Abstract: To control the current through a winding interconnected in an H-bridge to control e.g. a stepping motor, at the beginning of each chopper period, the H-bridge is kept in its slow demagnetization state during predetermined interval (t1-t2). Then, just before, at or just after the end of that interval, the actual current value (IA) is compared with a desired value (ID). If the actual value (IA) is smaller, the H-bridge is kept in its magnetization state, at the most until the end of the chopper period. If the actual value is larger, the H-bridge is kept in its fast demagnetization state, at the most until the end of the chopper period. Hereby, the current is regulated to the desired value with a minimum of current ripple. This reduces the electromagnetic radiation. Also, the impact of current spikes, appearing when the H-bridge is switched, is brought to a minimum.

Abstract: A magnetoelastic torque transducer for measuring, in a non-contacting manner, the torque in a stationary or a rotating shaft. The transducer comprises a shaft (1) with surrounding excitation windings (2, 3) and measuring windings (10, 11). Concentrically with the windings, anisotropic measuring zones are created by applying layers (8, 9), for example in the form of copper strips, on the surface of the shaft. The angle between the strips and a generatrix to the cylinder surface of the transducer shaft is in a preferred embodiment chosen to be .+-.45.degree. (FIG. 5).