US2728074A - Community alarm system - Google Patents
Community alarm system Download PDFInfo
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- US2728074A US2728074A US271677A US27167752A US2728074A US 2728074 A US2728074 A US 2728074A US 271677 A US271677 A US 271677A US 27167752 A US27167752 A US 27167752A US 2728074 A US2728074 A US 2728074A
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- G—PHYSICS
- G08—SIGNALLING
- G08B—SIGNALLING OR CALLING SYSTEMS; ORDER TELEGRAPHS; ALARM SYSTEMS
- G08B27/00—Alarm systems in which the alarm condition is signalled from a central station to a plurality of substations
- G08B27/006—Alarm systems in which the alarm condition is signalled from a central station to a plurality of substations with transmission via telephone network
Definitions
- An object of this invention is to provide for the reliable transmission of air raid, fire alarm, and no school signals during periods of an emergency.
- Another object of the invention is to provide a device that will furnish 24-hour fire alarm and air raid warning service to local, sparsely settled, communities that cannot aiford to maintain 24-hour police station service, 24- hour fire station service, or 24-hour air raid observation service.
- a feature of the invention is a means wherein a local, sparsely settled community, can make use of the 24-hour police station services available at a larger nearby community for the transmission of air raid alerts, fire alarms, and no school signals.
- the present invention is particularly suitable for use in small sparsely settled communities and villages as it provides a source of 24-hour air raid alert and fire alarm signals for such communities and villages that cannot afiord to maintain a 24-hour air raid observer service, 24- hour police service, or 24-hour fire station service.
- cams RD, F, WH and SCH furnish the timing source for the coded signals representing red alarm, fire alarm, white alarm, and the no school alarm, respectively.
- the series of cams on the left side of the accompanying drawing are driven by the synchronous motor designated MR, While the series of cams on the right side of the drawing are driven by the synchronous motor designated MW.
- the cam designated RD which controls the timing of the red for the siren during each cycle. It should be noticed that the left-hand cams RD and F, are timed on a one-to-one the timing motor MW. As a result, the left-hand cams will be longer than the duty cycle of the right-hand cams.
- relay RDL circuit of relay FL fire alarm that currently may be relay CLR unoperated, to a ground on the microswitch rnicroswitch associated with cam RC will operate soon a after the cams have started to rotate and will thereby close the holding circuit for relay RDL.
- Relay RDL operated prepares a circuit to light lamp RD which indicates the-red alarm is currently 'in progress- Lamp RD will not light until both relays RDL and RD are operated.
- Relay RDL operated, by its second set of contacts, removes a holding circuit for relays FS, WHS and SCS, if operated, and prepares an operating circuit 'for relay RDA.
- the interruption of theoperating paths ofrelays FS, WHS and SCS insures that the fire alarm, white air raid alarm and no school signal could not lie-initiated during the sending of the red air raid alert signal or, ifcurrently being sent, will be discontinued and replaced bythered air raid alarm.
- relay RDL operates motor relay MR over a circuit which consists of the fourth set of contacts on relay RDL, the second set of contacts on relay CLR unoperated, the third set of contacts on relay RDL operated, to a ground on the third set of contacts on relay RDS operated.
- the operation of relay MR closes the energizing circuit for the synchronous motor MR which causes the left-hand set of cams to commence'a clockwise rotation.
- relay RDL prepares a circuit over its fifth. set of contacts for the eventual operation of relay RD.
- cam RC1 causes the operation of its associated microswitch which in turn provides a locking ground for relays. MR and RDL. A short interval of time thereafter cam RC1 allowsthe microswitch associated theerwith to fall into the notch in the cam,'thereby releasing both the microswitch and theRDS relay.
- cam RD causes its associatedmicroswitch to send out a pulsating ground through-the fifth setof-contacts of relay RDL to the winding-of relay RD, thus causing its intermittent operation in accordance with cuttings on cam RD.
- the intermittent operation'of relay RD causes lamp RD to flash and indicate that a red air raidvalarm is in progress. Lamp F will not belit at this time because relay FL remains unoperated during the sending of the red air raid alarm.
- the intermittent operation of relay RD causes its second set of contactsto intermittently short-circuit the two wires connected to them. These two wires are connected to the .telephone line thatleads to the receiving community that is desirous of receiving such alarm signals.
- Appropriatereceiving apparatus in the local community desirous of receiving such alarm signals will respond to the short circuit intermittently placed on the line.
