US3466649A - Multiple alarm system - Google Patents

Multiple alarm system Download PDF

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US3466649A
US3466649A US531000A US3466649DA US3466649A US 3466649 A US3466649 A US 3466649A US 531000 A US531000 A US 531000A US 3466649D A US3466649D A US 3466649DA US 3466649 A US3466649 A US 3466649A
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generator
switch
transistor
impedance
tone
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Robert Colman
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General Alarm Corp
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General Alarm Corp
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    • G—PHYSICS
    • G08—SIGNALLING
    • G08B—SIGNALLING OR CALLING SYSTEMS; ORDER TELEGRAPHS; ALARM SYSTEMS
    • G08B3/00—Audible signalling systems; Audible personal calling systems
    • G08B3/10—Audible signalling systems; Audible personal calling systems using electric transmission; using electromagnetic transmission
    • G—PHYSICS
    • G08—SIGNALLING
    • G08B—SIGNALLING OR CALLING SYSTEMS; ORDER TELEGRAPHS; ALARM SYSTEMS
    • G08B13/00—Burglar, theft or intruder alarms
    • G—PHYSICS
    • G08—SIGNALLING
    • G08B—SIGNALLING OR 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

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  • This invention relates to acoustical alarms and more particularly it concerns an electrically operated multiple alarm system.
  • the present invention is particularly useful as a multipurpose alarm arrangement which can be activated by any of several types of disturbance. For example, it is often beneficial to provide an alarm which will sound not only in response to an attempted burglary but which will also sound in response to the pressing of an emergency or doorbell button, and which further will sound in response to the presence of fire or excessive heat.
  • a bell sound could indicate the pressing of a doorbell or emergency button
  • a buzzer or horn sound could indicate the occurrence of a fire
  • a siren sound could indicate the occurrence of an attempted burglary.
  • the present invention overcomes all of these difiiculties. According to the present invention there is provided, in a single package, a novel alarm system which operates to produce various types of alarm sounds including bells, buzzers or horns, and sirens. This novel alarm system requires very little power; and it may be made extremely small, so small in fact, that the entire system, including the power supply, may be mounted as a self contained unit on a door or other closure.
  • the alarm system of the present invention provides different alarm sounds in response to different situations which may take place at a doorway.
  • the system which is completely packaged in a single self contained unit is attached to a door.
  • the unit is interconnected with a doorbell button, a thermostatic heat detector, and a force sensitive switch means. Operation of any of these elements will cause the system to emit a diiferent type of sound at a high volume.
  • the doorbell button when pushed, causes the system to ring in the manner of a doorbell.
  • the thermostatic heat detector on the other hand, when actuated by excessive heat, will cause the system to buzz or sound as a horn.
  • the force sensitive switch means when operated, will cause "the system to emit a siren sound.
  • This siren sound is especially United States Patent 3,466,649 Patented Sept. 9, 1969 effective in calling attention to an attempted breaking into the closure, for it varies in frequency in a particular manner which conveys and maintains a sense of urgency.
  • the present invention achieves the above described results by means of a novel circuit arrangement including a free running or astable tone signal generator having an audible basic frequency. There is additionally provided a free running control generator which is connected to shift the output frequency of the tone signal generator at a subaudible basic frequency. Switch means are arranged in connection with the generators to establish diiferent basic frequency combinations according to the manner in which the switch means are operated. Transducer means, such as a loudspeaker, is connected to convert the output of the tone signal generator to acoustical signals.
  • the tone signal generator comprises an astable multivibrator circuit including a pair of transistors, with cross coupled time delay circuits.
  • the control generator comprises a resistance-capacitance time delay circuit and a voltage responsive breakdown means, such as a unijunction transistor or the equivalent thereof, connected to produce a recurrent sawtooth waveform.
  • Means are provided to couple the time delay circuits of the multivibrator into the control generator so that the time delay action of the timing circuits is varied by the impedance changes which occur during the operation of the control generator.
  • the coupling means additionally includes switching means which introduce different basic impedances between the control generator and the tone signal generator to change the basic frequencies of each of these generators.
