Abstract: A detection circuit particularly adapted as a smoke detector employes a minimum number of components by a CMOS integrated circuit which receives directly the output of a smoke detector on one of the inputs of an input comparator circuit which provides static input protection and a high input impedence by employing thick oxide layer over the gates of the comparator transistors. The CMOS chip also directly supplies operating current for a mechanical or piezoelectric horn. Further features include a clocked low voltage alarm; a buffer stage to permit the interconnection of a number of different detector circuits in common to a single input/output lead; and a visual LED indicator to indicate that the circuit is operating and to provide a visual indication any time the alarm condition for the circuit has been actuated.

Abstract: A digital alarm system for monitoring a variable process signal utilizing a variable, digitally controlled alarm hysteresis capability. The system includes a means for establishing a preselected count level at which an alarm condition occurs. The preselected count level may be established in a high alarm or a low alarm state depending upon the process signal being monitored. Digital signals representative of the process variable are compared with the preset count level signals and upon a coincidence, an output signal is generated to provide alarm signals and also to reset the preselected count level signal to a second preselected count at a level which is a wide variation from the original preselected level so a relatively large change in the process signal occurs before the system is reset to its original alarm condition.

Abstract: Sensing apparatus for monitoring the operation of an electrical appliance. The sensing apparatus is plugged into a standard electrical outlet and the appliance to be monitored is plugged into the sensing apparatus. The appliance current flows through a transformer in the sensing apparatus. Detection circuitry including a comparator produces one signal when current flow through the transformer is negligible (appliance off) and another signal when the current flow through the transformer is significant (appliance on). Transistor circuitry connected to the detection circuitry produces a pulse at one output terminal on a transition from the one signal to the other signal from the detection circuitry (appliance turned on) and produces a pulse at another output terminal on a transition from the other signal to the one signal from the detection circuitry (appliance turned off).

Abstract: The present invention comprises computer system equipment useful for detection of faults in data transmission within a computer system. Fault detection is accomplished by monitoring the current flow through a digital signal source means, which is characterized in that it only draws significant current during a non-transition period when a fault condition occurs.

Abstract: The present electronic indicator or display device is equipped with adjustable upper and/or lower limit value markers to provide a respective alarm if such limit values are exceeded or not reached. The display itself comprises an electronic circuit and optical display elements such as light emitting diodes connected to the display circuit. An input to the display circuit is adapted to receive rated or limit value input signals which are displayed as respective markers and the position of which is adjustable. A time multiplexing circuit controls the timed sequence of the signals supplied to the display elements. A comparator compares the measured signal value with the rated value or values and monitors the proper function of the system.

Abstract: A battery-powered fire alarm including a smoke detector circuit, a controllable horn circuit and a battery monitoring circuit. The smoke detector employs a pair of complementary field-effect transistor switches with gates respectively connected to an ionization chamber and a potentiometer of a Wheatstone bridge circuit connected across the battery. The field-effect transistors are biased off to minimize standby power consumption and are connected such that the threshold voltages thereof are offsetting to minimize supply voltage sensitivity of the detector. When the voltage from the ionization chamber assumes a value approximately equal to a preselected alarm voltage at the potentiometer, both field-effect transistors turn on to energize an alarm circuit to sound an alarm. Hysteresis circuitry is provided to ensure that the complementary switches, once turned on, will not turn off and thereby terminate the alarm until after the alarm condition has terminated.

Abstract: A method of and a device for monitoring poly-phase currents in poly-phase equipment, in which a phase signal representative of the current in each phase of the equipment is obtained, the phase signals multiplexed so as to obtain a single multiplexed signal, and the multiplexed signal then processed to extract from it an output signal or signals representative of, for example, overload, unbalance, earth fault or short circuit conditions.

Abstract: A thermostat monitoring and controlling the temperature of produce ripening within an enclosure and featuring a bridge circuit sensing errors between the actual and desired temperatures in which the desired temperature is selected directly in units of degrees. A bridge amplifier having feedback maintains the bridge in electrical balance to avoid errors due to changes in bridge component self heating. An error detection circuit having a single control simultaneously selects upper and lower error limits centered on the desired temperature, in units of degrees. The circuit indicates whenever the actual temperature goes outside these limits. An alarm circuit indicates a temperature error or a power failure in the thermostat at the thermostat and at a remote location. This circuit utilizes an alternating current source which activates current direction-dependent indicators operating on alternate half cycles.

