Article

First Steps

Everything you need to know to drive a stepper motor

Stepper motors have found their way into Elektor Electronics many times, most recently in the November and December 2003 issues. In contrast to previous articles, we’ll keep it practical and won’t go into the theory. If you want to know more about the background, have a look at some previous articles (listed in the reference section at the end of this article).To get an unknown motor to work you really need to do two things: find out what properties your motor has and choose the right driver electronics. With the help of this article you will find that it’s not that difficult. The following three steps will help you discover the most important properties of a motor. The first step helps you determine whether you have a bipolar or unipolar motor.

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Materials

030203-12.zip

030203-PCB.pdf

Gerber file

CAM/CAD data for the PCB referred to in this article is available as a Gerber file. Elektor GREEN and GOLD members can exclusively download these files for free as part of their membership. Gerber files allow a PCB to be produced on an appropriate device available locally, or through an online PCB manufacturing service.

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PCB

Download Gerber file: 030203-1.zip

Extra info / Update

In the circuit diagram the value of R17 and R18 is shown as 10 k, while 1 M appears in the parts list. The value is not critical but in practice 10 k will provide the best protection against noise at the FET inputs.

Component list

For 5-9 V (values for 9-15 V in bracket)
Resistors:
R1-R4,R8-R11 = 2kOhm 2 (4kOhm 7)
R5,R12 = 560Ohm (1kOhm 5)
R6,R7,R13,R14 = 1kOhm
R15,R16 = 1kOhm (2kOhm 2)
R17,R18 = 1MOhm
Capacitors:
C1-C4 = 10nF
C5,C6 = 100nF
Semiconductors:
D1,D3 = LED, red, high efficiency
D2,D4 = LED, green, high efficiency
T1,T3,T6,T8 = TIP127 or IRF9520 or diode MBR745 *
T2,T4,T5,T7 = TIP122 or IRF520
T9,T10 = BS170
IC1 = 4049
IC2 = 4093B
Miscellaneous:
14-way IC socket
16-way IC socket
Flash Micro Board software, Free Download, file no. 030203-11
* if you do not use bipolar transistors or FETs, diodes must be fitted! This applies to the use of a unipolar motor.