  • the switching means serves to change the output of the control generator so that the impedance changes produced by it will follow either a rectangular pulse or a sawtooth Waveform pattern according to the operation of the switching means.
  • the system can be made to produce an assureent siren type sound, a ringing bell sound or a born or buzzer sound.
  • the switching means can be arranged additionally to shift the symmetry, or duty cycle of the astable signal generator so as to simulate more realistically certain tones.
  • FIG. 1 is a fragmentary perspective view illustrating one embodiment of the present invention arranged in conjunction with an entranceway;
  • FIG. 2 is a circuit diagram and schematic mechanical representation of the embodiment of FIG. 1; together with illustrative waveforms shown at selected locations throughout the system; and
  • FIG. 3 is an electrical schematic illustrating a modification of one portion of the circuit of FIG. 2.
  • the entranceway shown in FIG. 1 includes a door which is mounted in the usual manner by means of hinges 12 to one side of a door casing 14.
  • the door 10 is provided with a conventional latch mechanism (not shown) which secures the door in closed position as shown and which is released upon turning a knob 16, so that the door can be opened.
  • a multiple alarm unit 18, forming one embodiment of the present invention, is mounted on the inside surface of the door 10 just above the knob 16.
  • the multiple alarm unit 18, as shown, takes the form of a small rectangular box and is completely self contained except for certain external mechanical connections to be described.
  • a chain lock plate on the casing 14 in close relation to the alarm unit 18.
  • a locking chain 22 may be engaged at one end to the plate 20.
  • the other end of the chain 22 is aifixed to a chain anchor 24 on the multiple alarm unit 18.
  • the plate 20, the chain 22 and the anchor 24 cooperate to provide a chain lock mechanism which, when engaged, permits the door 10 to be opened slightly, but which prevents further opening movement of the door.
  • a door bell button 26 is mounted on the outside surface of the door 10 and is connected mechanically to switching means within the multiple alarm unit 18 in a manner to be described.
  • thermoelectric element 28 which is mounted inside the multiple alarm unit 18.
  • the element 28 is arranged to bend in response to the surrounding temperature exceeding certain prescribed limits, and thus to actuate certain switching means in the system.
  • the multiple alarm unit 18, as will be described becomes actuated in response to either (a) excessive tension on the locking chain 22, (b) pressing of the doorbell button 26, or (c) bending of the bi-metallic thermostatic element 28.
  • Each of these situations will cause the multiple alarm unit 18 to emit a different type of sound. That is, excessive tension on the locking chain 22 will cause the unit 18 to emit a siren sound having a particularly urgent characteristic; the pressing of the doorbell button 26 will cause the unit 18 to emit a ringing bell sound; and the bending of the bi-metallic thermostatic element 28 will cause the unit 18 to emit a horn or buzzer sound.
  • the single unit 18 will respond in difierent ways to different situations, thus enabling a person in the vicinity immediately to assess the particular situation based upon the type of sound he hears without having first to go to the doorway to see what has caused the disturbance.
  • the electrical circuits making up the multiple alarm unit 18 are divided by means of heavy dashed lines A and B into three sep arate sections in which are contained respectively a control generator 30, a tone generator 32, and a power and output circuit 34.
  • Each of the sections is supplied by a common positive voltage supply line 36 and a common negative voltage supply line 38.
  • These supply lines extend through the system from batteries 40 located in the power and output circuit 34.
  • a normally opened main switch 42 is positioned in series with the batteries 40 and serves to connect them with the positive voltage supply line 36. The normally opened switch 42 may be closed in various ways as will be explained more fully hereinafter.
  • the control generator 30 includes a uni-junction transistor 44 having one base terminal connected to the negative voltage supply line 38 and the other base terminal connected via a uni-junction resistor 46 to the positive voltage supply line 36.
  • a sweep generator circuit is also pro vided in the control generator section 30. This sweep generator circuit comprises a sweep resistor 48 and a sweep capacitor 50 connected in series between the positive and negative voltage supply lines 36 and 38.
