Abstract: A photoelectric smoke sensor wherein a photo diode having a junction capacitance of 100 pH or less is employed and a resistor having a high resistance value of the order of mega-ohms is connected in series with the photo diode to obtain a photo output through the resistor, so that the voltage of the photo output may be sufficient to be directly subjected to comparison by the comparator without high-gain amplification even if the driving current for a light emitting diode is reduced. This enables omission of a high-gain amplifier and accordingly enables omission of a shield case for the circuits of the sensor which has been required to eliminate noises.

Abstract: An apparent-wind direction indicator for day and night sailing has a hollow conical section with an axial counterbalancing rod extending forward from the apex of the cone. The wind direction indicator is mounted to pivot about a hollow tube extending above the top of a mast. The top of the hollow tube extends within the conical section. An electric lamp is mounted at the top of the hollow tube within the hollow conical section and is illuminated by means of wires through the tube connecting to the ship's power supply. A substantial portion of the underbody of the hollow conical section is made of light-transmitting material so that the light from the electric lamp will be visible from the deck below. The light-transmitting material, as well as the conical section is formed to suggest an arrow to indicate the direction of the wind to the deck below.

Abstract: A central smoke detection system for a building having multiple rooms utilizes low cost commercial smoke detectors in each room. Each detector includes a steady high current alarm mode, a low current idle mode and a high pulse current test mode. A central power source supplies power to the detectors via one common lead and a separate power lead to each detector. A resistor in each power lead at the central location provides for monitoring of the mode of each smoke detector. A central monitor operates a visual smoke alarm responsive to the steady high current mode which indicates the room in which a detector is in the alarm mode and a visual fault alarm responsive to the absence of the high test pulse current indicating the room in which a detector is inoperative. A common central smoke and fault alarm, both audible and visual is also provided.

Abstract: Apparatus for monitoring electrical cables for the presence of moisture within the cable along the full length of the cable and at specific points such as splices along its length comprises a pair of dielectrically separated conductors arranged along the length of the cable for communicating between a central station and remote stations along the length of the cable at the specific points to be monitored. The remote stations each include a further dielectrically separated pair of conductors for sensing moisture at the point and signals along the first pair of conductors to the central station. The central station detects moisture by an increase in current in the conductors and also detects a signal from remote stations.

Abstract: A pellistor type combustible gas detector including a Wheatstone bridge therefor fed from a voltage regulator and a constant current generator. Two comparators detect, for example, 50% to 75% of the lower explosive limit of the gas to be detected and 25% thereof, respectively. Latches keep indicator lamps lit and alarms turned on. The latches are selectively inhibited or not to check front panel and remote milliammeters calibrated in percent of gas concentration, and to test alarms. A gauged switch performs these and operating and reset functions. A circuit failure detector, lamp and alarm are also provided.

Abstract: An add-on fault indicator comprising a magnetic reed switch (22) and a lamp (24) connected in series across relay contacts (10, 12, 14) with the reed switch mounted by a clamp (34) contiguous to the outer surface of the metal coil shell (6) so as to be closed by the magnetic field when the coil (2) is energized. A normal operation indicator lamp (26) is connected in series with the relay contacts to indicate closure of the latter to energize a load (20). Fault indicator lamp (24) lights if the contacts do not close when the coil is energized but is shunted by the contacts to remain unlighted when the contacts close properly.

Abstract: A power outage indicator utilizes a smectic liquid crystal display cell, capable of storing information indefinitely, to provide a visual indication, of predetermined form, that power to a given installation has been interrupted. Prior to installation, the smectic liquid crystal display of the power outage indicator is heated and an appropriate voltage placed between the display electrodes to cause the liquid crystal material to align homeotropically, as the liquid crystal material cools to the smectic state; a clear stable texture results. Upon loss of power, stored charge, as in a storage capacitor, is enabled to flow through at least a portion of at least one of the display electrodes, reheating the liquid crystal material therebetween and, upon cooling without an applied field, converts a portion of the liquid crystal layer to a state having differing light-propagation properties than the remainder of the display.

Abstract: A pressure transducer, such as a microphone, is placed in proximity to the blades of a fan, such as a fan used to cool electronic equipment. As each blade passes the transducer, a pressure wave is generated that is converted into an electrical pulse by the transducer. Circuitry responsive to those pulses signals an alarm if the fan is not operating properly.

Abstract: A miniaturized electronic apparatus having an alarm sound generating function comprises an alarm sound data memory, in which alarm sound data for a plurality of different alarm sounds are memorized. Peculiar alarm sounds can be preset for each season or month or weekday so that upon reaching of an alarm time in the corresponding season or month or on the corresponding weekday it is selectively read out from the memory to produce the corresponding alarm sound from a sound generator. A designated order of the plurality of different alarm sounds can also be set in the apparatus.

Abstract: A portable, battery powered smoke detector in which the operative components are compactly and efficiently arranged in such a manner that they may be housed in a pocket-sized casing approximating the shape and size of a cigarette package. A further embodiment shows an efficiently organized arrangement of the smoke detector components in a telephone set.

