US 3810163 A
Alarm control apparatus for installation in parallel with an actuator switch for an already-installed power supply and annunciator arrangement, which is operable upon occurrence of a predetermined change in environmental conditions, to automatically and repetitively activate the annunciator. Use is made of existing equipment without interference with its normal function. The solid state alarm system permits attachment of a variable number of environmental sensors and is energized only upon activation of one or more of the sensors.
Claims available in
Description (OCR text may contain errors)
United States Patent [1 1 [111 3,810,163 Arnold et al. May 7, 1974 RESIDENTIAL ALARM SYSTEM 3,264,626 8/1966 M66666 340/2131 [7 Inventors: William A' r o dZO Holmes Ave; 3,456,251 7/1969 Smith 340/2l3.l
Roger E. Miller, R.D. No. 1, both of Apalachin, 13732 Primary ExammerThomas B. Habecker 22 Filed: July 26, 1972 I  ABSTRACT  Appl. No.: 275,433
Alarm control apparatus for installation in parallel with an actuator switch for an already-installed power 52 US. Cl 340/310 R, 340/288, 340/227.1 Supply and annunciator arrangement, which is opew [51 Int. Cl. G08) 23/00 ble upon occurrence of a predetermined Change in  new of Search 340/310 227-1 vironmental conditions, to automatically and repetitively activate the annunciator. Useis made of existing  References cued equipment without interference with its normal func- U IT D ST ES ATE S tion. The solid state alarm system permits attachment 2,149,997 3/1939 Hunt 340/227.1 f a variable n mber f nvironmental sensors and is 2,552,331 5/1951 Lamb 340/2271 energized only upon activation of one or more of the 2,954,548 9/1960 Gould n 340/227.1 sensors. 2,982,949 5/l96l Piretz 340/227.l 3,404,393 10/1968 Blivice 340/310 R 3 Claims, 2 Drawing Figures I lob A 4 i ALARM 4 iii 550 [35b SENSOR\ +1,
l l CONTROL UNIT J I l l TIMER i 7 CIRCUIT 1 LJ 16b 1 4 \13/SENS0R 52 L AIENTEDIAY 1 m4 Iii.
35u SENSOR FIG.
RESIDENTIAL ALARM SYSTEM BACKGROUND OF THE INVENTION This invention relates generally to alarm systems and more specifically to residential alarm systems which are connected to and make use of existing equipment.
Alarm systems to detect conditions such as heat, smoke or intrusion are usually independent installations within a building or residence, having their own individual electrical power supply, actuator and alarm. These installations often duplicate other equipment unnecessarily, thus resulting in added expense for both equipment and its installation. In addition, many alarm systems are complicated or dangerous for the homeowner to install because of the need for a relatively high voltage power supply.
Therefore, a primary object of our invention is to provide an alarm system which can be installed readily and inexpensively by a homeowner. This is accomplished by utilizing components and wiring of the annunciator system commonly found in most homes. Such annunciators may be chimes or doorbells. The doorbell or chime provides the audible alarm and is controlled by the invention to cycle on and off when an abnormal environmental condition is sensed. Routine operation of the annunciator system is not impaired.
The alarm system of the invention requires only the low voltages (6 to 35 volts) commonly used for annunciator systems, thus enabling installation by most homeowners. The alarm system is relatively simple to connect with existing equipment or it can be installed during construction. It permits the attachment of a variable number of condition sensors or detectors. Diverse types of remote detectors can also be placed in the circuit,.either during original installation or added at different times.
In the preferred embodiment of our invention, an alarm control means is connected between the low voltage power supply and annunciator device in parallel with the usual switch activator therefor. Remote condition sensors are connected to the control means and power supply. When an abnormal condition is detected by a sensor, the sensor state is changed and the control means becomes energized. The activation initiates cycling of a timer means therein, to provide intermittent energization of the annunciator, either an audible or visual alarm device. The repetitive operation permits the use of chimes, if desired, and produces a continuing alarm to capture attention. This cycling mode also maintains low levels of power consumption with its discontinuous duty cycle.
Sensors are connected to the control means in parallel with each other. Thus the sensors can be located at various places within the building, and sensors responsive to different stimuli can be attached to the same control means.
Other objects of this invention are to provide an alarm system which can be readily tested or deactivated; and to provide an alarm system having a control system that consumes very little power until operational demand occurs.
Various other objects, features and advantages will be apparent from the following detailed description and accompanying drawings to which reference is made and wherein:
FIG. 1 is a schematic diagram of an alarm system constructed according to the principles of the invention; and
FIG. 2 is a schematic diagram of a timing circuit which may be used with the alarm system of FIG. 1.
DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to FIG. 1, an annunciator system commonly installed in a residence is shown. Such a system typically includes a transformer lfl'connected at its primary winding to a I20 volt A.C. supply to provide an output low voltage, usually from 6 to 35 volts. A.C. Connected across the output voltage is an annunciator 11 which can be a bell, chime or buzzer whichis activated by a pushbutton or switch 12, when depressed.