  • the emitter terminal of the uni-junction terminal transistor 44 is connected to a junction point 52 between the sweep resistor 48 and the sweep capacitor 50.
  • a single-pole-double-throw bell switch 54 is arranged to move between a first position, connected as shown to the junction point 52, and a second position connected to a bell line 56 extending from a junction point 58 between the uni-junction resistor 46 and the uni-junction transistor 44.
  • the output of the bell switch S4 is connected to the movable element of a single-pole-double-throw horn switch 60 which is movable between a first position con nected to a bypass line 62 and a second position connected to one end of a variable impedance resistor 64.
  • the opposite ends of the bypass line 62 and of the variable impedance resistor 64 are each connected to a tone control line 66 which is coupled into the carrier generator 32.
  • the tone generator 32 includes an astable or free running multi-vibrator circuit shown generally at 33.
  • This circuit includes first and second multi-vibrator transistors 68 and 70 of the NPN variety. The emitters of these two transistors are each connected to the negative voltage supply line 38 while their collectors are connected via associated collector resistors 72 and 74 to the positive voltage supply line 36.
  • the multivibrator transistors 68 and 70 are cross coupled between their collectors and bases by means of time delay circuits. These time delay circuits include timing capacitors 76 and 78 connected respectively between the base of one transistor and the collector of the other transistors.
  • the timing circuits each further include a timing resistor 80 and 82 which extends between an associated transistor base terminal and the tone control line 66.
  • the tone control line 66 thus forms a portion of each of the time delay circuits. It will be noted that this line is connected through the control generator 30 to the positive voltage supply line 36. Operation of the control generator 30 serves to vary the impedance between the tone control line 66 and the voltage supply line 36. This in turn affects the operating characteristics of the timing circuits and thereby controls the output frequency of the multivibrator circuit 33.
  • variable duty cycle capacitor 84 and a normally opened duty cycle switch 86 in parallel with the timing capacitor 78.
  • Output signals from the multivibrator circuit 33 are taken from the collector terminal of the second transistor 70, and supplied via a series connected coupling capacitor 88 and a shunt connected output resistor 90 to the base terminal of a power output transistor 92 in the power and output circuit 34.
  • the power output transistor 92 is of the PNP variety and has its emitter terminal connected to the positive voltage and supply line and its collector terminal connected in series with a loudspeaker 94 to the negative voltage supply line 38.
  • the doorbell button 26 is connected to the bell switch 54, the horn switch 60, and the normally opened main switch 42.
  • the bi-metallic thermostatic element 28 in turn, is connected to the horn switch 60, the duty cycle switch 86 and the normally opened main switch 42.
  • the chain anchor 34 on the other hand, is connected only to the normally opened main switch 42.
  • Operation of the above described system is initiated upon closing of the normally opened main switch 42 which effectively places the batteries 40 in circuit across the positive and negative voltage supply lines 36 and 38.
  • the control generator 30 and the tone generator 32 goes into operation at a certain basic frequency and with a certain wave form characteristic, the frequency and wave form characteristic being established by the particular condition of the various switches in these elements at the time the normally opened main switch is closed.
  • the combination of the waveforms and operating frequencies of these two elements will establish the nature of the sound emitted at the loudspeaker 94.
  • the basic operation of the tone generator 32 is the same as that of an ordinary multivibrator. That is, the first and second multi-vibrator transistors 68 and 70 conduct during alternate periods, and the initiation of conduction of either of them causes an immediate extinction of the current flowing through the other thus terminating its conduction. The duration of conduction of each transistor lasts only long enough for a charge to be rebuilt across its respective timing capacitor 76 or 78. When this occurs, the voltage bias at the base terminal of the nonconducting transistor then reaches a level suflicient to bring the transistor into conduction. This in turn causes the voltage level at the base terminal of the other transistor to be immediately reduced below the cut off point of that transistor.
  • This alternate conduction proceeds at a rate established by the capacitance value of the timing capacitors 76 and 78 and amount of impedance which exsists between each transistors base terminal and the positive voltage supply line 36. This, as indicated previously, is varied during operation of the control generator 30.
