The L293D is a Quadruple half H-Bridge IC, meaning that it has two H-Bridges used to drive motors in both directions. In this example we use each of the H-Bridges to drive a phase in the stepper motor while the Arduino and the stepper.h library control the order in which the phases will fire up.
Below you will find the circuit schematics and list of parts for this setup, and also a video showing how to build the circuit on breadboard.
1 x Arduino Board (or ATmega you can program)
1 x L293D IC (Datasheet: Download)
4 x 1KΩ Resistor R1 - R4
2 x 10uF 63V C1, C2
4 x 1uF 35V (Tantal) C3 - C6
1 x 1N4005 D1
1 x Stepper motor
1 x Heat sink (This is important If you plan to run the circuit for more than a few seconds/minuets, as the L293D drives a nice load which can cause it to get hot very fast. It does have thermal protection shutoff but you want to prevent the over heating in advanced)
Arduino source: Download
Breadboard layout: N/A