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Project Notes

#432 ULN2003A Stepper Driver Modules

Investigating the common ULN2003A modules provided for unipolar stepper motor control - this one is identified as X113647

Build

Notes

Unipolar stepper motors are commonly used with microcontrollers. One the one hand they are simple to drive - no polarity reversal required. But on the other hand, the current/power requirements of the motors usually exceed the capability of the microcontroller (e.g. Arduino) board to supply directly.

The most common solution for this is to employ the ULN2003A Darlington transistor array chip. It can be dropped on a breadboard with no additional components in a moment, but it is also common to find ULN2003A modules offered with some additional features, such as:

  • LEDs for activity indication on each stepper coil connection
  • bypass capacitor on the motor power line

While ULN2003A modules can literally be used for any purpose, they are typically aimed at stepper motor use, as they connect up only 4 of the Darlinton pairs, and include a 5-pin connector commonly used with stepper motor drives.

The X113647 Driver Board

There are any number of versionss of the ULN2003A module. I have one identfiied as X113647 and is commonly supplied with the 28BYJ-48 stepper motor.

In addition to LEDs and a smotthing capacitor, this module includes a jumper that disconnects the positive motor supply from the connector to the motor - though I can’t think of a really good reason why this might be useful.

Build

When used with the 28BYJ-48, the connections are as follows:

Controller-side Stepper-side 28BYJ-48
IN1 OUT1 Blue
IN2 OUT2 Pink
IN3 OUT3 Yellow
IN4 OUT4 Orange
- COM: 5-12V Red
GND GND -

Construction

Breadboard

Schematic

Credits and References

About LEAP#432 StepperULN2003
Project Source on GitHub Return to the LEAP Catalog

This page is a web-friendly rendering of my project notes shared in the LEAP GitHub repository.

LEAP is my personal collection of electronics projects, usually involving an Arduino or other microprocessor in one way or another. Some are full-blown projects, while many are trivial breadboard experiments, intended to learn and explore something interesting (IMHO!).

The projects are usually inspired by things found wild on the net, or ideas from the sources such as:

Feel free to borrow liberally, and if you spot any issues do let me know. See the individual projects for credits where due. There are even now a few projects contributed by others - send your own over in a pull request if you would also like to add to this collection.