The present invention relates to a current multiplier primarily in the field of power conversion. The invention relates to a controlled current multiplier with a resonant winding to assist with, for example, power conversion. In particular, but not solely, the invention may broadly consist in a current multiplier comprising: a primary winding associated with a power source; a secondary winding associated with a load; a resonant winding associated with a capacitance; and a control means for controlling an output of the secondary winding to the load, the control means associated with the primary or resonant winding. This allows, for instance, control of the high current output to be placed on a low current winding.