Abstract: A semiconductor device has a first-conduction-type semiconductor substrate (19), an internal circuit including a vertical bipolar transistor (18) formed in a second-conduction-type semiconductor layer (20), and a protective element (14). The protective element comprises a first-conduction-type diffusion layer (22a) formed at an upper part of a second-conduction-type semiconductor layer (20a) disposed on the semiconductor substrate (19), and a second-conduction-type diffusion layer (27, 30) formed in the first-conduction-type diffusion layer (22a). The diffusion layer (27, 30) is at least partly deeper than an emitter diffusion layer (23) of the vertical bipolar transistor (18).

Abstract: A metal detector comprises a detection coil disposed in a magnetic field, the ends of the coil being connected through a balanced resistor network to the inputs of a differential amplifier. A test signal is injected into the metal detector at a point such that the coil is effectively in series with one branch of the balanced resistor network. The injected signal produces a potential difference at the inputs of the differential amplifier, the magnitude of the potential difference being dependent on the resistance of the detection coil. The test signal is generated by a circuit including a microcomputer which successively feeds digital values corresponding to the sine function to a digital-to-analog converter, so that the converter generates the test signal in the form of a sine wave. The output signal from the differential amplifier is applied to an analog-to-digital converter.

Abstract: A monitor current to a squib as an air bag actuating element conducts in one and the opposite directions alternately. Each produced voltage value is differentially amplified with a positive reference voltage and a difference between the amplified voltages are calculated. Thus, an offset voltage of an operational amplifier used for the differential amplification is cancelled, and the difference between the two detected voltages becomes a voltage value which will be produced by a monitor current twice as large in current level. Thus, the squib is diagnosed accurately.

Abstract: A circuit arrangement includes a wear detector which is proportioned or which operates so that it wears (i.e., fails) faster than the other parts of the circuit arrangement. The wear detector may be made to wear faster than other parts of the circuit by being more heavily loaded during operation, by being configured to be more heavily stressed during operation, or by being subjected to more severe operating conditions. An indicator is connected to the wear detector so that, when the wear detector ceases to function, the indicator signals that the circuit arrangement is near the end of its useful life and is to be replaced.

Abstract: A component detector circuit operates to detect the presence or absence of a circuit component, such as an external component. A resistor detecting circuit includes a biasing circuit connected to the resistor. The biasing circuit generating a bias current. The resistor detecting circuit also includes a bias current threshold detector connected to the biasing circuit and a circuit connected to the bias current threshold detector which generates a signal indicative that the bias current is lower than threshold. A capacitor detecting circuit includes a circuit connected to a resistor and configured to be connected to a capacitor which establishes a time constant proportional to an RC product of the resistor and capacitor.

Abstract: A test circuit for testing a current-voltage conversion amplifier having photodiode (PD) without actually exposing light to PD, including a current mirror circuit having a first NPN transistor and a second NPN transistor, an input terminal for applying a test voltage, a resistor connected between the input terminal and a collector of the first NPN transistor, and a current terminal connected to a collector of the second NPN transistor. The test circuit passes a current from the current-voltage conversion amplifier to the current terminal according to the test voltage which is applied to the input terminal.

Abstract: A system for testing the integrity of critical circuitry, lines and wires employs a differential amplifier having an input resistance R.sub.in and a feedback loop with a resistance R.sub.fb. The critical wires being tested must be a signal wire series connected to a resistance R.sub.S, which is in turn series connected to a return wire. A test voltage source is connected to the noninverting input of the differential amplifier. The signal wire is connected to the inverting input of the differential amplifier. The test voltage source is activated by a test control unit. When activated, the test voltage source provides two distinct outputs allowing computation of a test gain in the presence of other functional signals. The test control unit measures the output V.sub.out of the differential amplifier and computes the value of the test gain. A break in either the signal wire or the return wire will result in a test gain of 1. If the signal and return wires are shorted, the test gain will be 1+R.sub.fb /R.sub.in.

