Abstract: A testing circuit for an alarm system is disclosed. The testing circuit is operable in an alarm system that includes a microphone for receiving an audio sound and a detector/generator for detecting audio characteristics in the audio sound corresponding to breaking glass and for generating an alarm signal in response thereto. The audio characteristics corresponding to breaking glass include first and second frequency components in timed relation, wherein the first frequency must be detected prior to the second frequency for an alarm to be generated.

Abstract: An ionization chamber for use in a smoke detector includes first and second outer electrodes and a non-reflective center electrode. The non-reflective center electrode can be formed as a metal electrode having a non-reflective coating or as a non-reflective, conductive plastic elements. The ionization chamber can be incorporated into combination smoke detector which includes a photoelectric sensor. A non-reflective center electrode, associated with the ion-type sensor is symmetrically located in the detector and displaced from the photoelectric sensor.

Abstract: A fire alarm system includes a control unit which communicates with a plurality of spaced apart smoke detectors by a bi-directional communications link. The smoke detectors are separate from one another, and spaced apart, and are associated together in different, overlapping groups. Each group of detectors is physically arranged with the members of the group adjacent to one another in a relatively localized area. Signals from the detectors are transmitted to the control element for processing. The control element squares each of the signals for a given group, sums those signals and then takes a square root. The resultant processed value is associated with a selected one of the detectors of the group. Similar processing takes place for each of the groups. As a result of the processing, each of the detectors has associated therewith a processed smoke value which takes into account not only values received from the associated detector, but also values received from one or more adjacent detectors in a group.

Abstract: A self-testable photoelectric smoke detector incorporates a housing which defines an internal smoke chamber. The housing carries a laser diode and a radiation sensor along with a supplemental source of test radiant energy. When a test is initiated, the operational characteristics of the laser diode are monitored simultaneously with energizing the source of test radiant energy. Signals from a scattered radiant energy sensor are evaluated via control circuitry, along with signals indicative of performance of the laser diode to determine whether or not the laser diode as well as the radiation sensor are functioning properly.

Abstract: A noise immune detection system includes a plurality of detectors that generate respective indicia representative of adjacent ambient conditions. A communications link extends between the detectors. A control element is coupled to the link to receive and process the indicia and to adjust an alarm threshold level in response to noise levels in the system. Respective indicia are filtered twice by the control element. In the presence of noise, as reflected in relative values of the filtered values of the indicia, the threshold value is automatically increased.

Abstract: An alarm system for producing substantially synchronized visual output indicia of the alarm condition includes a common source of pulses which is activated in response to the presence of the alarm condition. The common source of pulses generates a trigger pulse train having a predetermined period. The trigger pulse train is fed, via power supply lines, to a plurality of visual output devices which can be triggered in response to the arrival of each of the pulses in the train thereby producing a synchronized plurality of visual indicia indicative of the alarm condition. The output devices will produce an essentially synchronized plurality of visual indicia in the presence of the alarm condition even in the absence of the trigger pulse train.

Abstract: A fire alarm system utilizes outputs from different types of fire sensors, such as photoelectric smoke sensors or ionization type smoke sensors and combines those outputs by subtraction so as to establish a delay interval during which one or both of the sensor output values must exceed a predetermined threshold value to cause the system to go into an alarm condition. Prior to subtracting the outputs from one another, each of the outputs can be raised to a predetermined exponential value so as to emphasize the effects of larger sensor output values. Where the two types of fire sensors each are generating outputs indicative of a fire condition, the calculated delays will be relatively short. In instances where only one of the two sensors is generating an output indicative of a fire condition, the calculated delay will be longer, so as to inhibit false alarms.

Abstract: A multiple element reflector usable with an elongated light source in a strobe unit provides wide fields of view in both horizontal and vertical directions when the unit is mounted on a wall. The reflector includes a first, elongated, curved reflector element which extends generally parallel to the elongated light source. At least second and third centrally located reflector elements extend between the first reflector element and the light source. The first reflector element provides illumination generally in horizontal and vertical directions perpendicular to the elongated source. The second and third centrally located reflector elements provide illumination in a direction generally along the elongated source.