Abstract: A fail safe control circuit in which an input signal for initiating control of a potentially dangerous system is amplified only if it lies between given limits and also only if electrical power is being supplied to the system. The outputs of the amplifiers are monitored to check their correct operation, and two independent optical output signals obtained therefrom. The optical signals are arranged independently to operate switches in the system, such that both switches have to operate before the system can be actuated.

Abstract: A control system for automatic actuation of an exhaust blower associated with an internal combustion inboard marine engine. The control system includes a starter interlock circuit which prevents engine starting for a predetermined period of time to allow the blower to exhaust explosive fumes from the engine compartment and a low speed actuation circuit which operates in response to detection of engine speed below a predetermined level to actuate the exhaust blower. Also included is a emergency override of the starter interlock circuit.

Abstract: A circuit for detecting the discharge level of a long life battery, such as a lithium battery, in which the battery is periodically subjected to an increased load for short durations of time. The periodic increases in load allows the end of battery life to be predicted and detected prior to the time the battery is fully depleted. Forecasting the end of battery life ensures that the battery will have sufficient energy to reliably operate the discharge level detection circuitry before the battery is fully depleted.

Abstract: An alarm system for detecting a dangerous condition such as the increase in content of or the presence of toxic or inflammable gas in the air and giving a warning signal. The alarm system comprises an AC power supply, a full-wave rectifier connected to the AC power supply and rectifying alternating current from the AC power source into direct current. An AC bridge circuit connected to the AC power supply and includes a sensor element at least in one branch. An AC operational amplifier is supplied with power from the full-wave rectifier and receives an input signal which is the output signal delivered from the bridge circuit through a DC blocking capacitor. A thyristor is connected in parallel with the AC power supply, with its control gate connected to the output of the operational amplifier, and its main electrodes in series with an alarm indicator actuable when the thyristor is triggered into the conduction state.

Abstract: A capacitive shift fire detection device having a sample circuit and a reference circuit, each circuit having an air capacitor connected to an oscillator and a counter. The presence of particles of combustion in the ambient environment results in a change in the dielectric constant of the air dielectric of the sample capacitor, thus changing its capacitance. This change in capacitance is detected by an oscillator in the sample circuit, the mismatch of oscillators in the two circuits causing an exclusive OR-gate to go high, activating an alarm system.

Abstract: A dictation system having means for providing a signal for indicating when dictation which the system has been made operative to record on a recording medium is not being recorded on the recording medium because of a malfunction of the system or the improper operation of the system. The system includes means for providing a signal when the audio input to the dictation system and the audio input of dictation recorded on the recording medium are not in a predetermined relationship and means for providing said signal when dictation which the system has been made operative to record on the recording medium is absent from the recording medium for a predetermined length of time.

Abstract: A system for providing the suppression of voltage transients and other electromagnetic interference with positive indication of the operational status of the system. More particularly, a transient suppression circuit is utilized that suppresses and dissipates electromagnetic interference and transient energies that might be present; furthermore, there are detection and indicator circuits provided indicating to the user (1) whether or not each circuit is operative and functioning as it should, and (2) whether indeed transients are present in the system. A central concept of the system provides for transient detection and suppression capability, that detects transient activity occurring at voltage levels greater than the suppression threshhold established by the transient suppression circuit. The system or device can be used as an insertion device directly in the line, or can be disposed in shunt across the power lines.

Abstract: A first amplifier measures the instantaneous voltage across a resistor, connected in series with the electromagnet of a solenoid valve, as the current increases following energization of the electromagnet. A second amplifier measures the same voltage and stores the peak value in a capacitor. The two measured voltages are applied to a comparator which detects the difference, and generates an output, when operation of the electromagnet armature causes a transient reduction in the resistor voltage. Initial energization of the electromagnet sets a memory and starts a monostable timing period. The set output of the memory primes one input of an AND gate, the second input being inhibited by the monostable output during timing. If the electromagnet armature operates normally, the comparator output resets the memory and removes the AND gate priming signal prior to completion of the timing period.

Abstract: For monitoring the supervisory current in a communications line between a power source and a protected premises which forms a security protection circuit, monitoring apparatus utilizes sensitive solid state circuitry which appears transparent to the protection circuit. An operational amplifier input circuit protects the circuitry against component damage due to lightning, inherently rejects common mode errors due to noise, transients, and varying power supply voltage, and had an adjustable offset for line length compensation and circuit standardization. Voltage comparator circuitry indicates by digital signals the supervisory current level. After the operator conditions the apparatus for an abnormal current level which has been signalled, a lamp which blinks at a discernable rate is used to serve as a reminder of this state.

