Abstract: A converter is provided for stepping-down a DC power input to produce a DC power output of lower voltage. The converter includes a regulating unit (3), and, in series with it, an input resistor (4). In use, the resistor (4) is separated from the regulating unit (3) and is mounted on a body of a piece of machinery, so that heat produced within the resistor is transmitted to that machinery, and does not interfere with the operation of the regulating unit (3). The regulating unit (3) employs a linear conversion circuit which produces a stable (DC) output but, unlike conventional DC-DC converters, generates substantially no stray electromagnetic fields.