A dot wire driving apparatus for a printer which has a stabilised power source (3) including a smoothing coil (PL) and a smoothing capacitor (C1) for energising a driving coil (Li) for driving a dot wire (14) so as to form a dot on a printing medium, comprises a capacitor (C2) for storing electro-magnetic energy accumulated in the driving coil (Li) when current supplied thereto is terminated. A feedback loop (20, 22) feeds energy from the capacitor (C2) to the smoothing capacitor (C1) when the voltage of the former reaches a pre-determined level. Control circuitry (23, RD) maintains the voltage of the capacitor (C2) so that its voltage does not fall below the pre-determined level.
