Abstract: An analog angle encoder is provided having a resistor track and a wiper contact associated with the resistor track, a conductor track concentric with the resistor track, wherein one end of the resistor track is connected to ground and the other end is connected to an alternating voltage.

Abstract: A speed control method for controlling an electric motor by varying the supply duration of the motor, comprises the steps of:initially storing, for a constant speed to be obtained, the curve of the current in the motor as a function of the supply duration;selecting a supply duration;measuring the resulting current in the motor; andcorrecting the supply duration so that the point defined by the supply duration and the resulting measured current converges towards a point of the curve.

Abstract: A method for controlling a valve including a direct current motor acting upon an aperture adjusting part (3) against the force of elastic means (11) biasing the aperture adjusting part towards a zero flow rest position, comprising the steps of: selecting a desired valve aperture; determining a time interval (T.sub.a) as a function of the desired valve aperture; supplying the motor with a first constant current of a sufficient value for rotating the motor, during the mentioned time interval; supplying the motor with a second constant low value current thereafter until a next valve aperture is selected, this low value current being sufficient to hold the motor in its position against the force of the elastic means.