  • control generator section 30 operates to vary the timing action of the multivibrator 33 is as follows: In order for the timing capacitors 76 and 78 to achieve a sufficient charge to eifect switching of their respective multi-vibrator transistors 68 and 70, it is necessary for current to fiowtinto these capacitors via their respective timing resistors 80 and 82. This current is obtained from the tone control line 66 which ultimately is connected through the control generator 30 to the positive voltage supply line 36. The control generator 30 varies the impedance between the positive voltage supply line 36 and the tone control line 66 and thus varies the rate at which the timing capacitors 76 and 78 achieve their respective charges after each occurrence of transistor switching. Thus, the variations in impedance produced by the control generator serve to control the frequency produced by the tone generator 32.
  • the emitter to base impedance of the unijunction transistor 44 is immediately reestablished and current flowing down through the sweep resistor 48 is again directed into the sweep capacitor 50 so that the capacitor begins to recharge at a relatively slow rate.
  • the voltage at the junction point 52 thus follows a sawtooth pattern, rising relatively gradually to a given threshold level and then dropping abruptly to a lower level.
  • the rate or frequency at which this occurs depends of course upon the respective values of the sweep resistor 48 and the sweep capacitor 50 and also upon the threshold or break down voltage of the unijunction transistor 44.
  • the frequency rate is set to a sub-audible level.
  • the multi-vibrator in cooperation with the low impedance path through the bypass line 62, and the various other system parameters serves to cause the multi-vibrator to oscillate between about 1200 and about 1800 cycles per second.
  • This variation follows a sawtooth pattern, as illustrated by the waveform and takes place at less than 1 cycle per second.
  • the resulting acoustical signal produced at the loudspeaker 94' is a siren sound which varies in such a manner that a special sense of urgency is conveyed.
  • this sense of urgency does not diminish with time, since it is not a type of sound which is easily accommodated by the human ear.
  • OPERATION AS A HORN ALARM Operation of the system as a horn alarm is initiated by the bending of the bi-metallic thermostatic element 28 in response to the ambient temperature exceeding a glven preset value, such as would occur as a result of a fire in the vicinity of the door.
  • a glven preset value such as would occur as a result of a fire in the vicinity of the door.
  • the element 28 bends it causes the normally opened main switch 42 and the duty cycle switch 86 both to close, and it further causes switching of the horn switch 60.
  • the batteries 40 become connected across the positive and negative voltage supply lines 36 and 38 as above described so that the control generator 30 and the tone generator 32 are placed into operation.
  • the switching of the horn switch 60 in the control generator 30 has the effect of placing the variable impedance resistor 64 into circult between the tone control line 66 and the positive voltage supply line 36.
  • the result of this added impedance is that it effectively increases the operating frequency of the control generator 30 and simultaneously decreases the basic operational frequency of the tone generator 32.
  • the parameters or values of the various elements in the control generator section 30 and tone generator 32 are such that the imposition of the variable impedance resistor 64 results in an increase in the control generator frequency to approximately 30 cycles per second and a decrease in the basic operating frequency of the tone generator 32 to between 400 and 600 cycles per second.
  • the resulting signal output causes the loadspeaker 94 to emit a deep throated horn type sound of considerable volume.
  • the quality and authenticity of the horn sound is improved by the closing of the duty cycle switch 86.
  • the impedance variation produced by this connection follows a square wave pattern.
  • the tone generator is shocked into different operating conditions as the impedance on the tone control line 66 is abruptly changed.
  • This sudden shocking of a resonant member, such as the tone generator 32 from one condition to the other, simulates the striking of a bell; and in fact has been found to produce a bell sound at the loudspeaker 94.
  • the quality of the bell sound is improved by the simultaneous operation of the horn switch 60 to place the variable impedance resistor 64 into circuit between the control generator 30 and the tone generator 32.
  • variable impedance resistor 64 and the variable duty cycle capacitor 86 are both shown to be adjustable. Means may be provided to factory set the values of these elements to obtain a particular tonal quality for operation both as a horn and as a bell, or, if desired, any of several well known means may be provided for allowing the user to make his own adjustments in accordance with his individual needs or desires.