Abstract: An apparatus and a method for addressing a plurality of spaced-apart detectors or control units in a multiple zone detection system shortens the time needed for a centrally located control element to communicate with the detectors or units. The control element addresses a plurality of units simultaneously by means of a serial bidirectional communications line. Information can be transmitted time serially to each of the addressed units which is associated with a respective time interval. The addressed units can return, time serially, on the serial communication line a plurality of indicia. The control element associates each indicium with a respective detector by means of the indicium's position relative to other returned indicia.

Abstract: A communication system includes a control element, a bidirectional communications link, and one or more devices coupled to the link. The control element, via driver circuits, reversibly applies a predetermined potential to the link for the purpose of energizing the one or more devices as well as communicating therewith. The devices can respond at appropriate time intervals. During the responding time intervals, the control element can continue to supply power to the devices.

Abstract: A compensated ionization-type sensor includes spaced apart active and reference electrodes. A center electrode is disposed between the active reference electrodes. A compensating electrode is disposed adjacent to the center electrode and, capacitively coupled thereto. The compensating electrode is electrically coupled to the active electrode. A compensating screen with a selected potential applied thereto surrounds the electrodes to compensate for velocity of the ambient atmosphere.

Abstract: An alarm system which incorporates a large number of ambient condition sensors makes a determination as to the existence of a predetermined alarm condition by detecting respective ambient conditions from each member of a group of sensors. The indicators from the plurality of sensors are each raised to a respective predetermined exponent and summed together. The resultant sum is compared to a predetermined threshold to determine whether or not the alarm condition is present. The detectors can be spaced apart from one another in a selected region and coupled to a central control unit by a bi-directional communications link. Running averages of sums can be formed to provide filtering or smoothing or trend analysis.

Abstract: A right angle clamp is usable for mounting a condition sensor to an apparatus, such as a valve and the like. The clamp includes a bracket having first and second sides. The first side has a pair of elongated slots therein for receipt of a pair of straight-bolts. The bolts pass through the yoke of an associated valve, between the yoke uprights and the valve stem, and are secured to a substantially U-shaped, elongated retaining member having an open end. Each bolt is secured to the retaining member by threaded nut. A substantially U-shaped reinforcing member is positioned between the retaining member and the nut to prevent distortion of the retaining member when the retaining member is in tension. The elongated retaining member allows for easy installation and adjustment of the clamp.

Abstract: Wire terminal clamp having a wire receiving means situated in a surface, a wire clamping member and a means for moving the wire clamping member across the surface, so that when the wire clamping member is moved in one direction a wire end can be clamped and when the wire clamping member is moved in an opposite direction any wire end that is clamped can be released.

Abstract: A multiple element reflector usable with an elongated light source in a strobe unit provides wide fields of view in both horizontal and vertical directions when the unit is mounted on a wall. The reflector includes a first, elongated, curved reflector element which extends generally parallel to the elongated light source. At least second and third centrally located reflector elements extend between the first reflector element and the light source. The first reflector element provides illumination generally in horizontal and vertical directions perpendicular to the elongated source. The second and third centrally located reflector elements provide illumination in a direction generally along the elongated source.

Abstract: A detector supervision system usable with detectors or sensors formed with a removable head and a surface mountable base includes an energy storage device which is carried on each base. The energy storage device is either a capacitor or an inductor, and is coupled to one or more of the terminals of the base. A conducting spring member is also carried on the base, attached to one of the terminals. The spring member is in a first position when the head is attached to the base. The spring member moves to the second position in response to the head being removed from the base. Detection circuitry can detect the presence of one or more energy storage devices which are switched into communication lines between detector bases in response to one or more of the heads being removed. The detection circuitry can signal a central control panel that one or more of the heads has been removed from a respective base.

Abstract: An isolation circuit, which draws essentially zero current in a normal or stand-by state, uses a normally closed relay in combination with a storage element. A capacitor can be used as the storage element to energize the relay, using previously stored energy, in the event that a communication line to which the isolator is coupled exhibits a short circuit or low voltage condition. In this instance, the prestored energy on the capacitor activates the relay for a predetermined period of time, thereby open circuiting the communication line. When voltage is reapplied to one side of the isolator circuit, the relay is continuously energized and maintained in its open circuit condition until the low voltage or short circuit has been remedied.