Abstract: An automatic liquid level indicator and alarm system (10) that automatically emits an alarm when liquid in a vessel reaches a preselected low or high level. The system (10) is particularly adaptable for use on petroleum storage tanks (50) of the type found on petroleum tank farms. The system (1) comprises a low-level and a high-level permanent magnet (10) (11); a low-level and a high-level magnetic sensor (24) (25); an encoder-RF transmitter (15) (16); an RF receiver-decoder (18) (19); an alpha-numeric display (20) and an audible alarm (21). The magnets (10) (11) are attached to an existing movable tape (31) whose position at any instant is relative to the position of a float (41) within the tank (50). The magnets (10) (11) are located at positions indicative of the preselected low or high level marks.

Abstract: A gas detector comprising a main gas sensing element showing the resistance change to both the detection target gases, such as methane, butane, hydrogen gases, and non-target gases such as alcohol steam, smoke; an auxiliary gas sensing element showing the resistance change primarily to non-target gases along; the first comparator to which the output based on the resistance change of main gas sensing element is received as input in parallel form; the second comparator with lower reference electric power than that of the first comparator; a gate circuit to cut off the alarm actuating signal from the second comparator by means of output induced by the resistance change of auxiliary gas sensing element. Either the output from said gate circuit or the output from said first comparator is used for alarm actuating signal of alarm circuit.

Abstract: An ionization detector of the type having a housing with electrodes and a radiation source for causing ion current flow between the electrodes, collector means for detecting, by a change in voltage, a drop in ion current flow, and means responsive to a predetermined change in collector voltage to provide an output signal, in which a test electrode is provided in the housing and means is provided for applying to the test electrode a predetermined voltage of a value that causes said predetermined change in voltage at the collector, whereby said output signal is provided when said predetermined voltage is applied to the test electrode if said detector is operating satisfactorily.

Abstract: In a monitoring system for the gates of a mine lift shaft, each gate has a switch and a square wave is generated in a signal station and connected to a transistor inverter beyond each switch. When the switch is in the closed (safe) position, the transistor inverter is connected in circuit and the inverse of the waveform is transmitted back to the signal station. When the switch opens the transistor is shorted out and thus the returned waveform is in phase with the transmitted waveform. The various conditions which may be received at the signal station are detected and only if the switch and cable are operating correctly is the gate closed condition indicated. The use of a square wave and a changeover switch ensure that both conditions of the switch produce a definite signal at the signal station, thus any failure in the cable or switch prevents the received waveform from being the inverse of the transmitted waveform.

Abstract: In an electrical power transmission system, transmitter-receiver pairs at stations which communicate with similar pairs at other stations to block tripping of circuit breakers or for other control functions are periodically tested. An electrical circuit periodically activates a transmitter to send a test signal from a first station over a power line to a receiver at another station in the system. The receiver at the other station activates the associated transmitter in response to receipt of the incoming signal to send a signal back to the receiver of the first station. If this cycle is not completed in a specified time, indicating loss of communication between the two transmitter-receiver pairs, an alarm is activated.

Abstract: An ionization type smoke detector (10) includes a chamber having a measuring electrode (12), the voltage on the measuring electrode being a function of the concentration of smoke in the chamber, and further includes a comparison device (A3) for comparing the voltage measured on electrode (12) at two different times, and an output device (K) for producing an output signal if the voltages differ by a predetermined value.

Abstract: Message character image projection control means for establishing conditions which simulate the eye glass or contact lens needs of an individual utilizing acousto-optic light refracting principles wherein a pair of acousto-optic cells, positioned in the line of sight of an observer, are controlled in a manner necessary to permit a viewing of the characters with a desired degree of sharpness and clarity.

Abstract: The invention relates to a device for checking a plurality of indicator lights, wherein the intensity passing through each indicator light is sequentially measured and the measurements are compared with nominal intensities. The invention is more particularly applicable to the checking of the indicator lights of devices monitoring functional members.

Abstract: A debris alarm device for use with a particle analyzing apparatus of the Coulter.RTM. type generates discrete particle pulses in response to liquid suspended particles passing through a sensing aperture, the debris alarm comprising threshold circuitry for generating a threshold pulse for each particle pulse; circuitry for generating, for each threshold pulse, a normal pulse of predetermined duration; a first current source and a second current source for providing currents of opposite polarity to an integrator, when said current sources are triggered, respectively, by the threshold pulses and the normal pulses; and debris indicator circuitry, including an alarm, for determining when the output voltage of the integrator, which initially is set to zero, falls out of a predetermined voltage window.

Abstract: Alarm-indicating gas detection apparatus including a first semiconductor gas-sensing element having one electrical property which varies significantly with increasing concentrations of a first undesirable gas and less significantly with increasing concentrations of a second undesirable gas and a second semiconductor gas-sensing element having the same electrical property which varies significantly with increasing concentrations of the second gas and less significantly with increasing concentrations of the first gas. The electrical property of both gas-sensing elements tends to vary similarly with age and with changing conditions such as temperature and relative humidity. A compensation system is used to cancel out errors due to variations in the electrical property. Threshold circuits are used to distinguish between first and second undesirable gases and to generate alarm signals.