  • Unijunction resistor 46 ohms 1.2K Sweep resistor 48 do 3.0K Collector resistors 72, 74 do 1.0K Timing resistors 80, 82 do 12.0K Output resistor 90 do 1.2K Variable impedance resistor 64 (variable) 5.0K Sweep capacitor 50 mfd 100 Timing capacitors 76, 78 pf 47,000 Coupling capacitor 88 mfd l Unijunction transistor 44 2N2646 Multivibrator transistors 68, 70 2N1308 Batteries 40 volts 6 Loudspeaker 94 ohms 8 FIG.
  • FIG. 3 shows a modification of the control generator 30 wherein a PNP type transistor 100, an NPN type transistor 102, and a diode 104 are substituted for the unijunction transistor 44; and an added resistor 106 is connected between the uni-junction resistor 46 and the negative voltage supply line 38.
  • the base of the PNP transistor 100 is connected to a junction between the resistors 46 and 106, and its emitter is connected to the junction point 52 between sweep resistor 48 and the sweep capacitor 50.
  • the junction point voltage causes the base to emitter potential of the PNP transistor 100 to rise above its cut-off point, the transistor begins to conduct and allow current to flow through the diode 104 and a collector connected resistor 108 to the negative voltage supply line 38.
  • the base of the NPN transistor 102 is connected to the emitter of the PNP transistor 100 and thus experiences a voltage increase when the PNP transistor begins to conduct.
  • the collector and emitter of the NPN transistor 102 are connected between the junction point 52 and the negative voltage supply line 38; so that when the base terminal potential is raised above cut-off, the transistor 102 immediately allows the sweep capacitor to discharge.
  • the action thus produced by the two transistor arrangement is thus the same as that produced by the unijunction transistor arrangement of FIG. 2.
  • the two transistor arrangement is more economical in spite of the fact that it requires more elements, since the elements used are more conventional and may be produced at a lower cost.
  • a multiple acoustical alarm system for producing different types of alarm signals according to the occurrence of different conditions, said system comprising a tone signal generator for generating electrical signals which vary at an audible rate, transducer means for converting said electrical signals to corresponding acoustical signals, a control generator for controlling the output frequency of said tone signal generator, said control generator being operable to vary at a basic frequency, and according to a given wave pattern, the output frequency of said tone signal generator, switch means arranged in circuit with said tone signal generator and said control generator to cause said generators to operate at different basic frequencies according to the condition of said switch means, said switch means being arranged to change the basic frequencies of said generators in mutually opposite directions, and means for operating said switch means according to a condition to be repre sented whereby said system produces a different characteristic sound for each condition to be represented.
  • switch means further includes means for switching said control generator in a manner to produce control signals of different Waveshapes.
  • a multiple acoustical alarm system for producing different types of alarm signals according to the occurrence of different conditions comprising, a tone signal generator including an astable multivibrator circuit having cross coupled timing circuits, and having a basic operational frequency within the audible range, a free running control generator having a basic operational frequency below the audible range, said control generator including variable impedance means arranged to be connected into said timing circuits of said tone signal generator for changing the output frequency of said tone signal generator in accordance with the operation of said control generator, a plurality of coupling means having different fixed impedance characteristics, at least one of said coupling means being constructed to simultaneously vary the basic frequencies of said tone signal generator and said control generator, switch means operable to connect dilferent ones of said coupling means between said control generator and said timing circuits according to different conditions to be indicated, whereby the basic operational frequencies of said tone signal generator and said control generator are established by the existence or absence of said conditions, and transducer means for producing acoustical signals in response to output signals from said tone signal generator
  • control signal generator includes a sweep voltage charging circuit and a voltage responsive trigger discharge circuit.
  • said switch means includes means for switching said coupling means alternately between said sweep voltage charging circuit and said trigger discharge circuit.