Abstract: A test lead set for a four-terminal ohmmeter comprises separate conductor pairs with one conductor of each pair connected to a source while the other conductor of the same pair is connected to a meter. The conductor pairs, which are received within separate insulating shrouds, are provided at their remote ends with bifurcated clips having jaws for making individual connections between the conductor leads and a terminal of a device under test. The test lead set is coupled to the measuring instrument by banana-type plugs having separated conductive portions for engaging contacts within instrument receptacles so that separate connections to the source and measuring device can be maintained. The instrument receptacles are backwards compatible with a conventional, two-terminal, test lead set.

Abstract: An improved open circuit detector for testing a thermocouple for an open circuit condition. The detector includes a generator for providing and sourcing a tone signal to the thermocouple, wherein the tone signal has a known frequency and amplitude. A monitor analyzes the amplitude of a particular frequency component of a tone signal across the thermocouple. If the amplitude of the particular frequency component exceeds a predetermined threshold, an output is provided for indicating an open circuit condition for the thermocouple.

Abstract: The invention relates to a method and an arrangement for monitoring the operability of a heater of an oxygen-measuring probe which is mounted in the exhaust-gas channel of an internal combustion engine. The principle of operation of the invention is based on the fact that the supply voltage of the probe heater drops during loading by the electrical resistance of the heating element. The voltage difference is dependent upon the magnitude of the resistance and therefore at least the three states can be distinguished, namely: normal operation, circuit interruption and short circuit. The operational state of the probe heater which is so determined is displayed to the driver by activation of a corresponding control unit and/or is stored, as required, in a fault memory. The arrangement according to the invention can be realized by a computer or in a compact configuration and is suitable for use in a central control apparatus.

Abstract: The monitoring circuit for a sensor connected to a low-potential and high-potential line, such as a thermal element, includes a high-resistance pulldown resistor connected between the high potential line and ground, a offset voltage source connected to the low-potential line to supply an offset voltage higher than a minimum transistor control voltage; first and second testing transistor shaving control electrodes connected to respective ones of the lines via resistor arrangements; and a third testing transistor having a control electrode connected to an output of a p-type channel FET having a control electrode connected to one of the two sensor lines. Whether the operating state of the sensor is normal, involves a short circuit to ground or the supply voltage or an interruption of the sensor lines is determined by monitoring the switching states of the first testing transistor and a series combination of the second and third testing transistor.

Abstract: An electrical resistance and insulation tester providing a 12 volt D.C. and a 500 volt D.C. testing circuit. Indicating means are comprised of an incandescent bulb for the 12 volt D.C. test circuit and a neon bulb for the 500 volt D.C. test circuit. A 12 volt D.C. power input circuit and a 110 volt A.C. power input circuit provide for operation at either input. The tester also comprises a chargeable capacitor circuit that allows for testing when the instrument is not connected to any power input source.

Abstract: A checking circuit for checking the normal operation of a sensor comprising a sensor, a controller for switching the checking circuit operation between an open check mode and a sensing mode. The circuit for effecting the open check mode is responsive to a first logical output signal from the controller. The circuit for effecting the sensing mode is responsive to a second logical output signal from the controller, however, the sensing is only accomplished after successful completion of the open check mode.

Abstract: A detection circuit for detecting the existence of non-collapsing bubbles in the ink cells of a thermal inkjet printhead is connected to a heater element of an ink containing cell. The detection circuit has a sensing element of low resistance when compared to the resistance of the heater element so that printing and detecting operations can proceed simultaneously. Current in the heater element is proportional to the potential drop across the sensing element. An amplifier is used to measure the potential drop and is connected to a blocking capacitor. Non-collapsing bubbles are detected if the voltage drop across the sensing element varies from a reference level.

