Unipolar vs. Bipolar drive for stepper motors, Part 1: principles - Power Electronic Tips
Controlling Bipolar Stepper Motors with the PIC16F84 schematic circuit - Controlling Bipolar Stepper Motors with the PIC16F84 schema and asm code - Schematic Circuits Elektropage.com
Art's Theremin Page: Bipolar Stepper Motor Control Circuit
Bipolar stepper motor drive circuit diagram under Stepper Motor Circuits -59667- : Next.gr