Abstract: The present invention provides spark plug that can improve detection accuracy of pre-ignition caused by flame kernel occurring inside spark plug. Terminal is located at a rear end side with respect to thread portion of metal shell. Detector electrode is provided at a portion located at a top end side with respect to a top end of contact portion between reduced diameter portion and shelf portion or packing in a space formed between outer periphery of insulator and inner periphery of the metal shell. The detector electrode and the terminal are connected by conductor. The detector electrode and the conductor are insulated from center electrode, the metal shell and ground electrode. Since the detector electrode is located in the space between the outer periphery of the insulator and the inner periphery of the metal shell, an early detection of the flame kernel occurring in this space can be possible.

Abstract: An illustrative example method of monitoring value added activity includes positioning a detector near a selected portion of a machine using a clip for situating the detector in a position where the detector can detect at least one electrical characteristic associated with operation of a machine; communicating an indication of the detected electrical characteristic between the detector and a user interface; and displaying a visual representation of value added activity information based the indication.

Abstract: An electronic device according to various embodiments includes: a housing; a plurality of metallic parts forming a portion of the housing; a clock generator disposed in the housing; and a processor is configured to sense a grip on the electronic device based on a current loop formed by a first signal generated by the clock generator and transmitted through a first metallic part and a second metallic part of the plurality of metallic parts, wherein the second metallic part is disposed adjacent to the first metallic part with a first separator disposed between the first metallic part and the second metallic part and configured to electrically separate the first metallic part and the second metallic part.

Abstract: An active electromagnetic interference (EMI) filter includes an amplifier configured to sense noise signals on a power conductor, and drive a cancellation signal onto the power conductor. The cancellation signal is to reduce the amplitude of the noise signals. Some embodiments of the active EMI filter include a high frequency compensation network that improves the high frequency phase margin of the active EMI filter and improves the stability of the active EMI filter at high frequencies. Some embodiments of the active EMI filter include a low frequency compensation capacitor that increases the phase margin of the active EMI filter at low frequencies. Some embodiments of the active EMI filter include low frequency compensation circuitry that increases the low frequency tolerance of the active EMI filter.

Abstract: The invention concerns an asset monitoring system (10) having a monitoring unit 8 and a plurality of sensors (4) onboard the asset. The sensors (4) are arranged to measure a plurality of operational variables for the asset in use and the monitoring unit (8) is arranged to receive operational variable measurements output from the sensors. The monitoring unit is also arranged to determine a current value of a sensor characteristic (ZA1; ZB1) for each sensor and to compare the current sensor characteristic value with a predetermined sensor characteristic value in order to determine automatically whether a change of one or more sensors has occurred between instances of operation.

Abstract: The disclosure relates to mitigating the effect of a sudden change in sensor calibration parameters. An embodiment of the disclosure retrieves a current calibration parameter value for the sensor, determines a new calibration parameter value for the sensor, and generates transitional calibration parameter values based at least on the current calibration parameter value and the new calibration parameter value using an interpolation function configured to prevent a sudden change in the sensor calibration parameter values.

Abstract: An induction cleaning analyzing system includes a pressure sensor, an ignition event detector, and a control module. The pressure sensor measures airflow pressures of intake air and/or exhaust from cylinders in a common airflow pathway of a vehicle. The ignition event detector determines ignition events of the cylinders. The control module obtains pressure waveforms representative of the airflow pressures and divides the pressure waveforms into waveform segments. The control module associates different subsets of the waveform segments with different ones of the cylinders using the ignition events. The control module also identifies cyclic variations in the airflow pressures flowing in the common airflow pathway and caused by at least one of the cylinders by examining the waveform segments associated with the at least one of the cylinders.

Abstract: The present invention provides an apparatus for automatic connection between an automobile diagnostic device and a VCI device and a method for the automatic connection. The method includes the steps of: periodically connecting the VCI device with at least one of a plurality of connection modes in pre-stored connection records when the automobile diagnostic device is started; and, when successfully connecting the VCI device with a successful connection mode, communicating with the VCI device with the successful connection mode. The method and apparatus according to this invention significantly improve the operation efficiency and user experience of the automobile diagnostic device.