- This receiving apparatus will,-in turn, actuate some alarm disseminating device suchas a siren or whistle so that the local citizens may be promptly informed of the existence of the condition represented by the signal disseminated.
- a test circuit is provided so that the operation of the circuit may be checked Without actually operating the siren or other warning device in the receiving community.
- the lamp associated therewith will flash in accordance with cuttings on the cam representative of the alarm currently in progress, thereby providing the operator with a visual indication of the correct functioning of the entire circuit.
- the microswitch associated with cam RC releases on the' completion of one revolution.
- the release of this microswitch removes the holding ground from relays MR and RDL thereby causing their release.
- the release of relays RDL and MR halts the operation of motor MR A. 1 and restores the entire circuit to normal.
- the circuit is now in condition to initiate the sending of any further signals that may be desired:
- Relay'FL operated also-prepares a circuit so that relay RD will later follow the cuttings on the cam designated F and commence anoperation the frequencyof which-will be determined by the cuttings on cam F.
- relay RD commences an intermittent operation in accordance with the cuttings on camF, it will intermittently short-circuit the telephone line leading to-the receiving community and thereby energize the associated alarm apparatus in that. community.
- Relay RD will also cause lamp F to flash in accordance with the code as determined by earn F.
- relay FL returns to normal in a manner similar to the corresponding relay associatedwiththe red alarm circuit.
- the FS relay releasedas soon as cam RC1 rotated. slightly, thereby releasing its associated micr0switch.. The entire system is again. in a position to.cornmence the initiation of the sending. of anyv furthersignalsthatmay be desired.
- relay RDL If a red alarm key had been operated during the send.- ing of afire alarmsignal, the operation of relay RDL would,; with the aid of .relay RDS, remove the locking circuit for relays FSfand FL, discontinue the sending of a fire alarm, andrestore its circuit to normal. Also, the operation of relays RDS and RDL at this time would initiate the sending of a-red alarm.
- the present invention by means of circuit connections,-eifectively ranks the four signals. in their order of importance to the community.
- the four signals are: red alarm, .fire alarm, white alert and no school...
- the no school alarm is considered to have the .lowest priority; If .any one of the other three alarm keys-is momentarily. operatedwhile a school alarm is in progress-,.the; sending. of the school alarmwill immediatelyrbe discontinued and .the new alarm selected will commence to be emitted.
- the white alarm- is arranged to havezthe next lowest priority. Thus, if: either the red or the fire. alarmvkeys'are operated while a white alarm signal.
- the white alarm willimmediately be discontinued and the new alarm selected will commence to be sent.
- the noschool alarm key is pressedithere will 'be no resultant change in alarm since the ;no*school-alarm hasa lower priority than" the White alarm; The .fireralarm 'is given the second highest priority; The?
- red energization :of the red key will cancel any fire alarmthat'is currently being emitted and substitute therefortheHredalarm in its place.-
- the red alarm is considered to have the highest priority and therefore the operation of a any one of the other-three alarm keys'while a red alarm'is being sentwill'have no elfect onthe circuit.”
- The-'only-waya red alarm can be canceled is by the'operation of the cancel key.
- Relay RDA is so connected that it will follow the operations of relay RD only when relay RDL is also operated. Relay RDA will not follow the operations of relay RD if relay FL is operated. Similarly, relay WHA is so connected that it will only respond to the intermittent operations of relay WH when relay WHL is operated. Relay Wl-IS will not respond to the operations of relay WH during the sending of the no school alarm.
- a signaling system adapted to impress a plurality of differently coded electrical signals upon an output circuit such as a communication line, a plurality of selection means, a plurality of switching means each of which is operable by a related one of said selection means, a plurality of timing means each of which is operable by a related one of said switching means, a plurality of signaling means each of which is adapted to be connected by said switching means on a mutually exclusive basis to different ones of said timing means, means operable by operable in response to the operation of said signaling means to impress upon said output circuit a distinctive coded signal as determined by said timing means.
- a signaling system adapted to impress a plurality of differently coded electrical signals upon an output circuit such as a communication line, a plurality of selection means, a plurality of switching means each of which is operable by a related one of said selection means, a plurality of timing means each of which is operable by a related one of said switching means, a plurality of signaling means each of which is adapted to be connected by press its own distinctive coded signal on said output circuit.
- a plurality of selection means adapted to impress a plurality of differently coded electrical signals upon an out- 6 put circuit such as a communication line
- a plurality of switching means each of which is operable by a related one of said selection means
- a plurality of timing means each of which is operable by a related one of said switching means
- a plurality of signaling means each of which is adapted to be connected by said switching means to different ones of said timing means, means operable by each of said switching means when energized to cause its related timing means to operate the signaling means currently associated.
