Abstract: A low battery voltage indicator is for use with remote control keyboards which are not linked by a cable to a power supply. Such keyboards contain their own power and are widely used. Remote keyboards that are infra red linked to personal computers are widely available. Similarly, remote control TV channel selectors utilizing infra red links are extensively used and sold. A majority of these devices utilize a battery to power the transmitter for the infra red communication link from the remote unit to the base unit. This is an improved low voltage indicator circuit and technique that utilizes the infra red link and the key encoding circuits of the keyboard to transmit to the base station a key code indicative of the fact that low battery voltage exists. At the base station, the key code is received and is looked up in a table that identifies the key code as a low battery voltage indication. This causes the base station to flash a low battery voltage warning message on the display screen.

Abstract: A microcomputer controlled monitoring system and method for detecting an electrical open, shorted or operative condition of an electrical load. A load switch circuit couples the load to a common voltage line and is controlled by a single drive line from a microcomputer controlled load monitor circuit.

Abstract: An indicating system includes first and second voltage comparators, first and second output circuits which are respectively supplied with output signals of the first and second voltage comparators, and first and second indicating elements which are connected to a common output terminal of the first and second output circuits. A first input terminal of the first voltage comparator is supplied with a first reference voltage, and a second input terminal thereof is supplied with a control signal. A first input terminal of the second voltage comparator is supplied with a second reference voltage, and a second input terminal thereof supplied with the control signal. When the voltage level of the control signal is higher than the first reference voltage, the first output circuit causes a current of a first polarity to flow to the common output terminal. As a result, the first indicating element is lit up, and the second indicating element is not.

Abstract: A portable light for emergency illumination which is activated in response to the sound emitted by a smoke alarm device, which light has an efficient and reliable battery conserving circuit. The present light includes a switch interconnecting a battery and a light bulb for selectively activating the light bulb and a circuit interconnecting a microphone and the switch for selectively activating the switch in response to a smoke alarm signal. A strobe circuit interconnects the source of power and the circuit for periodically activating the circuit which, therefore, draws power for only a small fraction of the time.

Abstract: A smoke detector utilizing a pulsing light source, a photo-voltaic cell, and an amplifier, in which the total current output on each light pulse is a function of the smoke concentration. In a preferred embodiment of the invention, the amplifier output current resulting from each light pulse is converted into an output signal which has a duration which is a function of smoke concentration.

Abstract: A sensor element responding to gases and/or vapors is heated in at least two temperature cycles continuously from a starting temperature value to an upper temperature value in accordance with a predetermined pattern which is optimized for selective gases. The temperature is lowered to the starting temperature value in accordance with the same or a different pattern. During the temperature cycles a signal which depends on the composition of the gas or vapor atmosphere delivered by the sensor element is compared in an electronic evaluation circuit to stored values which are characteristic for the presence of selective components in the gas and/or vapor.

Abstract: The subject of the invention is a circuit for monitoring the charge state of a battery for supplying voltage to an electrical consumer through a mode selector switch which may be switched from an OFF-state for disconnecting the electrical consumer from the battery into an ON-state for connecting the electrical consumer with said battery whereby in said ON-state different modes of operation of said electrical consumer are possible. The charge state of the battery is determined when the mode selector switch is in the ON-state and, when the voltage drops below an adjustable threshold value, an acoustic and/or optical indication is triggered after the electrical consumer is switched off. The circuit in the ON-state consumes only a very slight amount of energy and no additional energy in the OFF-state. In addition to the mode selector switch for switching the electrical consumer on and off, no battery test button or additional battery test position of the mode selector switch is required.

Abstract: A smoke detector indicator for a fire alarm system having an ON-OFF switch indicator system that permits the audio alarm to be turned off for false alarm situations, but has a visual indication that the system is not in operation. In a system including a circuit connecting a smoke detector, battery and an audio alarm, all in a single enclosure, the improvement comprises a switch in the circuit to open the circuit and prevent the alarm from sounding, and a visual indicator associated with the switch, visually apparent when the circuit is open, and not visually apparent when the circuit is closed.

Abstract: A diode failure detecting device in a rotary rectifier having fuses provided respectively for phases and connected in series to rectifying diodes. Light emitting diode circuits in one embodiment are connected in parallel respectively to the fuses which are arranged on the peripheral surface of a rotor. The LED's preferably emit light in different emission spectra when the respective fuses are blown out. An optical fiber sensor is provided on the side of a stator, for detecting when the LED's emit light and a photo-electric converter converts optical signals applied thereto through the optical fiber sensor into electrical signals through optical spectral discrimination separately according to the phases of the rectifier. A logic circuit determines the flow of over-current in the rectifying diodes from an output of the photo-electric converter. In a second embodiment, flags on the fuses are optically scanned to determine the presence of a blow fuse.

Abstract: An improved floating sensor for the detection of oil leaks at a water surface is provided wherein a cloth layer is affixed to the outside of a leak detector which, by capillary action, results in a threshold level of oil film thickness below which no alarm sounds and above which an alarm will sound. The invention provides means for the pre-selection of the thickness of oil film which will be detected and eliminates the detection of very thin, inconsequential oil leaks.