Abstract: A self charging ion current sensing circuit is provided. The self charging ion current sensing circuit is coupled to spark generation circuitry, and utilizes the spark plug electrodes as the ion current sensing electrodes. The self charging is achieved by utilizing the spark current during an ignition event to charge an ion bias capacitor. After the ignition event, the charge voltage build up on the ion bias capacitor is used to provide an ion current across the spark plug gap. The ion current is passed through an offset stage that translates the ion current sense voltage to a voltage that can be buffered and amplified from a single power source available in automotive and vehicular applications. The output of the circuit provides tri-state information, including spark current, null current, and linear representation of ion sense current.

Abstract: An ion current detecting apparatus includes a capacitor C that is charged as a spark plug 3 discharges, a Zener diode ZD that limits a maximum voltage of the capacitor C while charging, a detection resistor R2 through which a discharge current of the capacitor C flows, and a comparator circuit 5 that compares a current value of the detection resistor R2 with a predetermined value. A charge quantity Q of the capacitor C at discharge start is set so that, as a consequence of a discharging operation of the capacitor C, discharge duration required until the current value of the detection resistor R2 falls below the predetermined value becomes longer than time duration in which the ion current generated by fuel combustion in the engine combustion chamber lasts. The ion current detecting apparatus automatically detects degradation in an insulation resistance in the spark plug, ensuring normal operation in engine control.

Abstract: A tamper resistant hourmeter is provided for an engine powered lawn mower. The hourmeter has a first pin connected to a positive voltage from a battery through a key actuated switch, a second pin to ground, a third pin to a magneto ignition, and a fourth pin to a fuel shutoff solenoid. The tamper resistant hourmeter connects the positive voltage from the battery to the fuel shutoff solenoid. The fuel shutoff solenoid opens a fuel line to the engine only if the key actuated switch is in either of the run or start positions.

Abstract: A system and method for non-contact engine parameter sensing. A magnetized engine component establishes a magnetic field that varies in response to stress imparted within the engine. A magnetic field sensing element spaced from the magnetized engine component is configured to provide an output indicative of a state of combustion in response to the magnetic field.

Abstract: A system for detecting spark in an igniter for a gas turbine engine. An igniter generates a plasma, or spark, somewhat similar to an automotive spark plug. In the invention, an inductive pick-up is positioned adjacent the igniter, to detect current pulses in the igniter, to thereby infer the presence of spark. The pick-up can take the form of a coil embedded in a mounting bracket which is used to fasten the igniter to the engine.

Abstract: An improved hand held starting/charging system tester. According to one aspect of the present invention, the portable handheld tester includes a connector to which various test cables can be removably connected to the tester. Detection circuitry within the tester determines which of several types of test cable is connected to the tester before testing. According to another aspect of the present invention, the portable handheld tester includes an improved user interface that permits a user to review test data from previously performed tests and further permits a user to either skip a previously performed test (thereby retaining the previously collected data for that test) or re-do the test (thereby collecting new data for that test). According to yet another aspect of the present invention, the portable handheld tester that performs a more complete set of tests of the starting/charging system.

Abstract: The present invention relates to an ignition coil tester having a control module and an output electronics for testing the functioning of rod-type ignition coils, which is connectible to a diagnostic tester, the rod-type ignition coil having a primary winding and a secondary winding for generating the ignition voltage as well as a field guide plate, a plug connector and a secondary output. To be able to perform a component test on a rod-type ignition coil uninstalled from an internal combustion engine, the present invention provides for the ignition coil tester to have a housing and a spark plug dome for receiving the rod-type ignition coil, the dimensions and shape of which essentially correspond to those of a spark plug dome in an internal combustion engine and/or are adjustable to the dimensions of the latter.

Abstract: A digital engine operating time measuring apparatus for an internal combustion engine. The apparatus is powered by a magneto of the engine and accumulates engine operating time only when the engine is operating. The apparatus includes power regulation circuitry including a pair of terminals coupled to the engine magneto. The power regulation circuitry converts a time varying electrical signal generated by the magneto when the engine is operating to a low voltage DC signal. The apparatus further includes digital circuitry coupled to an output of the power regulation circuitry for calculating accumulated engine operating time. The digital circuitry is powered by the low voltage DC signal of the power regulation circuitry and only accumulates engine operating time upon sensing the low voltage DC signal. The apparatus further includes a display coupled to the digital circuitry for displaying accumulated engine operating time as calculated by the digital circuitry.

Abstract: An ignition system into which signal lines and an evaluating circuit are integrated, so that the signals of a sensor integrated into a spark plug may be passed on, without additional mounting expenditure and space requirement, to a control unit of the engine control.