- each selection means of a higher priority may be effective to cancel the operation of the timing means associated with selection and switching distinctive coded signal on said output circuit, and means to cancel the operation of any signaling means and to halt the sending of any coded signal over said output circuit.
- means including relay contacts operable by each of said switching relays when energized whereby the cam contacts associated with the with said related timing cam, impressers of electrical variations operable whereby the operation of said signal- 7 ing relay impresses upon said; output circuita distinctive codedsignalas determined by said timing-cam.
- a plurality of timing means a plurality-of signaling means each of which is associated on a, mutually exclusive basis to different ones of said.
- timing means a plurality of selection means with each being functionally related to an individual one of said timing means, a plurality of switching means each operable by a related one of said selection means, means op-.
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Description
Dec. 20, 1955 o. CESAREO COMMUNITY ALARM SYSTEM Filed Feb. 15, 1952 IIYVVENTOR 0. CESAREO 'Orfeo Cesareo, Washington Township,
United States Patent 0 2,728,074 COMMUNITY ALARM SYSTEM Bergen County, N. 1., assignor to Bell Telephone Laboratories, Incorporated, New York, N. Y., a corporation of New York Application February 15, 1952, Serial No. 271,677 8 Claims. (Cl. 340-346) This invention relates to a signaling system and more particularly to a system for disseminating air raid, fire alarm, and no school signals to a community.
An object of this invention is to provide for the reliable transmission of air raid, fire alarm, and no school signals during periods of an emergency.
Another object of the invention is to provide a device that will furnish 24-hour fire alarm and air raid warning service to local, sparsely settled, communities that cannot aiford to maintain 24-hour police station service, 24- hour fire station service, or 24-hour air raid observation service.
A feature of the invention is a means wherein a local, sparsely settled community, can make use of the 24-hour police station services available at a larger nearby community for the transmission of air raid alerts, fire alarms, and no school signals.
The accompanying drawing illustrates a complete circuit of a preferred exemplary embodiment of the invention.
The present invention is particularly suitable for use in small sparsely settled communities and villages as it provides a source of 24-hour air raid alert and fire alarm signals for such communities and villages that cannot afiord to maintain a 24-hour air raid observer service, 24- hour police service, or 24-hour fire station service.
alarm, a White air raid alarm, a no school signal, and a fire alarm signal.
The operator that controls this system would receive the signal to commence operation from some external The notice to the operator to commence sounding an air raid alarm would probably be received from a small community desirous of receiving such signals. A siren located in the village desirous of receiving the alarm pending on the type of warning apparatus utilized. A series of cams driven by synchronous motors furnish the timing source for the coded signals. Each cam is cut to a different pattern and each is chosen to represent a desired signal. As shown on the accompanying drawing, cams RD, F, WH and SCH, furnish the timing source for the coded signals representing red alarm, fire alarm, white alarm, and the no school alarm, respectively. The series of cams on the left side of the accompanying drawing are driven by the synchronous motor designated MR, While the series of cams on the right side of the drawing are driven by the synchronous motor designated MW. The cam designated RD, which controls the timing of the red for the siren during each cycle. It should be noticed that the left-hand cams RD and F, are timed on a one-to-one the timing motor MW. As a result, the left-hand cams will be longer than the duty cycle of the right-hand cams. Cams RC, RC1, WC
switches cooperating The entire system is controlled by means of five keys wh1ch are designated RD, F, WH, SC and The operation tarily operating sired to be sent.
will move in a clockwise direction as shown in the drawmg, and therefore, the microswitch associated with cam currently in progress in a manner hereinafter.
The operation of relay RDL circuit of relay FL fire alarm that currently may be relay CLR unoperated, to a ground on the microswitch rnicroswitch associated with cam RC will operate soon a after the cams have started to rotate and will thereby close the holding circuit for relay RDL. Shortly thereafter-the'microswitchassociated with cam RC1 releases and-thereby releases relay RDS byopening'its-holdi'ng path; Relay RDL operated, prepares a circuit to light lamp RD which indicates the-red alarm is currently 'in progress- Lamp RD will not light until both relays RDL and RD are operated.
Relay RDL operated, by its second set of contacts, removes a holding circuit for relays FS, WHS and SCS, if operated, and prepares an operating circuit 'for relay RDA. The interruption of theoperating paths ofrelays FS, WHS and SCS insures that the fire alarm, white air raid alarm and no school signal could not lie-initiated during the sending of the red air raid alert signal or, ifcurrently being sent, will be discontinued and replaced bythered air raid alarm.
