Abstract: A detector circuit is to be used for measuring current by means of substantially identically wound ring core transformers, in which magnetomotive forces are induced by a main current. The magnetomotive forces are counteracted by magnetomotive forces induced by a compensating current. Two of the ring core transformers (2, 3) are magnetized in antiphase by means of a modulation signal. The detector circuit includes optionally a synchronous rectifier for providing an adjusting signal for the compensating current. According to the invention means are provided for compensating for possible differences between the two ring core transformers for the modulation signal. These means include a cornmon winding surrounding the two ring cores (2, 3), said common winding detecting a possible error signal used in a negative feedback loop which automatically seeks to establish an equilibrium.

Abstract: A detector circuit to be used for measuring current and including a main current transformer and two substantially identical auxiliary current transformers, where magnetomotive forces are induced by a main current, said magnetomotive forces being counteracted by magnetomotive forces induced by a compensating current (i4) in a compensating winding (L4) across at least two annular cores (2, 3) at the same time as the two auxiliary current transformers are magnetized in antiphase by means of a modulation signal, said circuit further including a synchronous rectifier for providing an adjustment signal for the compensating current (i4). According to the invention, the compensating winding (L4) is formed by a so-called “pilgrim winding”.

Abstract: The measurement of large DC and AC currents, are measured by a zero-flux current transformer. Two identically wound toroidal cores in which the magnetic flux induced by a primary current is neutralized by a counter-flux induced by a compensation current is passed through a compensation winding (14) common to both cores and having many turns. The compensation current is adjusted by means of an amplifier so that the mean flux in the cores is zero. The intensity of the compensation current is measured by the voltage drop across a measuring resistor.

Abstract: An apparatus for ion-implantation in elements, especially discs of semi-conducting material, in which a vacuum container has an end wall which has lock means by which the elements may be passed from the outside of the container to a position in the end wall, where one of its surfaces is exposed to the vacuum space in the container and treated by ions. The lock means includes a rotatable slide valve mounted between two parallel walls in one of which an aperture to the outer atmosphere is provided and in the second of which an aperture to the inner space of the container is provided. A number of apertures, corresponding to the said apertures in the walls, are provided in the slide value. The elements are positioned in one of the apertures in the slide valve, and by its rotation, conveyed to the wall aperture opening into the vacuum space. In the two parallel walls, two sets of cavities are provided, one encircling the other, each of which is connected to a separate vacuum source.