Abstract: A capacitive sensor for a coil-on plug ignition testing apparatus includes a first portion of the capacitive sensor and a second portion of the capacitive sensor, at least one of which has a substantially planar base, and each of which has one or more engagement members projecting downwardly therefrom. One of or both of the first portion and the second portion may be a capacitive element forming a part of the capacitive sensor. The second portion is connected, and is configured to slide relative, to the first portion. A biasing element is disposed between the first and second portions to bias the first portion toward the second portion and to maintain the first portion and second portion in a compressed state. The first portion may be translated relative to the second portion against a bias of the biasing element, to an extended state for securing to a coil-on plug housing.

Abstract: An ignition and diagnostic system (10) for an internal combustion engine includes a sparking device (12) through which a low voltage diagnostic device (54) monitors a sensing feature, for example spark gap (30) conditions, during spark intervals and returns diagnostic feedback to an engine control module (56). A coil (44) is electrically operatively connected to the sparking device (12) through a lead wire (48). The lead wire (48) can be removed and reinstalled with respect to the sparking device (12) via a flexor joint (60) for installation and maintenance. The flexor joint (60) enables positive electrical contact during operation so that low voltage signals from the diagnostic device (54) are maintained even during severe vibration conditions. The flexor joint (60) includes in one embodiment a compression spring (62) which is fully compressed or over-compressed.

Abstract: A variable reluctance sensor for use with an ignition timing device includes a support tube insertable in a bore extending from a first end to a second end. A sensor housing is insertable in the bore, while a variable reluctance probe is disposed in the sensor housing.

Abstract: An igniter for a gas turbine engine. An igniter generates a plasma, or spark, somewhat similar to an automotive spark plug. In the invention, an inductive pick-up is used to detect current which produces the spark, the thereby infer the presence of spark. Further, the sensor is located directly adjacent the igniter, in a hot environment, often exceeding 400 F.

Abstract: A capacitive sensor for an ignition testing apparatus includes a substrate bearing a sensor metallization and a ground metallization, an output lead, a mounting device integrated with the substrate and configured to permit the substrate to be releasably mounted to an ignition coil housing, and a sensor displacement assembly integrated with the substrate and/or the mounting device. The sensor displacement assembly includes at least one member configured to move at least a portion of the sensor metallization in a first direction toward an ignition coil housing and/or a second direction away from an ignition coil housing and/or a third direction lateral to the ignition coil housing while the substrate is mounted on an ignition coil housing using the mounting device.

Abstract: A variable compensation circuit for capacitive adapters is provided and includes an input connector for receiving a signal output from a capacitive adapter positioned within an electric near field emitted from a component of an engine ignition system, an output connector for outputting a signal output from the variable compensation circuit, a capacitive divider circuit portion disposed in series between the input and output connectors, the capacitive divider circuit portion comprising at least one of a variable capacitor and a plurality of fixed capacitors. The variable compensation circuit also includes a switching element configured to enable at least one of a selection and de-selection of the plurality of fixed capacitors and adjustment of a variable capacitor to provide one of a plurality of selected capacitance reactance ratios.

Abstract: Detecting the magnetic field generated by a coil-on-plug (101) (aka coil-over-plug) using an adjustable probe (111). The probe (111) includes a signal detector (115) for detecting the field, a detachable adapter (117) configured to detachably attach to the housing (107) of the ignition coil at a specified location (113), and an adjustable connector (119 and 121) that adjustably connects the signal detector to the detachable adapter in a first predetermined position or in a second predetermined position. A detecting process and a diagnostic system using the probe are also disclosed.

Abstract: A charge pump is used to supply current to the ionization detection circuit. To detect in-cylinder ions generated during the combustion process, a DC bias voltage needs to be applied. There are two ways to generate the DC bias: conventional DC power supply (large electronics) and capacitor charges by primary or secondary flyback voltage (high voltage capacitor). Typically, flyback voltage is used to charge the capacitor which supplies current to the ionization detection circuit. This necessitates the use of high voltage capacitors. Generally, ceramic capacitors are used. However, as temperature fluctuates, the board that the capacitor is mounted on can flex, causing the ceramic capacitor to crack. This invention proposes to use a high voltage charge pump to provide enough DC bias voltage for measuring ionization current. In a preferred embodiment, a model number M1C4827 EL driver is used in the charge pump circuit.