  • said switch means is operable in response to a first condition to connect a first impedance coupling means between said timing circuits and said sweep voltage charging circuit, and is operable in a second condition to connect a second impedance coupling means, higher than said first impedance coupling means, between said timing circuits and said sweep voltage charging circuit, and is operable in a third condition to connect a third impedance coupling means, higher than said first impedance coupling means, between said timing circuits and said trigger discharge circuits.
  • a multiple acoustical alarm system comprising a tone signal generator including a pair of transistors, a pair of associated time delay circuits cross coupled between said transistors to form an astable multivibrator circuit having a basic output frequency within the audible range, a free running solid-state control generator having a basic operational frequency below the audible range, coupling means interconnecting said control generator and said time delay circuits in a manner such that the basic output frequency of said tone signal generator is modulated with the basic frequency of said control generator, said coupling means including means for switching its basic impedance between discrete values for changing the basic operational frequencies of said multivibrator circuit and said control generator, and loudspeaker means connected to be driven in accordance with output signals from said multivibrator circuit and to generate corresponding acoustical signals.
  • time delay circuits include means for changing the time delay characteristic of one circuit with respect to the other, said last mentioned means being operable by said switch means.
  • time delay circuits include capacitors and resistors connected via a common impedance path to a voltage source, said common impedance path including said coupling means and at least a portion of said control generator.
  • control generator comprises a resistor and a capacitor connected in series between positive and negative voltage supply lines and a threshold voltage responsive capacitor.
  • discharge means connected across said capacitor for effectively discharging same.
  • said discharge means includes resistance means connected between said positive and negative voltage supply lines and a first junction along said resistance means which undergoes a square wave pattern during operation of said control generator while a second junction between said resistor and said capacitor undergoes a sawtooth wave pattern, said switching means further being operative to switch said coupling means alternately between said first and second junctions.
  • a tone signal generator whose basic output frequency varies within the audible range in response to applied control generator outputs, a control generator having an output frequency below the audible range
  • coupling means including a plurality of impedance elements constructed to be connected between the output of said control generator and the input of said tone signal generator, both said tone signal generator and said control generators being constructed to have their basic frequency dependent upon the impedance through said coupling means, said coupling means including switch means operative to produce changes in the impedance value of said coupling means in response to various conditions to be indicated thus to shift the basic frequency of both of said generators, and transducer means connected to the output of said tone signal generator for producing acoustical signals in response to outputs from said tone signal generator.
  • An indicator alarm system for indicating the nature of disturbance to a closure, said system comprising a tone signal generator for generating electrical signals having frequencies within the audio range, said tone signal generator being constructed to produce, in a quiescent state, electrical signals which vary at a basic frequency, transducer means for converting said electrical signals to corresponding acoustical signals, a control generator arranged to shift the output frequency of said tone signal generator, said control generator itself having a subaudible basic frequency, impedance means and plural switch means coupling said tone generator and said control generator in such manner that different combinations of the states of such switch means changes the impedance to cause said generators to operate at different basic frequencies, a plurality of disturbance sensing devices each responsive to a different disturbance at said closure, and means connecting said disturbance sensing devices to said switch means in a manner such that each of said sensing devices responds to a different disturbance by producing a different combination of states of said switch means.
  • control generator is operable to vary a basic frequency of said tone signal generator such that at the occurrence of a first given disturbance, the characteristic sound at said transducer means corresponds to a siren.
  • control generator is operable to vary a basic frequency of said tone signal generator such that at the occurrence of a second given disturbance the characteristic sound at said transducer means corresponds to a bell.
  • An indicator alarm system wherein said control generator is operable to vary a basic frequency of said tone signal generator such that at the occurrence of a third given disturbance the char- OTHER REFERENCES acteristic sound at said transducer means corresponds to Ho: Variable Frequency Square Pulse Gengration, a horn Electronic Engineering, December 1963, pp. 822-823.