' The operation of relay RDL operates motor relay MR over a circuit which consists of the fourth set of contacts on relay RDL, the second set of contacts on relay CLR unoperated, the third set of contacts on relay RDL operated, to a ground on the third set of contacts on relay RDS operated. The operation of relay MR closes the energizing circuit for the synchronous motor MR which causes the left-hand set of cams to commence'a clockwise rotation.
The operation of relay RDL prepares a circuit over its fifth. set of contacts for the eventual operation of relay RD.
As soonas relay MR is energized, the synchronous motor MR commences operation and rotates the lefthand cams clockwise. The instant the left-hand set of cams commence its clockwise rotation, cam RC causes the operation of its associated microswitch which in turn provides a locking ground for relays. MR and RDL. A short interval of time thereafter cam RC1 allowsthe microswitch associated theerwith to fall into the notch in the cam,'thereby releasing both the microswitch and theRDS relay.
The rotation of cam RD causes its associatedmicroswitch to send out a pulsating ground through-the fifth setof-contacts of relay RDL to the winding-of relay RD, thus causing its intermittent operation in accordance with cuttings on cam RD. The intermittent operation'of relay RD.causes lamp RD to flash and indicate that a red air raidvalarm is in progress. Lamp F will not belit at this time because relay FL remains unoperated during the sending of the red air raid alarm. The intermittent operation of relay RD causes its second set of contactsto intermittently short-circuit the two wires connected to them. These two wires are connected to the .telephone line thatleads to the receiving community that is desirous of receiving such alarm signals. Appropriatereceiving apparatus in the local community desirous of receiving such alarm signals will respond to the short circuit intermittently placed on the line. This receiving apparatus will,-in turn, actuate some alarm disseminating device suchas a siren or whistle so that the local citizens may be promptly informed of the existence of the condition represented by the signal disseminated.
A test circuit is provided so that the operation of the circuit may be checked Without actually operating the siren or other warning device in the receiving community. As the check key is operated, the lamp associated therewith will flash in accordance with cuttings on the cam representative of the alarm currently in progress, thereby providing the operator with a visual indication of the correct functioning of the entire circuit.
The microswitch associated with cam RC releases on the' completion of one revolution. The release of this microswitch removes the holding ground from relays MR and RDL thereby causing their release. The release of relays RDL and MR halts the operation of motor MR A. 1 and restores the entire circuit to normal. The circuit is now in condition to initiate the sending of any further signals that may be desired:
The operation of this system to initiate a fire alarm follows the same general principles as did the circuit for the red air raid alarm. The operation of the F key will cause the operation of the FS relay which, in turn, will cause the operation of the CLW relay which will cancel the sending of any white alarm or no school alarm currently in progress by opening the holding paths for the relays associated with the circuits controlled by said alarms. The operation of relay. FS also causes operation of relay FL which, in turn, locks over the third set of contacts-on relay RDL to'a ground on cam RC. This ground will not be in effect until the cams have rotated a slight amount. Relay FL operated, closes the circuit for the operation of relay MR which starts the synchronous motor MR in a similar fashion as hereinbefore described. I
Relay'FL operated, also-prepares a circuit so that relay RD will later follow the cuttings on the cam designated F and commence anoperation the frequencyof which-will be determined by the cuttings on cam F. As relay RD commences an intermittent operation in accordance with the cuttings on camF, it will intermittently short-circuit the telephone line leading to-the receiving community and thereby energize the associated alarm apparatus in that. community.
Relay RD will also cause lamp F to flash in accordance with the code as determined by earn F. At the end of one revolution of camsRC and RC1, relay FL returns to normal in a manner similar to the corresponding relay associatedwiththe red alarm circuit. The FS relay releasedas soon as cam RC1 rotated. slightly, thereby releasing its associated micr0switch.. The entire system is again. in a position to.cornmence the initiation of the sending. of anyv furthersignalsthatmay be desired.
If a red alarm key had been operated during the send.- ing of afire alarmsignal, the operation of relay RDL would,; with the aid of .relay RDS, remove the locking circuit for relays FSfand FL, discontinue the sending of a fire alarm, andrestore its circuit to normal.. Also, the operation of relays RDS and RDL at this time would initiate the sending of a-red alarm.