Abstract: The method and apparatus of the present invention are useful for the monitoring of the electrical signals within an internal combustion spark plug circuit and the killing of a spark plug within that circuit. The invention essentially consists of connecting a transformer to the high voltage side of the spark plug circuit. Through the use of impedance and inductance, the present invention can either produce a low voltage replica of the waveform of the high voltage electrical signal which is directed to a spark plug or can effectively prohibit that spark plug from firing by short circuiting the low voltage side of the transformer of the device.

Abstract: An inspection object constructed of an ignition plug and an ignition coil is inserted in an inspection housing that does not have a ground electrode. A voltage generated in the ignition coil is measured while the inspection object is housed in the inspection housing. Electrical discharge does not occur because the ground electrode is not provided. Therefore, the voltage generated in the ignition coil is properly measured for quality inspection of the ignition coil.

Abstract: A capacitive probe for simultaneously detecting a plurality of electric near fields present proximate a hybrid or DIS ignition under test during operation of the hybrid ignition, the hybrid or DIS ignition having a first output to a first spark plug and a second output to a second spark plug. The probe includes a base configured for removable attachment to an ignition housing by means of an interference fit and a single capacitive sensor fixed to the base. The sensor is disposed on the base and has an electrical lead connected thereto.

Abstract: A diagnostic system for analyzing the operation of an engine is provided including a capacitive probe for simultaneously detecting an amplitude of a first and a second electric near field present proximate a hybrid or DIS ignition coil housing. The capacitive probe includes a fastening device configured to removably attach the capacitive probe to the ignition coil housing and a body bearing a first signal detector and a second signal detector. Each of the first signal detector and a second signal detector are arranged adjacent a location of a respective one of the first and second electric near fields for detecting an amplitude of the respective electric near field. Each signal detector outputs a signal representative of a respective electric near field.

Abstract: A distributorless ignition adapter for diagnostic oscilloscopes which an interface box, an oscilloscope connection cord and several inductive pick ups. The oscilloscope connection cord has a first end connected to the interface box and a second end terminating in an oscilloscope plug. The several inductive pick ups are connected to the interface box, whereby passage of electrical current through ignition coils is sensed and data relating to properties of the electrical current is transmitted to an oscilloscope via the interface box and the oscilloscope connection cord. Preferably, each of the several inductive pick ups is sufficiently flexible to wrap around an ignition coil. This enables the inductive pick ups to be adapted to different sizes of ignition coil. Preferably, each of the several inductive pick ups is detachably secured to the interface box. This enables a technician to alter the number of inductive pick ups to correspond with the number of ignition coils for a particular model of engine.

Abstract: A data acquisition module for collecting data from engine-driven power equipment. The module records the operational characteristics of the power equipment. The module stores historical operational data such as time of use, total operational time, load, speed, etc. The module also provides information to the user when service or maintenance is due to be performed.

Abstract: Method and apparatus for displaying ignition coil waveforms. The method includes disposing a plurality of capacitive elements adjacent a plurality of coil-over-plug ignition coils. Signals detected by the capacitive elements are supplied to an adapter in which signal gain, polarity, and range are selected according to a particular vehicle tested, and displayed.

Abstract: A low cost, easy to use, hand held pulse stream analyzer is designed to show, after an engine stops operating, which pulse stream, ignition or injection, quit first. Additionally, the analyzer is capable, using relative time domain analysis to comparatively analyze these pulse streams to the alternator ripple pulse stream, of determining if the fuel flow to the injectors quit, thus causing the engine to quit. This information quickly gives the technician a direction to investigate to find a responsible faulty component for the problem being experienced, and is especially helpful in attempting to diagnose intermittent faults in a much more efficient manner. The inventive device is usable on virtually all brands and types of gasoline powered vehicles.

Abstract: An engine analyzer senses and displays secondary ignition signals from a DIS engine using a two sets of test leads. The engine analyzer receives the secondary signals from both sets of leads and produces positive and negative peak values for each set of leads during each cylinder firing. Based upon the positive and negative peak values for both sets of leads, during each of the cylinder firings, the engine analyzer selects which lead set and which polarity will be used to supply the secondary voltage signal for each cylinder to be digitized and displayed.

Abstract: A motorcycle including a two-cylinder engine. The engine includes a housing, first and second cylinders having first and second combustion chambers, respectively, and first and second pistons reciprocating in the first and second chambers, respectively. The motorcycle further includes a spark generating circuit including a spark plug having a spark gap exposed to the first combustion chamber, an ion sensing circuit including the spark plug and being operable to generate an ion signal indicative of an ion current generated across the spark gap, and an analysis module coupled to the ion signal circuit. The analysis module is operable to receive the ion signal and to analyze the ion signal to determine whether a no-combustion event occurs in the first cylinder. The analysis module may be further operable to determine if the spark generating circuit has an intermittent connection.

