Abstract: The present invention is related to a voltage conversion apparatus having a first loop circuit and a second loop circuit which share an inductance component, in which a current passes through the first and second loop circuits alternately in accordance with ON/OFF operation of a first switching element provided in the first loop circuit, characterized in that a direction of a magnetic field through the first loop circuit generated at the ON operation of the first switching element in the first loop circuit is the same as a direction of a magnetic field through the second loop circuit generated at the OFF operation of the first switching element in the first loop circuit subsequent to the ON operation.

Abstract: The present invention is related to a voltage conversion apparatus having a first loop circuit and a second loop circuit which share an inductance component, in which a current passes through the first and second loop circuits alternately in accordance with ON/OFF operation of a first switching element provided in the first loop circuit, characterized in that a direction of a magnetic field through the first loop circuit generated at the ON operation of the first switching element in the first loop circuit is the same as a direction of a magnetic field through the second loop circuit generated at the OFF operation of the first switching element in the first loop circuit subsequent to the ON operation.

Abstract: A vehicle speed determining device determines a running speed of a vehicle, on the basis of pulses received from a vehicle speed sensor. A first determination that the running speed of the vehicle has been zeroed is made, if a next pulse has not been received from the sensor, within a predetermined first length of time after the reception of a last pulse from the sensor. A second determination that a period of the next pulse to be received next is abnormally long is made, if said next pulse has not been received within a predetermined second length of time after the reception of the last pulse. If the second determination is made, the first determination is inhibited until the next pulse has been received.

Abstract: A diagnostic system for watching the sound operation of a kickdown switch in an automotive vehicle equipped with an automatic transmission adapted to be prohibited from operating at the highest speed stage according to the operation of the kickdown switch, the system including a comparator which compares an output signal from a throttle opening sensor corresponding to the depression of the accelerator pedal of the vehicle and an output signal from the kickdown switch, and generates a warning signal when the two output signals are not correlated with one another in a predetermined mutual relation so as to inform the driver of a malfunction of the kickdown switch.