The present invention, by means of circuit connections,-eifectively ranks the four signals. in their order of importance to the community. In. the order.of :their importance,; and in order of left to right as shown on the drawing, the four signals are: red alarm, .fire alarm, white alert and no school... The no school alarm is considered to have the .lowest priority; If .any one of the other three alarm keys-is momentarily. operatedwhile a school alarm is in progress-,.the; sending. of the school alarmwill immediatelyrbe discontinued and .the new alarm selected will commence to be emitted. The white alarm-is arranged to havezthe next lowest priority. Thus, if: either the red or the fire. alarmvkeys'are operated while a white alarm signal. is being sent, the white alarm willimmediately be discontinued and the new alarm selected will commence to be sent. As might be. expected, if while the white..alarm:is beingxemitted, the noschool alarm key is pressedithere will 'be no resultant change in alarm since the ;no*school-alarm hasa lower priority than" the White alarm; The .fireralarm 'is given the second highest priority; The? energization :of the red key will cancel any fire alarmthat'is currently being emitted and substitute therefortheHredalarm in its place.- The operation of the whiteor schoolkey while the the alarm is being emitted; would have no-eifect..- The red alarm is considered to have the highest priority and therefore the operation of a any one of the other-three alarm keys'while a red alarm'is being sentwill'have no elfect onthe circuit." The-'only-waya red alarm can be canceled is by the'operation of the cancel key.
Theoperation of the rightset of cams, and theiequipalarm to additional communities that do not desire reception of the fire alarm or no school alarm signals. Relay RDA is so connected that it will follow the operations of relay RD only when relay RDL is also operated. Relay RDA will not follow the operations of relay RD if relay FL is operated. Similarly, relay WHA is so connected that it will only respond to the intermittent operations of relay WH when relay WHL is operated. Relay Wl-IS will not respond to the operations of relay WH during the sending of the no school alarm.
The operation of the cancel key will operate relay (LR and in turn relay CLW which together will halt the sending of any alarm currently in progress by opening the holding circuit for the relays associated with said alarm.
It is to be understood that the above-described arrangements are but illustrative of the application of the principles of the invention. Numerous other arrangements may be devised by those skilled in the art without departing from the spirit and scope of the invention.
What is claimed is:
1. In a signaling system adapted to impress a plurality of differently coded electrical signals upon an output circuit such as a communication line, a plurality of selection means, a plurality of switching means each of which is operable by a related one of said selection means, a plurality of timing means each of which is operable by a related one of said switching means, a plurality of signaling means each of which is adapted to be connected by said switching means on a mutually exclusive basis to different ones of said timing means, means operable by operable in response to the operation of said signaling means to impress upon said output circuit a distinctive coded signal as determined by said timing means.
2. In a signaling system adapted to impress a plurality of differently coded electrical signals upon an output circuit such as a communication line, a plurality of selection means, a plurality of switching means each of which is operable by a related one of said selection means, a plurality of timing means each of which is operable by a related one of said switching means, a plurality of signaling means each of which is adapted to be connected by press its own distinctive coded signal on said output circuit.
3. In a signaling system adapted to impress a plurality of differently coded electrical signals upon an out- 6 put circuit such as a communication line, a plurality of selection means, a plurality of switching means each of which is operable by a related one of said selection means, a plurality of timing means each of which is operable by a related one of said switching means, a plurality of signaling means each of which is adapted to be connected by said switching means to different ones of said timing means, means operable by each of said switching means when energized to cause its related timing means to operate the signaling means currently associated.
so that the operation of each selection means of a higher priority may be effective to cancel the operation of the timing means associated with selection and switching distinctive coded signal on said output circuit, and means to cancel the operation of any signaling means and to halt the sending of any coded signal over said output circuit.
4. In a signaling system adapted to impress a plurality of diiierently coded electrical signals upon a first and a second output circuit, a plurality of selection means, a
5. In a signaling system adapted to impress a plurality of difierently coded electrical signals upon an output cirones of said timing cam contacts, means including relay contacts operable by each of said switching relays when energized whereby the cam contacts associated with the with said related timing cam, impressers of electrical variations operable whereby the operation of said signal- 7 ing relay impresses upon said; output circuita distinctive codedsignalas determined by said timing-cam.
