US 3283316 A
Description (OCR text may contain errors)
Nov. 1, 1966 D. E. BEARDMORE ETAL 3,283,316
POWER LINE SIGNAL SYSTEM HAVING A RELAY CONTROLLED INDICATOR AT THE RECEIVER Filed 001'.- 31, 1962 I 58 g a 24 2 TRANSM/T/Z'R 96 M0102 6,4 RECf/l/E/f 52 [Li [L4 1 4,9- 2.
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United States Patent necticut Filed Oct. 31, 1962, Ser. No. 234,368 2 Claims. (Cl. 340-310) This invention relates to control and alarm apparatus. More specifically the invention relates to fire alarm systems for use in residential applications.
Fire alarm systems known to the prior art customarily consist of highly specialized devices which are custom installed in those buildings requiring fire protection. These systems are normally complete in themselves. For example, independent wiring systems are utilized between the various sensing stations and the central monitor. While this may, in some instances, provide safeguards against rather improbable risks, it also makes such systems highly expensive. This expense is largely responsible for the fact that few residences are equipped with fire alarm systems.
An additional undesirable facet of such installations is their almost complete lack of adaptability to changing conditions. Thus, a space once relatively free from fire hazards may now be employed for storage of inflammable goods. Rewiring would then be required to provide the necessary protection.
It is, therefore, an object of the present invention to provide an improved automatic signal system.
Another object of this invention is to provide such a system wherein special wiring is not required.
Another object of this invention is to provide such a system which is less expensive than those systems presently in use.
Another object is to provide such a system which may be adapted to changing conditions without wiring alterations.
The manner in which the foregoing objects are achieved will be more apparent from the following description, the appended claims and the figures of the attached drawings, wherein:
FIG. 1 is a schematic diagram of a transmitter usable in the present invention;
FIG. 2 is a schematic diagram of a receiver usable in the present invention, and
FIG. 3 is a schematic diagram showing the manner in which a transmitter and receiver are connected into a household wiring system to accomplish the objects of this invention.
The objects of this invention are achieved by utilizing the normal household wiring system as the signal wiring system of the fire alarm of this invention. This is achieved by means of a transmitter unit which is plugged into the house wiring system and generates over the house wiring a signal upon actuation by a heat source such as a fire. The signal which is so generated is received from the house wiring by a receiver, which thereupon sounds an alarm or takes other action.
The operation of the transmitter employed with this invention will be more readily understood by reference to FIG. 1 which illustrates a standard home convenience outlet 10, connected to the house wiring system 12, 14, carrying a normal potential of 110 volts. The transmitter of this invention is connected to the house wiring by means of a plug 16. A pentode 18 is employed as an oscillator. The filament 20 of tube 18 is energized by connecting it across the main power source but in series with resistor 22. A diode 24 and a filter capacitor 26 "ice provide the necessary DC. voltage. Resistor 33 and capacitor 34 comprise a grid leak detector which controls the sensitivity of tube 18 and also provides the negative bias for the tube. Choke coil 36 and capacitor 38 provide the inductive kick necessary to begin oscillation. The resonant circuit of coil 28 and of capacitor 4% is designed to resonate at a suitable frequency which may be, for example, on the order of 220 kc. An output coil 42 is wound in flux-linking relationship around coil 28. Capacitor 44 is so selected as to prevent the cycle A.C. signal from the power line from entering the oscillator coil. However, capacitor 44 permits the radio frequency signal voltage to pass. The oscillator of FIG. 1 is energized by means of a thermostat switch 46. Switch 46 is so designed that when the ambient temperature reaches 130 F. the switch will close. This will energize the oscillating circuit and a radio frequency signal of approximately 200 kc. is then transmitted through condenser 44 and into the house wiring system.
FIG. 2 illustrates the receiver portion of this invention. A convenience outlet 5i which is similar to that shown in FIG. 1, is connected to the 110 volt house wiring shown as lines 52 and 54. The receiver of this invention includes a fuse 58 and a pilot light 69 for indicating whether or not the circuit into which the receiver is plugged is energized. A blocking capacitor 62 is connected in series with the line to prevent 60 cycle AC. from leaking into the receiver; however, capacitor 62 is of such value that the radio frequency signal generated by the transmitter of FIG. 1 is allowed to pass unblocked. The radio frequency signal passes into a transformer 64, which comprises a primary winding 66 and a secondary winding 68. Variable tuning capacitors 70 and 72 are employed-to tune the transformer to the desired frequency. The weakly received RF signal is partially boosted by transformer 64. It is then further amplified by passing it through a voltage doubler circuit. The voltage doubler circuit comprises diodes 74, 76, two filter capacitors 78, and a transistor 82. The operating voltage for the transistor is supplied by a transformer 84. The primary winding of transformer 84 is supplied by the mains voltage from plug 56. The secondary 86 supplies an alternating voltage which is rectified by diode 88. The amplified and rectified radio frequency signal from transistor 82 is utilized to actuate the relay coil 90. A capacitor 92 may be used to prevent chattering of the relay contacts 94, 96. When relay coil is energized, contacts 94 and 96 close. This energizes coil-98 of the succeeding relay. Upon energization of relay coil 98, relay contacts 100 and 182 close. This causes the load 164 to be connected directly across the house wiring voltage. Load 104 may be an alarm of any type such as a bell, buzzer, or light. It may be any combination of these as well as any other suitable device. For example, load 104 may be a solenoid operated valve for controlling water fiow to sprinkler systems.
