Abstract: In a method and apparatus for transmitting signals from a control device to a diagnostic device in a motor vehicle, a transmission of signals in a serial form is obtained by means of an electric current. In order to detect whether the diagnostic device is connected to the control device a voltage is measured in a diagnostic signal-conducting lead connected to the diagnostic device. This voltage is varied by means of a resistor mounted at the input of the diagnostic device when the diagnostic device is connected to the control device.

Abstract: An internal combustion engine ignition system includes an output switching transistor (7), the emitter-collector path of which is in series with the primary winding (5) of an ignition coil (6). To attain a constant amount of ignition energy in the ignition coil (6), the control current for the base of the output switching transistor (7) is supplied by a constant-current source (9), the level of the constant control current being selected such that while the ignition energy is being stored in the ignition coil (6), the saturated operation of the output switching transistor (7) is maintained.

Abstract: A device is proposed for generating specific electrical voltage values for consumers associated with an internal combustion engine. The device also encompasses a voltage elevating circuit which can be switched on in the vicinity of the minimum voltages for the consumers. This means that this voltage elevating circuit does not need to be switched on continuously during engine operation, but rather only at times of increased power needs. The voltage elevating circuit has a series circuit of a coil 20 and a diode 21 in a voltage supply line, and the connecting point of these two components is briefly closed off from the other supply line in a clocked manner. The activation of the voltage elevating circuit can be switched on and off in accordance with the input and output voltages and in accordance with the maximum permissible switching current. Depending on the clock frequency of the switch 23, the line inductance of the supply line suffices as an inductance 20.

Abstract: A method and apparatus for use with fuel mixture preparation systems which employ an oxygen sensor in the exhaust line to determine the composition of the combustible mixture supplied to the engine and which adjust the mixture on the basis of the bi-valued signals from the sensor. In order to permit the use of these signals at lower than normal operating temperatures, where the internal resistance of the sensor is high and the output signal is skewed, the invention proposes generating a correction current which is passed through the sensor and which causes a voltage drop which symmetrizes the output voltage so that the two branches of the output signal always lie respectively above and below a fixed set-point voltage, thus permitting control loop processing.A circuit is also described which supplies the correcting current by comparison of the DC level of the output signal with the set-point value in a secondary feedback loop.

Abstract: The fuel supply control pulses of an internal combustion engine may be shortened or lengthened to provide operation of the engine at a definite fuel-air ratio. When operation takes place in a leaned-out region, the engine suffers dynamic instability, resulting in rapid fluctuations of the rotational crankshaft velocity, superimposed on regular, periodic changes due to compression changes.The maximum and minimum crankshaft speeds are measured at two different locations of the angular path by passing markers in front of an inductive transducer. The output signals from this transducer are fed to a gating circuit which controls the counting modes of a digital counter which is also supplied with a clocking pulse train at a constant, high frequency. The gating circuit causes alternate upward and downward counting in the counter so that a net difference of counted pulses is formed after each two successive counting periods.

Abstract: To accurately determine the position of a marker on a rotating disk, for example coupled to the crankshaft of an automotive engine to determine the angular position thereof, an inductive transducer picks up the field generated by a permanent magnet located on the disk and, to compensate for amplitude variations in the output due to speed changes of the disk, and eliminate the effects of spurious side lobes generated by reversely positioned magnets, the amplitude of the output signal is normalized in an amplifier which includes a non-linear input circuit. The non-linear input circuit, preferably, is a diode-resistor network, in which the diode is forwardly poled, and a controlled current is supplied to the diode, the control being effected by the output of the amplifier in a feedback circuit, so that the output obtained from the amplifier will be uniform regardless of change in speed of the rotating body, and hence change in amplitude of the voltage induced in the inductive pick-up.