Abstract: According to the present invention, a method and device for detecting failure of heating elements in various jets of a thermal jet printing device is provided. The printing device which includes a plurality of thermally actuated printing jets, each of which jets includes a resistance heating element, is actuated when a current is supplied to generate a bubble. The bubble expands eject a drop of ink. Electrical circuit means are provided including power supply means to supply current to the electrical resistance elements. Control means are also provided to selectively connect the elecrical resistance elements to this power supply in preselected arrays for forming bubbles in selected configuration to perform the ink jet printing. The operation includes a test circuit coupled to the resistive heater elements and operable by the control circuit to generate a failure signal representative of a resistance above a preselected value in any resistance heating elements.

Abstract: A device is described for determining and/or controlling the operating data of automotive vehicles, particularly for controlling the velocity of vehicles with internal combustion engines and electric transmission of the position of the gas pedal to an electric setting element which is connected to the throttle valve or the displacement device of the injection pump, the device having a measuring device for determining shunt resistances to the electric position transmitter which is connected to the gas pedal and the throttle valve. Such shunt resistances (leak resistances) detrimentally affect the desired precise relationship of the position of the gas pedal to the position of the throttle valve.

Abstract: A condition monitoring system for a position sensor coupled to a control device in a throttle control system. The position sensor includes a potentiometer having a main resistor coupled across a source of electrical power and a wiper arm mechanically coupled to the control device and electrically coupled to the main resistor. An electrical signal is developed on the wiper arm which is directly proportional to the actual position of the control device. A sensing or monitoring resistor is connected in series between the main resistor and source of electrical power for providing a current measurement directly correlated with actual resistance of the main resistor. The voltage drop across the sense resistor is compared to a predetermined range for providing an indication of main resistor operation independently of wiper arm position.

Abstract: A method of diagnosing the deterioration of a zinc oxide type lighting arrester having one or more series-connected non-linear resistance elements including steps of elimination of the effects of capacitive currents from phase currents; obtaining a synthesized waveform using a window type transformer based on the resistance elements alone; and diagnosing the presence of a deteriorated non-linear resistance element by generating a first pulse voltage when the maximum crest value of the synthesized waveforms exceeds a predetermined value, generating a second pulse voltage representative of terminal voltage of the resistance element, and calculating the difference between the first and second pulse voltages.

Abstract: Load resistors connected in parallel in a heating circuit having switches operable to connect and disconnect the resistors from a common supply line for heating a plurality of zones to maintain predetermined temperatures therein, are tested by disconnecting all of the load resistors from the supply line to begin a testing operation. Any current conducted when all load resistors are disconnected from the supply line is measured, after which the load resistors are then individually and successively reconnected to the supply line. The current then conducted from the supply line in succession to the load resistors is measured and compared with reference values of current through the load resistors when functioning properly.

Abstract: An electric testing system to be attached to a water heater to permit instantaneous testing of the operability of each heating element comprising a separate branch circuit including each heating element and a current flow detecting device.

Abstract: For evaluating the condition of a first lightning arrester of the gapless metal-oxide varistor type that is connected across the high voltage winding of a transformer, I connect externally of the transformer a second arrester of the same type, but with means for selectively changing its breakdown voltage between a first value that is higher than the normal breakdown voltage of the first arrester and a second value that is lower than said normal breakdown voltage. Pulses are applied to the low voltage winding of the transformer while the second arrester has its breakdown voltage set at the first value and while said breakdown voltage is set at said second value. By determining whether or not the second arrester conducts in response to each of these pulses, it can be established whether the first arrester is then undamaged, damaged in a shorted mode, or damaged in an open mode.

Abstract: An apparatus for testing passive two terminal devices in the VHF range comprises an electrical signal generator whose frequency is variable over the VHF range, a distributed constant line having a first end connected to the generator and a second end connected to the device to be tested. A resistive .pi. network is connected to the first end of the line to measure directly the values of the incident wave and of the reflected wave or the maxima and the minima of the total wave at the first end of the line are detected, so as to determine the coefficient of reflection of the line connected to the device to be tested.