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Cited By (7)

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Publication number Priority date Publication date Assignee Title
US3623086A (en) * 1968-11-06 1971-11-23 Schulmerich Mfg Co Solid state control system for striking bells
US3872470A (en) * 1973-04-18 1975-03-18 Airco Inc Audible signal generating apparatus having selectively controlled audible output
US3912952A (en) * 1971-12-27 1975-10-14 Sumitomo Electric Industries Piezoelectric acoustic multiple tone generator
US4078209A (en) * 1977-03-11 1978-03-07 International Telephone And Telegraph Corporation Sound communication system with speaker protection for frequencies below a predetermined minimum
EP0023697A1 (de) * 1979-08-02 1981-02-11 Siemens Aktiengesellschaft Schaltungsanordnung zum Ansteuern eines Signallautsprechers
US10999505B2 (en) * 2016-03-15 2021-05-04 Amazon Technologies, Inc. Low-power-consumption audio/video recording and communication doorbell
IT202200020319A1 (it) * 2022-10-03 2024-04-03 Vimar Spa Dispositivo sonoro per impianti elettrici

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US4151520A (en) * 1977-07-25 1979-04-24 Full Elliott D Portable self-contained alarm with remote triggering capability
GB2151057A (en) * 1983-11-17 1985-07-10 Sakis Roy Alarm device
GB2238412A (en) * 1989-11-21 1991-05-29 Richard Bone Exit signalling device
US5293155A (en) * 1990-05-07 1994-03-08 Wheelock Inc. Interface for a supervised multi-input audible warning system

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US2455472A (en) * 1945-04-10 1948-12-07 Bell Telephone Labor Inc Method and system for electronically generating complex signals
US3114114A (en) * 1960-11-09 1963-12-10 Robert R Atherton Voltage controlled ramp and pulse generator
US3183454A (en) * 1961-04-24 1965-05-11 Autophon Ag Circuit for providing sequences of pulses and intervals
US3196432A (en) * 1960-09-01 1965-07-20 Winston E Kock Transistorized door annunciator utilizing capacitor discharge
US3210686A (en) * 1963-05-03 1965-10-05 Teletype Corp Unijunction oscillator with plural outputs depending on input control

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2455472A (en) * 1945-04-10 1948-12-07 Bell Telephone Labor Inc Method and system for electronically generating complex signals
US3196432A (en) * 1960-09-01 1965-07-20 Winston E Kock Transistorized door annunciator utilizing capacitor discharge
US3114114A (en) * 1960-11-09 1963-12-10 Robert R Atherton Voltage controlled ramp and pulse generator
US3183454A (en) * 1961-04-24 1965-05-11 Autophon Ag Circuit for providing sequences of pulses and intervals
US3210686A (en) * 1963-05-03 1965-10-05 Teletype Corp Unijunction oscillator with plural outputs depending on input control

Cited By (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3623086A (en) * 1968-11-06 1971-11-23 Schulmerich Mfg Co Solid state control system for striking bells
US3912952A (en) * 1971-12-27 1975-10-14 Sumitomo Electric Industries Piezoelectric acoustic multiple tone generator
US3872470A (en) * 1973-04-18 1975-03-18 Airco Inc Audible signal generating apparatus having selectively controlled audible output
US4078209A (en) * 1977-03-11 1978-03-07 International Telephone And Telegraph Corporation Sound communication system with speaker protection for frequencies below a predetermined minimum
EP0023697A1 (de) * 1979-08-02 1981-02-11 Siemens Aktiengesellschaft Schaltungsanordnung zum Ansteuern eines Signallautsprechers
US10999505B2 (en) * 2016-03-15 2021-05-04 Amazon Technologies, Inc. Low-power-consumption audio/video recording and communication doorbell
IT202200020319A1 (it) * 2022-10-03 2024-04-03 Vimar Spa Dispositivo sonoro per impianti elettrici
EP4350653A1 (en) * 2022-10-03 2024-04-10 Vimar S.p.A. Sound device for electrical installations

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FR1512885A (fr) 1968-02-09
BE694799A (forum.php) 1967-08-28
SE340773B (forum.php) 1971-11-29
CH457202A (de) 1968-05-31
GB1180444A (en) 1970-02-04
DE1566699A1 (de) 1970-04-30

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