Abstract: A motor test fixture for connection to motor terminal lugs. The fixture includes a housing including a plurality of external apertures positioned and formed to enclose the motor terminal lugs; an aperture in the housing; a chamber within the housing having a first end open to the aperture; and a slide bar moveably located in the chamber and moveable between at least a first position and a second position. The fixture also includes a plurality of plates moveably mounted in the housing to move between a motor lug engagement position and a motor lug disengagement position; and a plurality of plate motivators. Each plate motivator is arranged on the slide bar to engage a respective one of the plates and, when the slide bar is in the first position, to motivate the respective plate to the lug disengagement position and, when the bar is in the second position, to motivate the respective plate to the lug engagement position. The motor test fixture also preferably includes a polarity bar.

Abstract: A spark plug cap for facilitating the fitting/detaching operation of a spark plug with a built-in pressure sensor, and a method of easily fitting the spark plug with a built-in pressure sensor are provided. The spark plug cap is provided with a cylindrical part of glass-containing PBT, a grommet provided with a cable passing groove, and an ignition coil unit provided with a high voltage terminal. The cylindrical part includes a first engagement part engageable with a spark plug fastening tool on one end, a second engagement part of a metal material engageable with a hexagonal part of the spark plug with a built-in pressure sensor on the other hand, and a groove-shaped clamp part on the outer side surface. By engaging the hexagonal part with the second engagement part to attach the cylindrical part to the spark plug, holding a sensor output cable by the clamp part, and fitting and fastening the spark plug fastening tool in the first engagement part, the spark plug is fitted into an internal combustion engine.

Abstract: A coil-on plug testing apparatus for detecting a weak field output by a shielded coil-on plug ignition and generating an output signal representing an ignition signal includes a capacitive sensor attachable to a coil-on-plug device for detecting an electric field generated by the shielded coil-on plug device during a firing event and generating and outputting a voltage in response thereto. A signal processing circuit electrically coupled to the capacitive sensor is configured to generate an output signal in response to variations in the voltage output by the capacitive sensor in response to a detected electric field. The signal processing circuit comprises an amplifier configured to amplify an output voltage of the capacitive sensor.

Abstract: A diagnostic test system having a portable testing device for motor vehicles, controllers having an on-board diagnostic device being provided which control and monitor the engine control system and other systems of the vehicle, generate and store error codes, and which can be connected to an external testing device via a motor vehicle-side diagnosis/test plug. The external portable testing device is equipped with a modem and connected to a mobile telephone, a hand-held cell phone in particular, in order to perform error diagnosis and troubleshooting in such an interconnected network outside stationary repair shops.

Abstract: A tachometer apparatus of a remote vehicle starting system for providing tachometric information. The apparatus includes an antenna disposed proximate to the engine compartment of the vehicle and adapted to pick up an RF signal generated by the firing of the spark plugs in the engine compartment. The apparatus also includes an RF detector having the antenna coupled to the input thereof and providing at its output a tachometer signal for coupling to a controller and providing a signal indicative of the running status of the vehicle engine and of the tach speed of the engine.

Abstract: An ignition timing device for timing an engine having a timing port includes a sensor securable in the timing port to provide a timing mark signal. An ignition sensor is adapted to provide an ignition signal. A comparator receives the timing mark signal and the ignition signal. The comparator provides an output signal indicative of substantial simultaneous occurrence of timing mark signal and the ignition signal. An indicator receives the output signal and is operable as a function thereof.

Abstract: A tachometer apparatus of a remote vehicle starting system for providing tachometric information. The apparatus includes an antenna disposed proximate to the engine compartment of the vehicle and adapted to pick up an RF signal generated by the firing of the spark plugs in the engine compartment. The apparatus also includes an RF detector having the antenna coupled to the input thereof and providing at its output a tachometer signal for coupling to a controller and providing a signal indicative of the running status of the vehicle engine and of the tach speed of the engine.

Abstract: A hand-held ignition voltage tester for detecting voltage on a spark plug wire in an ignition system, such as a distributorless ignition system. The tester includes a housing, positive and negative power cables and a capacitive probe for capacitively coupling to the spark plug wire. The capacitive probe generates a voltage signal which is representative of the voltage on the spark plug wire. A plurality of voltage level indicators are mounted to the housing to form a bar graph, with each indicator corresponding to a selected voltage level. A measurement circuit is coupled to the power cables and the capacitive probe for activating the voltage level indicators in response to the voltage signal.