Abstract: Corrosion of a water sensor resulting from the passage of considerable electric current through it while it is in contact with water is prevented in a motor fuel filter equipped for water separation by interrupting or greatly reducing the current passing through the sensor after the sensor has given a signal indicating the presence of water in sufficient quantity to require draining soon. The warning provided to the vehicle driver is maintained thereafter either by a signal storage circuit (flipflop) or by causing current diverted from the sensor to flow through a substitution resistor or a shunt transistor.

Abstract: A programmable controller system is taught which uses an oscillator to provide a relatively low frequency low duty cycle series of digital ones and zeros to the gate logic of a load control device regardless of whether the device is in the ON or OFF state. These signals are electrically passed through the system which controls the load for such a short time that the load cannot change state because of electrical momentum and/or inertia thereof. The series of digital ones and zeros nevertheless do pass through the system and sensing means serve to test the correct operation of the output devices. As long as the oscillator generated signals continue to pass through the gate, the capacitor controlled sensing devices will be held in a state such as to provide no indication of failure.

Abstract: An overcurrent condition display suspended directly from a distribution cable for displaying overcurrent conditions in the cable and for promptly locating spots of accidents due to overcurrent conditions comprises a current sensor section having a current transformer, a drive section provided with a drive element adapted to be driven by the sensed overcurrent and with a force storage member adapted to be actuated by the drive element and to act as a restoring member as well for the drive element, a drive-transmission section actuated by the force storage member and a display section having a display tube with a transparent bottom, a viscous fluid stored in the tube and a display element connected to the drive-transmission section for vertical motion through the fluid. The overcurrent condition is displayed when the display element is hoisted by the drive-transmission section.

Abstract: A contact monitor and annunciator unit for providing a persistent warning in the event one of a selected number of event monitoring circuits associated with a mobile refrigeration system opens. The unit includes a number of warning circuits that are electrically isolated from the monitoring circuits by optical isolators and a separate power supply so that the initial cause of a shut down due to abnormal operating conditions can not only be annunicated but also differenciated from a shut down caused by a momentary power failure.

Abstract: A system senses alternating current in a conductor, such as a main line supplying electrical power to a home, and responds to the sensed current as by providing a warning signal when the sensed current exceeds or is less than a preset value for a predetermined short period of time. The current sensor itself is a simple coil of wire, either with an air core or a partial ferromagnetic core, which can be easily operatively associated with the current carrying conductor without the need for disconnecting the conductor from its terminals and which when installed does not present the hazards associated with current transformers.

Abstract: A fuse-type circuit breaker having a fuse link which is manually pivotal in a housing between an on position and an off position. The fuse link has contact caps which, when in the open position, short-circuit two current contacts which are fixed to the housing. Also provided is an operating state indicator device which includes a light source for the fuse link. The indicator device, at least in the on position, is electrically connected with the two contact caps of the fuse link and with the two current contacts. The indicator device is in parallel with the latter and is provided with a very high electrical resistance relative to the fuse link. The indicator device is in the form of a blinker which incorporates a capacitor, a first diode connected ahead of the capacitor, and a charging resistor as well as a glow lamp connected in parallel with the capacitor and in series with a discharging resistor.

Abstract: A novel fire alarm system with a plurality of smoke detectors which are adapted to be installed in different locations are connected through a data transmission line to a receiver where the smoke density signals transmitted from the respective smoke detectors and indicative of the density of smoke in the corresponding locations are processed for determination of fire presence. The receiver is provided with fire judging circuit which identifies the presence of fire only when the smoke density detected by any one of the smoke detectors exceeds a reference density level and when such smoke density lasts over a reference time period. Thus, the information from each smoke detector is analyzed with respect to the smoke density and the time period over which the smoke density of significant level lasts. Accordingly, a reliable detection of fire is effectuated.

Abstract: The present invention relates to a fuse loss indicating system for monitoring the condition of a plurality of fuses in an electric circuit. The indicating system includes a plurality of individual indicator circuits, one for each fuse to be monitored. Each indicator circuit includes an optical isolator for electrically isolating the indicator circuit from the monitored circuit. When a monitored fuse blows, the associated optical isolator triggers a flip flop to generate a fuse loss signal to cause a warning LED to light and alert an operator as to which fuse has blown. In its preferred embodiment, the fuse loss indicating system is utilized to monitor the fuses in an SCR motor bridge circuit. In this embodiment, the fuse loss system also generates a bridge disable signal when a fuse blows to cause a bridge lockout circuit to disable the gating signals to the SCR's, thereby disconnecting power from the motor.

Abstract: A power supply control circuit for controlling power supply through a power switch to a battery-operated circuit. The control circuit includes circuitry for keeping the power supply to the battery-operated circuit for a predetermined holding time after the power switch has been turned off, the holding time being reduced as consumption of the battery develops.

Abstract: A gas flowmeter includes an oil-filled tube coupled to the gas flow line and a float lifted by gas flow. An LED lamp transmitter and a photoresistor receiver are coupled to a guard telescoped over the tube. The LED lamp has an integrated concentrating lens to define a concentrated sharp beam passing through a small barrel located in a guard slot for close coupling the light beam to the tube. The photoresistor receiver includes a similar barrel in an opposite slot in accurate alignment with the transmitter barrel. The receiver includes a photoresistor connected in a dividing network to define an input node to a regenerative "Schmitt" switch which actuates a solid state control relay to indicate a limit position of the float. A mounting plate has a correspondingly mounted light transmitter housing and photoresistor housing. The housings are formed from the same casting. The housings include similar integral clamping tongues located in slots on the opposite sides of the guard.