View Full Version : identifying stepper motor

06-25-2008, 11:40 PM
1.I have got 2 stepper motors from my institute's electronics dept. lab.they had the codes written below

SM1&2(same model):-



7.5 deg 360 malasia

worst they do not have wiring either,but a 5 pin port as shown
. . .
. .
voltage etc...

I am working on a very important project with these motors being the life source.
Plus my location(Roorkee) does not permit me to buy any component froom market either... i am all on my own only...

2.One More QUERRY:

HOW DO YOU CONTROL STEPPER MOTOR MANUALLY(when i press a button it moves in forward direction release to stop it and another push to on to move it backward???) :?: :cry:

06-26-2008, 11:13 AM
@Samurai_01: Check these links out:

One of my most favourite EFY articles (clickie) (http://www.electronicsforu.com/electronicsforu/Articles/ad.asp?url=http://www.circuitcellar.com/avr2004/wabstracts/A3829abstract.pdf&title=Microstepper%20Motor%20Controller)
A simpler but less sopisticated method of doing the same thing, again an EFY Article (clickie) (http://www.8051projects.net/dc-motor-interfacing/l293d-interfacing-with-microcontroller.php)

Hope that helps.


Debu :)

06-26-2008, 02:01 PM
hi samurai_01


you could find the specifications on net.... just write whatever is written on motor on google.........
following sites can also help you to manually find the specifications......


a five pin slot mostly refer to unipolar motor..... you must check the phase resistance first....... it will give you an idea of motor..... mostly one with resistance below 40ohm is rated for 5 to 6 v and one with higher resistance is rated for 12v...... but its not a rule so better start with 5v.


you cant control a stepper like dc motors by just giving power supply.... read following link


first count the no of steps( degree per step) for your motor and then you can make it move to required position by either using a pc or uc........ some ics can also be used which need a pulse train at their input and generate stepper control signal at output...... link above show one such ic also.......

best of luck

06-28-2008, 02:40 PM
well its not as if i have got a problem i would just not work on it.

i have read all related posts,googled about my problem using various search terms,tried to find stepper motor manufacturer in malasia,when i have been turned down from everywhere i posted my problem on the forum as a last resort.

I respect you 2 for trying to help me out........ and
thanks for those links,but i have already seen them long before.

I know very well a stepper can't be controlled like a dc.

there is a manual stepper driver circuit using SN74194 and SN 7474,but its not that worth trying due to its non availability at farnell,tps, and many other component vendors..(not even the substitute ics)

i thought of using 2 microcontrollers,one programmed for forward motion other for reverse,and connected to a 3 way switch(On-Off-On). and proper connection with stepper...
But it would be too costly.

If anyone can help than pls...

06-28-2008, 09:19 PM
samurai.......... i think i am not able to get what you want...... so i am explaining everything to you.....

it is not necessary for you to have the datasheet of stepper before using it...... motors are not so delicate as ic's so a wrong connection won't destroy it...... OK very high voltage supply will damage it but that too will not be instantaneous and you will have enough time to switch off power..... actually it gets hot too much and you can easily sense it by touching..... and you must know that steppers are designed to run hot..... it means a temperature below 50 degrees is totally normal...... but try to keep it below 30 degrees.....

i have completed one project with stepper and my current project(micromouse) also involves steppers...... both the time my steppers were from junk.... they don't even have a single letter written on them......

what actually you need to know about stepper is:
1) steps per rotation or degree per step
2) unipolar/bipolar
3) pin configuration (sequence and comman)
4) resistance per phase
5) voltage rating

now, you could easily find out first 4 things easily..... for voltage rating do a small test.......

connect the comman terminal with ground..... now on any other terminal give a supply of 5v...... now try to turn the shaft of stepper with your hand..... you will feel steps (thats stepper)...... now its a little difficult to sense if your shaft is bare..... i would suggest to attach a wheel like structure to it..... now try to rotate it ..... if you feel the resistance provided to tou by the stepper is very low , your increase the voltage to 9v. join the power to any pin. now wait a minute and keep your hand on side of stepper .... try to sense the temperature on all sides... wait for 5 minutes....... if the temperature is normal (below 30 degreee) try to increase voltage to 12v...... if it gets hot switch off power..... you are near to maximum rating and i would recommend you to use stepper below this voltage...... now feel the resistance..... more the resistance offered better is the torque and better is your motor....... make sure your power supply can provide upto 1A current before trying it out........ (i tried this way upto 50v and my stepper was not even getting warm and i was also not getting the enough torque ....and after 3 weeks of investigation i found out that the transformer i was using was not even giving me 200mA).

now come to your second problem

thought of using 2 microcontrollers,one programmed for forward motion other for reverse,and connected to a 3 way switch(On-Off-On). and proper connection with stepper...

two microcontrollers for 1 stepper????????????? 8O 8O 8O 8O 8O

dude, if you really know the power of a microcontroller(uc) you would not have thought of such a solution....... a simple uc (8951, atmega8) have 3 8-bit ports .... so you can control 6 steppers at the same time with dedicated contol lines ( one bit one line)...... you can increase the count to even thousand by using some external circuits. (something like demultiplexing).......

for some idea connect the direction pin with interrupt..... every time a interrupt is given the program reverse the direction....... if you want to add more functionalities like speed, various driving modes, pick and release motion( as used in automated cranes), etc you can work this way.... whenever you want to change anything give interrupt..... the program associated with your interrupt should call a routine which demand input on a port. in the input you give the code which you have already associated with specific tasks...... you campare the input(in uc) and do what it should do........ its easy isn't it........

now your third problem

there is a manual stepper driver circuit using SN74194 and SN 7474,but its not that worth trying due to its non availability at farnell,tps

if pcb space is not that big problem you can easily make stepper driver circuit within an hour...... you just need ULN 2803/2003....... i would also recommend to use opto-isolators between your uc and ULN..... it will save your uc from any reverse current and sharp pulses which can reset your uc or can even damage it...... you can easily find a circuit on net.......

now, if you have any querries remaining don't hesitate to ask them..... but i would suggest you to properly state what actually is the aim of your project. (i still dont know what you r thinking to do with those streppers) .... if anyone of us had done such project he can provide better help........

best of luck......

06-29-2008, 12:21 AM
@ ashish

Thanks for taking out time and giving me such an excellent advice. :D :D :D