Abstract: When high-speed digital signals are transmitted through a slip ring connection between relatively rotatable systems, the slip ring connection is prone to brief interruptions of contact which introduce extra "ones" or "zeros" into the transmitted digital wave form. In this invention, the binary input signal is split into two paths, one-representing signals causing a current to pass through a first slip ring and zero-representing signals causing a current to pass through a second slip ring. On the output side of the slip rings, the passage of current through one slip ring or the other is used to reproduce the original binary signal; additionally, the combined current flow through both slip rings is used to generate an extra signal which, in the absence of current in either slip ring, indicates a fault.

Abstract: A monitoring circuit for monitoring a plurality of signals developed by remote sensors which preferably are capacitance probe sensors. The circuit is intended for use with a motor vehicle maintenance system employing capacitance probes to detect low and safe levels of oils and coolants in a vehicle engine. The monitoring circuit includes a constant voltage source with a voltage divider in circuit therewith to develop a plurality of reference voltage signals of predetermined values which are applied to respective inputs of a plurality of voltage comparators that receive, at their other terminals, condition-responsive voltage signals generated by a condition sensing circuit. The condition sensing circuit comprises a liquid level capacitance probe which generates intermediate, high and low voltage signals indicative of safe and low, respectively, levels of sense liquid.

Abstract: A monitoring device for monitoring incandescent lamps, especially in motor vehicles, is provided. A measuring resistor is connected in series with an incandescent lamp to be monitored. Means for monitoring the voltage drop at the measuring resistor are provided. The monitoring means comprises an operational amplifier to one input of which the connection between the measuring resistor and the incandescent lamp is connected and to the other input of which a voltage divider is connected which is mounted in parallel with the measuring resistor and the incandescent lamp. The voltage divider is formed of ohmic resistors, and the output of the operational amplifier controls an indicator means for generating an indication signal upon missing or excessively low voltage drop at the measuring resistor.

Abstract: In the system disclosed a driving circuit repeatedly scans along a plurality of aligned electrodes in an enclosure filled with ionizable gas, by sequentially grounding the aligned electrodes and repeating the process cyclically. Within each cycle, a pulse width modulator energizes an anode opposite the electrodes for a period of time corresponding to an input value. Sequential glow discharges thus occur between the cathodes and the anode over a portion of the anode length. The discharges occur with sufficient rapidity so that they are observed as an illuminated portion of a bar formed by the electrodes. A second set of electrodes is scanned and an opposing anode energized to produce two illuminated bands separated from each other. Desired upper and lower set point limits for the input quantity determine the lengths of the bands and the separation between them.

Abstract: Apparatus for the rapid monitoring of an alternating (a-c) variable with respect to amplitude, frequency and phase which includes a generator circuit for forming, from an actual a-c voltage imaging the monitored a-c variable, a reference a-c voltage of predetermined amplitude and frequency which is linked to the former in rigid phase relationship, and comparators for comparing individual signals of the generator circuit with the instantaneous values of the actual value a-c voltage, permitting recognition of disturbances in a time which is substantially shorter than one period of the a-c variable monitored.

Abstract: A multi-input signal comparator and indicator circuit for comparing a plurality of signal levels with a reference level and an indicator circuit arranged to respond to a comparator output signal for indicating an error in any of the comparator input signals. A high and a low comparator is used for each input signal to provide a "window" comparison while separate indicators provide a readout of high and low errors.

Abstract: A logic probe includes a first lamp for indicating an input voltage level above a first predetermined magnitude or upper threshold, a second lamp for indicating an input voltage below a second predetermined magnitude or lower threshold, and a pulse lamp for indicating the change in the input voltage level. Circuit means are provided to control the operation of the third or pulse lamp so that the lamp operates in accordance with the position of a selector switch. When the switch is in a first position, the pulse lamp will operate in response to a change in the input voltage level through either one of the thresholds, and when the switch is in the second position, the pulse lamp will operate only if the input voltage level transitions both thresholds within a predetermined time.

Abstract: Fault detection circuit which is intended to be included in an anti-skid control system for a braking system of a motor vehicle. The fault detection circuit is coupled between the sensor coil and tachometer portion of the anti-skid control system and detects if the sensor coil becomes: open circuited, shorted to ground, or shorted to a power supply. If any of the aforementioned conditions arise, the fault detection circuit provides an output signal for indicating such a condition to warn the driver of the vehicle that the anti-skid control system is non operative. A low pass RC filter is utilized to limit the input signal amplitude developed across the sensor coil to a constant value which is determined by the time constant of the low pass filter. Upper and lower references voltages can be established and compared to the filter input signal to indicate failure if this voltage developed across the sensor coil approaches either the upper or lower reference voltage.