View Full Version : Stepper motor driver circuit

02-11-2006, 11:32 PM

I am a final year mechanical engineering student from India.
Now I am doing a project in robotics. We are using unipolar
stepper motors taken from old dot matrix printers for motion power.
We are using a microcontroller based board for programming and
generating signals for the required rotation.

The Motor details are

Step-Syn,Sanyo-Denki,Stepping motor type: 103-770-0178
DC 5.1 V, 1 Amp. 1.8 deg/step. Wires:6

Now we need a driver circuit for the motor. We are ready to use any
type ie.,Ic based or transistor based .

Please help us earliest.
Thank you.

02-11-2006, 11:36 PM
use uln2803 driver ic for the job.

they ll supply 600ma of current per channel.

download thedatasheets, u ll get the circuit diagrams there.

02-11-2006, 11:47 PM
thanks for your support

Sorry i am a mechanical engineering student with zero knoledge in
Our motor has a current rating of 1 amp.
Then how can we use the IC youy mensioned ?
It has six leads. Then whether it can be used as a bipolar one?

Please reply soon.

02-12-2006, 12:43 AM
A stepper motor with 6 leads can be both unipolar as well as bi-polar. You got to check out this yourself by finding out the common wire if there is any or not ? Just search the net for the procedure to find it out, its a bit lengthy so I am not writing it here.

And for driving it as Addy said you can use ULN2803 provided it is unipolar!

If it is bi-polar then go for any H-bridge IC like L293 or L298.

The circuits you can get on net , just search for them.

02-12-2006, 04:38 AM
see the diagram from

You just have to identify the leads, rest explained in diagram
For more help pm me

Bibin John

02-12-2006, 03:29 PM
Thanks for your support]

My motor Has six leads. Two of them are the center taps of
each windings. We shorted the two for connecting to
the interface card at the college electronics lab

Then , can I use this motor as a bipolar one having more torque?

02-12-2006, 06:30 PM
hey jabir.
note the schematic wat yogi has mentioned.
its good and why dont u try tat.
i m sure ur motor ll run with tat.

02-12-2006, 07:30 PM
From the message by yogi I found that my motor
can be used as either bipolar or unipolar configurations.
I choose the bipolar configuration because of the better
Now i want the detailed circuit diagram of the driver
using L293.
But there is a problem!!!!!!!!!!
Our controller board determines the distance travelled by the robot by counting the pulses given to the motor.
We also want to reverse the direction of the motor if necessary.
Can I use L293 with these?

Please reply earliest.

02-12-2006, 09:38 PM
Now i want the detailed circuit diagram of the driver
using L293.

search through the forum.... u ll get the circuit for l293 in the forum.
u ll get all sorts of details u ever wanted on l293d in the forum.

We also want to reverse the direction of the motor if necessary.
Can I use L293 with these?

obviously...... u can even do regenerative braking.

but wait!!!! l293d can support only .5amps of current per channel ... u ll have to connect dem in parallel if u want to use them for higher current applications.
or go for l298 , it supports 2amps per channel.

02-13-2006, 03:32 AM
if u use as a bipolar use L297+L298, then u can reverse motor

if u use unipolar use ULN2003, then also u can reverse motor

Bibin John

02-13-2006, 07:53 AM

05-31-2006, 05:37 PM
Hi guys...

sorry for my foolish questions ...

I made a driver ckt using TIP 122's since L293 is not available here.IT is working fine and very simple. The unipolar config has enough torque for my purpose.

The 5 volt 1 amp motors are driven by 9 volt supply. I had used 15 ohm resistances to limit the current and 3.3 k resistances for pullup in the base. 1N4148 are used as protection diodes.

Thanks everyone for the discussion...