sounding an alarm.
Nowto prevent burglar alarms from being sounded, whenever the doors and windows are opened by the proper person, thecut out switch 3 is provided on the inside of the door or window. This should be turned 0d the first thing in the morning, and closed the last thing at night. M
It will be evident that this system of burglar alarms would also furnish information to the main office or other portions of the establishment as to whether the watchman was going his rounds faithfully, and at what time any given shop, house or store was opened or closed.
I As a check on the watchman a chronograph may be placed at the central station and connected to each circuit.
IIO
Any form of thermostat wherein the circuit is closed by heat may be employed, but the form of thermostatshown at K in the lower story of the house H and in detail in Fig. 6, is preferred. In this thermostat two metallic pieces 70 connected to the wires 36 and r respectively, are pivoted in an insulating frame k', and are held apart by a fusible strip 75 mounted on the studs 7& of the insulating blocks 7.4 which are secured to the said legs. The legs may be allowed to fall together by their own weight after the fusible piece 70 has melted, or they may be drawn together by a spring 70 The lower ends of the legs It are preferably bent as shown, and. may be dentatedwhere they are to come together so that scales of rust, grease, &c., that might accumulate on plane surfaces and prevent electrical connection may be pierced or broken by the points of the dentations, and thus good contact be obtained. For ordinary purposes the'fusible piece 70 should be made of fusible metal or other substances melting at about 150 Fahrenheit; but when the thermostat is used in cold storage places, a piece of tallow or spermaceti would be a satisfactory substitute for the fusible metal.
Vhile batteries are referred to throughout the specification, it will be evident that part of the current used in an electric lighting or power system may be used in place of each of the batteries, which current would only flow when the circuit was completed as hereinbefore described. It will thus be seen that the improved system affords a cheap, convenient, and reliable method of making electrical signals on any circuit arranged as herein described, and for sounding fire and burglar alarms.
It will be evident that the system of wiring is exceedingly simple, especially when the return current to the central station is carried to the earth.
It will also be evident that many modifications would readily suggest themselves to any one skilled .in the art, which could be used without departing from the spirit of the invention.
What is claimed as new is 1. A system of electrical fire alarms comprising two continuous conductors insulated from each other, aplurality of sources of electricity having their terminals connected to each of the said continuous conductors, and forming a bridge between the said conductors, an electrically operated signaling device placed in each of the said bridges, and a thermostat for electrically connecting said conductors, and so operating all of said signaling devices,substantially as and for the purposes described.
two continuous conductors insulated from each other, aplurality of sources of electricity having their terminals connected to each of the said continuous conductors, and forming a bridge between the said conductors, an electrically operated signaling device placed in each of the said bridges, and thermostats and contact making devices for sounding burglar alarms placed between the said conduct ors and adapted to make electrical connection between the said conductors, substantially as and for the purposes described.
4. A system of electrical alarms comprising two continuous conductors insulated from each other, a plurality of sources of electricity having their terminals connected to each of the said continuous conductors, and forming a bridge between the said conductors, aneleotrically operated signaling device placed in each of the said bridges, a switch adapted to cut out one of said signaling devices and at the same time to electrically connect said continuous conductors, and an adjustable contact piece adapted to engage said switch and so put back into electrical connection said signaling device so cut out, if desired, substantially as and for the purposes described.
5. In an apparatus of the character described, the combination with two continuous conductors insulated from each other and bridged by wires leading from the terminals of a source of electricity, with electrically operated signals contained in the said bridges, of the switch S forming part of one of said bridges and connected to one of said continuous conductors, the contact piece 5 with which said switch is in contact when said. bridge is closed, the contact piece 5 electrically connected to the other of said continuous conductors and adapted to be in contact with said switch when said bridge is open, and the adjustable contact piece 3 electrically connected to said contact piece .9 and adapted to be thrown into or out of connection with said switch when it is in contact with the contact piece .9 substantially as and for the purposes described.
In testimony whereof we afixoursignatures in presence of two witnesses.
CHARLES K. HALL. WILLIAM B. LILLARD.
Witnesses to signature of O. K. I-Iall:
D. O. MELLEN, LoUI's LION. Witnesses to signature of W. B. Lillard:
GEO. O. KELLER, J OHN BOWEN.
Publications (1)
| Publication Number | Publication Date |
|---|---|
| US504980A true US504980A (en) | 1893-09-12 |
Family
ID=2573815
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| US504980D Expired - Lifetime US504980A (en) | Electrical alarm system |
Country Status (1)
| Country | Link |
|---|---|
| US (1) | US504980A (en) |
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US2446217A (en) * | 1946-06-27 | 1948-08-03 | Herman H Druffel | Burglar alarm |
| US2511955A (en) * | 1948-01-28 | 1950-06-20 | Austin W West | Burglar alarm switch |
| US2537194A (en) * | 1945-11-05 | 1951-01-09 | Edison Inc Thomas A | Phonograph control mechanism |
| US2844675A (en) * | 1956-06-28 | 1958-07-22 | Warner Electric Brake & Clutch | Tension responsive switch |
| US2944252A (en) * | 1957-01-07 | 1960-07-05 | American District Telegraph Co | Intruder alarm system |
-
0
- US US504980D patent/US504980A/en not_active Expired - Lifetime
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US2537194A (en) * | 1945-11-05 | 1951-01-09 | Edison Inc Thomas A | Phonograph control mechanism |
| US2446217A (en) * | 1946-06-27 | 1948-08-03 | Herman H Druffel | Burglar alarm |
| US2511955A (en) * | 1948-01-28 | 1950-06-20 | Austin W West | Burglar alarm switch |
| US2844675A (en) * | 1956-06-28 | 1958-07-22 | Warner Electric Brake & Clutch | Tension responsive switch |
| US2944252A (en) * | 1957-01-07 | 1960-07-05 | American District Telegraph Co | Intruder alarm system |
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