Abstract: The invention is directed to a circuit for processing a signal (UL) of a lambda probe having a probe signal terminal on which the signal (UL) is outputted and a probe ground terminal. The circuit includes a voltage source having a plus pole and having a minus pole connected to the probe ground terminal. A first network of passive components is connected between the plus pole and the probe signal terminal for dividing the voltage between the plus pole and the probe signal terminal in a pregiven ratio thereby providing a divided potential as a first analog signal. An analog-to-digital converter has an input and is connected to a chassis ground at a ground potential different than the ground potential at the probe ground terminal. A second network of passive components is connected to the plus pole for supplying a potential proportional to the potential on the plus pole as a second analog signal.

Abstract: In a circuit arrangement for operating a multiphase synchronous motor (10) on a direct current voltage main current valves (15-18), which are successively actuated via a ring counter (38), are connected in series with the phases (w.sub.1 -w.sub.4) of the armature winding (12) of the motor (10). A ring counter switching device (19) advances the ring counter (38) by pulses derived from the comparison of in voltages dropped across two blocked current valves (15-18). To restrict the self control range of the motor to an angular range which is much smaller than half a period, of the voltage drop decreasing in the course of time is additionally compared with a set voltage (k U.sub.S) by the ring counter switching device (19) and the ring counter advancement is enabled only for as long as this voltage drop is greater than the set voltage value.

Abstract: Commutation of the stator windings of a synchronous motor energized by a d.c. supply is controlled by comparison of voltages induced in two stator windings neither of which is a winding previously energized nor a winding about be energized. For speed control, turning on of the winding next energized can be delayed controllably. Motor current during start-up or overload can be limited by chopping, with a variable keying ratio, the d.c. supply connection to the motor during the first 80% of the period of energization of each stator winding. For reducing delay in starting, the rotor may be brought into a particular position automatically every time the motor is stopped or, in the case of a fuel pump motor for an injection type internal combustion engine, just before starting the engine through a supplementary contact controlled by the ignition key. Starting up can be provided by two initial pulses of commutation provided by means of an oscillator and two transistors.