6', In a signaling system adapted to impress a plurality of differently coded electrical signals upon a first anda second output circuit, four selection switches, four switching relays each of which is operable by a related one of said-selection switches, four peripherically notched timing cams each of whose operation is initiated by the operation of a related one of said switching relays,a pair of contacts associated with each cam and operable by the periph:
eral notches thereon, two signaling relays each of which erable whereby the operation of said signaling relay impresses upon said first output circuit a distinctive coded signal as determined by the peripheral notches in said timing cam, means whereby all of said selection switches and switching relays are connected in a circuit that determines the relative priority of each coded signal and its related timing cam and switching relay so that the operation of any selection switch of a higher priority may be effective to cancel the operation of the timing cams associated with selection switches and switching relays of a lower priority and to initiate the operation of its related timing cam and thereby impress its own distinctive coded signal on said first output circuit, two additionalsignaling relays whereby only certain predesignated ones of said timing cams may impress their own distinctive coded signals upon said second output circuit, additional switching means to cancel the operation of all signaling relays and to halt the sending of any coded signal over said output circuits.
7. In a signaling system, a plurality of timing means, a
plurality'of signalingameans each ofwhich is associated on amutually, exclusive'basis to different ones of said timing means, ;a plurality of selection means with each being functionally related to an individual one of said timing-means, apluralit'yof switching means each operable by a related one of said selection means, means operable by said switching means to causea related one of said timing means to operate the signaling means currently associated-with the individual said-timing means, and means whereby all but one of said selection means may he eiiective to cancel the operation of signaling means associated with some :of the other selection means and to initiate the operation of its related signaling means. 1
8. In a signaling system, a plurality of timing means, a plurality-of signaling means each of which is associated on a, mutually exclusive basis to different ones of said.
timing means, a plurality of selection means with each being functionally related to an individual one of said timing means, a plurality of switching means each operable by a related one of said selection means, means op-.
erable by said switching means to'lcause a related one or said timing means to operate-the signaling means currently associated with the individual said tim'mg means,
means wherebyall butlone of said selection means may be effective to cancel the operation of signaling means associated, with some of the other selection means and to initiate the operation of its related signaling means, and means effective to cancel the operation of all signaling means.
References Cited in the file of this patent UNITED STATES PATENTS
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
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US271677A US2728074A (en) | 1952-02-15 | 1952-02-15 | Community alarm system |
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
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US271677A US2728074A (en) | 1952-02-15 | 1952-02-15 | Community alarm system |
Publications (1)
Publication Number | Publication Date |
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US2728074A true US2728074A (en) | 1955-12-20 |
Family
ID=23036592
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
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US271677A Expired - Lifetime US2728074A (en) | 1952-02-15 | 1952-02-15 | Community alarm system |
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US (1) | US2728074A (en) |
Cited By (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US3124749A (en) * | 1964-03-10 | Conelrad-broadcast station control device | ||
US3441929A (en) * | 1965-12-30 | 1969-04-29 | Ref Con Corp | Remote reporting system |
US3883866A (en) * | 1973-08-14 | 1975-05-13 | John K Kneeland | Alarm generator |
Citations (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US1175405A (en) * | 1913-09-06 | 1916-03-14 | Grove P Mitchell Jr | Automatic signal device. |
US1749444A (en) * | 1926-07-20 | 1930-03-04 | Frank B Rae | Signal system |
US2183245A (en) * | 1934-07-13 | 1939-12-12 | American District Telegraph Co | Alternating current operated noninterfering signaling system |
US2204420A (en) * | 1939-07-11 | 1940-06-11 | Signaphone Corp | Alarm system |
US2390449A (en) * | 1942-06-29 | 1945-12-04 | Arvid N Montgomery | Alarm system |
-
1952
- 1952-02-15 US US271677A patent/US2728074A/en not_active Expired - Lifetime
Patent Citations (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US1175405A (en) * | 1913-09-06 | 1916-03-14 | Grove P Mitchell Jr | Automatic signal device. |
US1749444A (en) * | 1926-07-20 | 1930-03-04 | Frank B Rae | Signal system |
US2183245A (en) * | 1934-07-13 | 1939-12-12 | American District Telegraph Co | Alternating current operated noninterfering signaling system |
US2204420A (en) * | 1939-07-11 | 1940-06-11 | Signaphone Corp | Alarm system |
US2390449A (en) * | 1942-06-29 | 1945-12-04 | Arvid N Montgomery | Alarm system |
Cited By (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US3124749A (en) * | 1964-03-10 | Conelrad-broadcast station control device | ||
US3441929A (en) * | 1965-12-30 | 1969-04-29 | Ref Con Corp | Remote reporting system |
US3883866A (en) * | 1973-08-14 | 1975-05-13 | John K Kneeland | Alarm generator |
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