Abstract: A current controller for controlling an input current carried by a primary conductor. The current controller has a gapped core of magnetic material magnetically coupled to the primary conductor, as for example by the primary conductor being wound around the core. A secondary conductor is magnetically coupled to the core of magnetic material in an opposite manner to the primary conductor such that current flowing in the secondary conductor generates a second magnetic field in the core opposed to the first magnetic field. A Hall effect latch is located in the air gap and has output voltage corresponding to a hysteresis function of the difference in the first and second magnetic fields.