Unipolar Stepper Motor Driver

  This page features a Unipolar Stepper Motor driver that uses an EDE1200, Unipolar, Stepper Motor Controller IC produced by eLab Digital Engineering.

  Five stepper motor control functions are provided: Step, Half-stepping, Direction, Free running and Outputs disabled.

  The circuit uses a ULN2803 darlington driver as its output device that can drive motors drawing up to 1.0 amperes per phase.

A printed circuitboard and parts are available for this circuit.


  If you are interested in printed circuit boards please send an email to the following address: rpaisley4@cogeco.ca Subject: EDE1200 Unipolar Stepper Driver - ULN2803

EDE1200 - Unipolar Stepper Driver PCB Schematic

Devices Used For This Circuit

  It is not the purpose of this page to provide full explanations of how these devices work. Detailed explanations can be found through datatsheets that are available from many source on the internet and from suppliers.

EDE1200 - Unipolar Stepper Driver Controller Inputs

  This EDE1200 Stepper Motor Controller circuit has the following control inputs and modes of operation:

  1. DISABLE MOTOR DRIVERS - When the DISABLE MOTOR DRIVERS input (Pin 6) is LOW, the four coil driver outputs of the EDE1200 are switched OFF and the the motor can be turned freely, regardless of the other input states.

  2. STEP INPUT - Each time the STEP input (Pin 9) goes LOW, the motor will move one step, depending on how the other four inputs are set.

  3. HALF STEP MODE - When the HALF STEP input (Pin 10) is LOW, the motor will move in Half Steps.

  4. DIRECTION - The DIRECTION input (Pin 7) controls the motor's direction of rotation depending on the input level (HIGH or LOW). The motor's true direction of rotation depends on order that the motor's coils are connected to the driver.

  5. FREE RUN MODE - When the FREE RUN input (Pin 10) is HIGH, the motor will run at the pulse rate at the STEP INPUT (Pin 9). When the RUN input (Pin 10) is LOW, the motor will run at 1 of 8 preset speeds that are set by 3 DIP switches (S1A, S1B and S1C) mounted on the the circuitboard.

  All of the control inputs to the EDE1200 are pulled up to 5 volts through 3.3K ohm resistors.

  For more detailed explanations of controls for the EDE1200, refer to the devices datasheet which can be found on this eLab Digital Engineering page.

FREE RUN Mode - Speed Table

  NOTE: The speeds indicated in the FREE RUN mode tables are approximate and will vary with the resonator's (X-1) actual oscillating frequency.

  NOTE: The following tables have been copied directly from the eLab Digital Engineering datasheet for the EDE1200 IC.

EDE1200 Stepper Controller Test Circuit

  The following circuit was used to test the operation and functions of the EDE1200 stepper driver circuit. In actual circuits, the inputs should be noise and bounce free although a toggle switch will work.

Stepper Circuit Board Parts

  Two sources for the EDE1200 Stepper Motor Controller IC are:

  1. eLab Digital Engineering - The manufactures 'Product Overview' page - Part EDE1200

  2. Jameco Electronics Part Number - 141532

  All other components or their equivalents are available from a number suppliers. (DigKey part numbers are shown.)

Qty.   Part #   Jameco Part no.   Description
1 - IC 1 - 141532 - EDE1200 Unipolar Stepper Motor Controller
- - - - - - -
Qty. - Part # - DigiKey Part # - Description
1 - IC 2 - 497-2356-5-ND - ULN2803 - ARRAY EIGHT DARLINGTON 18 DIP
1 - IC 3 - LM7805ACT-ND - IC REG POS 1A 5V +/-2% TOL TO-220
  - - - - - -
1 - R1, 2, 3, 4, 5 - 770-61-R3.3KP-ND - RES NET 5RES 3.3K OHM 6PIN
1 - R6, 7, 8 - 3.3KQBK-ND - RES 3.3K OHM 1/4W 5% CARBON FILM
  - - - - - -
  - - - - - -
2 - C1 - P5177-ND - CAP 4.7UF 50V ALUM LYTIC RADIAL
1 - C2 - P5156-ND - CAP 1000UF 25V ALUM LYTIC RADIAL
  - - - - - -

Static Discharge Precautions

  Although the EDE1200 is sensitive to damage from static discharge, once it is installed in its socket the IC is very safe as all of its pins are connected to the 5 volt supply or to common through low impedance paths.

  When handling or assembleing the circuitboard, avoid nonconductive surfaces such as plastics or glass. If the circuit board is to be placed in a plastic case, do the assembly work on a wood or metal surface that is connected to earth. Also avoid carpeted areas during assembly.

  A good practice is to touch the work surface before touching the circuitboard.

Circuit Boards And Parts

  The following picture is of an assembled circuitboard for the Unipolar Stepper Motor Driver. The board measures 1.9 inches by 2.9 inches and has been commercially made. The board has a protective coating on the copper side but has been not tinned or silkscreened.

  The relative positions of the terminal blocks at the ends of the circuitboard correspond with those in the schematic diagrams.

Circuit Board Prices


  If you are interested in printed circuit boards please send an email to the following address: rpaisley4@cogeco.ca Subject: EDE1200 Unipolar Stepper Driver - ULN2803

EDE 1200 Stepper Motor Driver Notes

Driving Higher Current Motors

  Stepper motors that require currents greater that 1 amp per coil or operate on less than 12 volts can be controlled by the driver by adding external transistor to the circuit and a external power supply suitable for the motor.

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Please Read Before Using These Circuit Ideas

  The explanations for the circuits on these pages cannot hope to cover every situation on every layout. For this reason be prepared to do some experimenting to get the results you want. This is especially true of circuits such as the "Across Track Infrared Detection" circuits and any other circuit that relies on other than direct electronic inputs, such as switches.

  If you use any of these circuit ideas, ask your parts supplier for a copy of the manufacturers data sheets for any components that you have not used before. These sheets contain a wealth of data and circuit design information that no electronic or print article could approach and will save time and perhaps damage to the components themselves. These data sheets can often be found on the web site of the device manufacturers.

  Although the circuits are functional the pages are not meant to be full descriptions of each circuit but rather as guides for adapting them for use by others. If you have any questions or comments please send them to the email address on the Circuit Index page.


  If you are interested in printed circuit boards please send an email to the following address: rpaisley4@cogeco.ca Subject: EDE1200 Unipolar Stepper Driver - ULN2803

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04 July, 2016