Abstract: An apparatus for measuring ignition charge signals produced by coils of coil-on-plug devices of an internal combustion engine. A signal detector comprises an insulating substrate having a first conductive planar layer on a first side and a second conductive planar layer on a second side. The first layer is coupled to a signal wire and the second layer is coupled to a ground wire. When the signal detector is held in close proximity to the coil of the coil-on-plug, ignition signals generated by the coil and passing to the plug are detected. The detected signals may be coupled to a signal analyzer for display and analysis. The amplitude of the signal that is output by the signal detector may be adjusted to different coils having different output signal strengths by modifying the ratio of the surface areas of the first layer and the second layer.

Abstract: A method for surveying the operating conditions of an internal combustion engine with spark ignition, wherein in one and the same engine cycle a plurality of primary charging cycle are generated which produce corresponding secondary discharge cycles. The pressure pattern in the combustion chamber is determined, in each period of time, as the product of the maximum intensity of the induced primary voltage (V1i) by the respective duration (ti).

Abstract: The present invention is an assembly line testing apparatus and method for automatically determining whether a size of a gap, within at least one component of an article of manufacture, is within an acceptable range, during assembly of the article of manufacture. The present invention uses a microcontroller to control the operation of the assembly line testing apparatus of the present invention such that the size of the gap may be checked in a flexible and reliable manner by repeating the cycle of checking for the size of the gap. The present invention may be used to particular advantage for checking that the size of a spark plug gap within a vehicle engine is within an acceptable range during assembly of the vehicle engine.

Abstract: A glow sensor which combines functions of a diesel engine glow plug with an ion sensor for sensing engine combustion initiation and characteristics includes a ceramic rod retained in a supporting ceramic sleeve carried by a metal shell mountable in an engine cylinder head. The ceramic rod includes a heating element in a glow tip at the inner end of the rod which, in use, extends into an engine combustion chamber or pre-chamber. A conductive material such as platinum or palladium is coated on the lower end of the glow tip and connected by a conductor with a source of electric voltage. In use, the voltage produces a current carried by electrons generated by ionization of the combustion chamber gases during combustion. The current varies with the degree of ionization and the amount of electrons generated during various phases of the combustion event. The resulting information is usable in controlling engine operation or evaluating its operation for test purposes.

Abstract: A device for detecting knocking in an internal combustion engine capable of preventing accuracy for detecting knocking from being deteriorated by noise when resetting the LC resonance masking unit. An ionic current signal detected by an ionic current detecting unit is supplied to a buffer amplifier 5 via an LC resonance masking unit 31. To a first operational amplifier 51 of the buffer amplifier is connected a capacitor 513 for rejecting noise in parallel with a first feedback resistor 512. A second operational amplifier inverts again the ionic current signal inverted by the first operational amplifier. The buffer amplifier prevents a stepwise change on the input to the band-pass filtering unit when the masking of the LC resonance masking unit is reset, and suppresses a reduction in accuracy for detecting the knocking.

Abstract: An informational/positional guide, which is disposable in an aircraft instrumentation interface, used with at least one mechanical guide key configured to guide interface engagement, and the guide key having an orientation specific to a particular type of aircraft equipment configuration, the guide is provided with a key engagement member. The key engagement member is formed to engage the guide key and is disposable in a variety of angular orientations to facilitate engagement with the guide key. The key engagement member is further provided with an aircraft equipment configuration sensor for identifying the aircraft equipment configuration type in response to sensed orientation of the key engagement member and for generating an electronic signal in response to the identification of the orientation of the key engagement member.

Abstract: A circuit arrangement measures an ion current generated in the combustion chamber of an internal combustion engine during an iron current flow phase following an ignition phase. A voltage drop across a feedback resistor (R.sub.1) connected in parallel to an inverting amplifier is measured since the voltage drop is proportional to the ion current resistance. The amplifier is connected with its inverting input to a low voltage end of a secondary winding of an ignition transformer or coil. The high voltage end of the secondary winding is connected through a spark gap of a spark plug to ground, whereby the spark plug functions as an ion current sensor during the ion current flow phase. Negative voltage peaks flowing during an ignition phase and the ignition current flowing during the ignition phase are diverted through respective first and second circuit branches. The first branch has a first semiconductor diode (D.sub.