PLATFORM STEPPER MOTOR DRIVE

Here is the latest and smoothest stepper motor driver circuit . This was built from a design by Nils Olof Carlin and the full circuit diagram can be found on his web-page here. A full explanation of the operation will be found on that page, together with a pcb layout and waveforms by David Bevel. Note - my first motor ran off 3 volts and so Nils Olof kindly modified his circuit accordingly. My board layout and the component values below are only for this modification. The motor circuit required 3 v at ca. 600 mA , obtained via a L200 variable voltage regulator from the 12 volt supply. I've subsequently changed to a 12 volt motor and reverted to Nils Olof's unmodified circuit.

My build in its box. Note the rewind preset potentiometer at bottom and the battery state LED at the top centre.

Here is my pcb layout and the accompanying component placement diagram. This is a crude attempt - there are far too many wire links (shown in green) on the board !. I drew it onto the copper clad board using rub-down tranfers for the I.C. pads and a p.c.b. marker pen for the tracks. The diagrams are best saved, then scaled and viewed in a graphics program like Paintshop Pro as some of the lines are indistinct here.