FIG. 3 illustrates a common type of house electrical distribution system and indicates the manner in which the transmitter and receiver of this invention are employed therein. In the three wire system that is commonly employed, three lines 110, 112 and 114 are brought into the house through a breaker 116. Lines 112 and 114 are energized above ground potential and have 220 volts between them. Line is neutral and is grounded. The voltage between line 110 and either of lines 112 and 114 is 110 volts. Each of the three entrance wires connects to a corresponding copper bus 118', 112', 114' located in a standard distribution panel. Each of the energized busses, 112' and 114' energize a plurality of feeder circuits through a fuse or a breaker in each of the circuits. It will be readily understood by an inspection of FIG. 3, that all of the outlets of any one residence will be electrically interconnected with one another through the wiring system. It is this fact which makes the invention of such great importance. Any number of locations throughout the house or its out-buildings may be monitored for fire by merely plugging a transmitter constructed in accordance with the prior description into a convenient outlet. Furthermore, the transmitters which are so placed may be monitored from any location where it is possible to plug the receiver into a convenience outlet. Furthermore, the number of monitoring stations is unlimited, as is the number of transmitting stations. As an example of the usefulness of this invention, several transmitters of the above-mentioned type may be plugged into suitable outlets located in various portions of a barn. A receiver could then be installed in a bedroom of the farmhouse, for example, or possibly in other locations throughout the house.
While this invention has been described with particular reference to a fire alarm system, it is to be understood that the invention is not in fact so limited. This invention may have utility in any application where it is desired to monitor information from different locations and to do it cheaply and effectively.
Furthermore, the above description has referred to transmitters and receivers as independent units. It will be readily apparent to those skilled in the art that the functions of such units may be combined into single devices under the general term of transceiver" without departing from the basic teachings contained herein.
In the specific embodiment, a thermostat switch has been described in combination with the transmitter. However, it is to be understood that if other variables besides temperature are to be monitored, suitable switching schemes may be arranged for this purpose. For example, if it is desired to turn on the lights as night approaches, the thermostat switch could be replaced by a photo-sensitive tube. By using simple mechanically-actuated switches at windows and doors, a very effective burglar alarm system may be constructed using the principles of this invention. Many other variations and modifications of this invention will also be apparent to those skilled in the art.
The invention, therefore, is to be construed as limited only by the scope of the following claims.
What I claim as new and desire to secure by Letters Patent of the United States is:
1. A receiver for utilizing high frequency signals re ceived over a normally low frequency Wiring system which comprises: connecting means adapted to connect said receiver to said wiring system; a primary winding in electrical series relationship with said connecting means to be energized therefrom; a blocking capacitor in electrical series relationship with both of said connecting means and said primary winding to pass said high frequency signals and block passage of low frequency current; a secondary winding in flux-linking relationship with said primary winding; a voltage doubling circuit energized by said secondary winding and adapted to provide a rectified output voltage exceeding the effective voltage from said secondary winding; an amplifier in amplifying relationship to said rectified output voltage to produce an amplified voltage therefrom; a first relay coil in energizable relationship from said amplified volt- 4 age; first relay contacts adapted to close upon energization of said first relay coil; a second relay coil in series with said first contacts and adapted to be energized from said low frequency wiring system; second relay contacts adapted to close upon energization of said second relay coil; and indicating means inseries with said second contacts and adapted to be energized from said low frequency wiring system.
2. A signal system for use with a relatively low frequency power wiring system which comprises: a transmitter for generating and transmitting high frequency signals over said wiring system upon occurrence of a preselected physical phenomenon which comprisesconnecting means adapted to connect said transmitter to said wiring system, switch means responsive to said physical phenomenon and connected to be energized from said connecting means, high frequency oscillator means in electrical series relationship with said switch means to be energized from said connecting means upon occurrence of said physicalphenomenon, and electrical conductor means interconnecting the output of said oscillator means with said connecting means to apply said signal to said wiring system; and a receiver for utilizing the high frequency signals received over said wiring system which comprises connecting means adapted to connect said receiver to said wiring system, a primary winding in electrical series relationship with said connecting means to be energized therefrom, a blocking capacitor in electrical series relationship with both of said connecting means and said primary winding to pass said high frequency signals and block passage of low frequency current, a secondary winding in flux-linking relationship with said primary winding, a voltage doubling circuit energized by said secondary winding and adapted to provide a rectified output voltage exceeding the effective voltage from said secondary winding, an amplifier in amplifying relationship to said rectified output voltage to produce an amplified voltage therefrom, a first relay coil in energizable relationship from said amplified voltage, first relay contacts adapted to close upon energization of said first relay coil, a second relay coil in series wth said first contacts and adapted to be energized from said low frequency Wiring system, second relay contacts adapted to close upon energization of said second relay coil, and indicating means in series with said second contacts and adapted to be energized from said low frequency wiring system. i, i
References Cited by theExaminer UNITED STATES PATENTS 2,177,843 10/ 1939 Seeley.
2,312,127 2/ 1943 Shephard 3403 10 2,484,700 10/ 1949 Fitzsimmons.
2,580,539 l/1952 Goodwin 340-3l0 2,799,853 7/1957 Colwell et a1 340--310 2,860,324 11/1958 Berger et a1. 340-310 2,913,711 11/1959 Polyzon.
2,992,412 7/1961 Spindler 340-171 3,035,251 5/1962 Inderwiesen 340-171 NEIL C. READ, Primary-Examiner. R. MQANGUS, H. I. PITTS, Assistant Examiners.