The alarm control system of our invention is connected in parallel with switch 12 and uses power supply 10 for energization and annunciator 11 for the audible alarm. The alarm system comprises generally a control unit 13, shown in phantom, containinga control switch 14, an indicator lamp 15, a timing circuit 16, a test switch 17, and environmental condition sensors 18. Control unit 13, indicated by dot-dash lines, is connected with the annunciator system and sensors at terminal strip 19. Terminals 20 and 21 are connected across the output secondary winding terminals and 10b of the transformer 10, respectively. Terminal 20 of strip 19 is directly connected via wire 26 in the housing to terminal 24, while terminal 21 is connected to the wiper 27 of double pole double throw control switch 14 which has three positions of On, Off and Test". The On and Test positions are commonly connected via wire 29 to timer unit 16 at input terminal 16a to be explained hereinafter. Also connected between wire 26 and input 16a is indicator or pilot lamp 15, which is operable when the alarm system is in use. The output 16c of the timer circuit is connected to the annunciator side of actuator switch 12 via terminal 22 on strip 19.
A second input terminal 16b of the timer circuit is connected to terminal 23 via wire 32. Connected in parallel between power supply wire 26 and wire 32 are a normally open test switch 17 and optional condition sensor 18; Test switch 17 is ganged with wiper 27 on control switch 14 and is closed only when wiper 27 is moved to its Test position. Sensor 18 is normally open and is closed only upon the occurrenceof a predetermined change in the environment, such as reaching a preset level of temperature, smoke concentration or sensing intrusion.
One or more commercially available condition sensors 35a or 35b, etc. are attached in parallel to leads 36 and 37 that are connected to respective terminals 23 and 24 at strip 19. An example of a suitable sensor is a fire detector Model 501 available from Fire Devices Inc., Westport, Connecticut. The actuation of any one sensor is operable to energize the alarm system since it effects a connection of the power on wire 26 to thesec- 0nd input to terminal 16b of the timer circuit.
Timer circuit 16 is used to intermittently energize the annunciator for repetitive, limited periods of time as long as any one sensor is in its activated state of closed contacts. There are several known timer circuits that will operate in this manner; the circuit shown in FIG. 2 is an example. This circuit employs a conventional multivibrator to intermittently gate a triac or bidirectional triode thyristor. In the circuit, diode 38 is collector resistor 43 and 44, are connected in parallel across supply terminals 16b and 16a. The base electrodes of each transistor 41 and 42 are each connected through respective parallel resistors 45 and 46 to a common bias supply established by dropping resistor 47 and Zener diode 48, which are'connected across the input terminals. Each base electrode is also capacitively coupled to the collector of the opposite transistor through capacitors 49 and 50. A triac 51 is connected between input terminal 16a and annunciator side of pushbutton 12. its gate electrode 52 is connected to the collector of transistor 42 through current-limiting resistor 53. A protective circuit of capacitor 54 and resistor 55 reduce large voltage peaks during switching of inductive loads in the annunciator which can cause erratic operation of the triac.
The timer circuit becomes energized only when contacts of one of the normallyopen, parallelconnected sensors 18 or -35, or test switch 17 are closed. When this occurs, transistors 4 l or 42 will alternately conduct so that transistor 42 is switched on and off periodically.- Therefore, triac 51 will be intermittently gated on when its control transistor 42 is switched off, and not gated whentransistor 42 is conducting. The frequency with which transistor 42 conducts is established to a large degree by the values of the base resistors 45 and 46 and capacitors 49 and 50. By appropriately choosing these resistors and capacitors, the timer circuit can provide the desired cycle time for the annunciator.
Another variable in the cycle time is, of course, the supply voltage from the secondary winding of transformer 10. Compensation for different voltages experienced in various annunciator systems is possible by making base resistors 45 and 46 adjustable, since a change in cycle time is directly affected by these resistors. Zener diode 48 establishes desired transistor base voltages and can thus'be selected to provide a compensation for supply voltages from the usual.
In certain cases, a visual annunciator may be desired in addition to or in place of the audible annunciator. Such an indicator lamp 56 may be attached in parallel with annunciator 11, as shown in FIG. 1.
While the invention has been disclosed herein in connection with a particular embodiment and certain structural and procedural details, it will be understood that the foregoing and other changes in form and details may be made therein without departing from the spirit and scope of the invention.
1. In a building having an electrical power supply, an annunciator connected thereto, and a selectively operable actuator for energizing said annunciator across said power supply, alarm control apparatus comprising:
condition sensor means connected to one side of said power supply with said annunciator and operable to change from a non-conducting state to a conducting state upon the occurrence of a predetermined condition;
a gate-controlled semiconductor switch connected between the other side of said power supply and said'annunciator in parallel with said actuator, and a solid state multivibrator connected to said sensor means and said semiconductor switch, said multivibrator being controlled by said sensor means in said conductive state to intermittently cause said semiconductor switch'to be conductive and energize said annunciator.
2. Apparatus as described in claim 1 further including indicator means connected across the power supply for said multivibrator for indicating a ready state of the alarm control means.
3. Apparatus as described in claim 1 wherein said multivibrator comprises a pair of transistors and said gate-controlled semiconductor switch is a bidirectional triode thyristor.