×
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

Log In

Come Join Us!

Are you an
Engineering professional?
Join Eng-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!
  • Students Click Here

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

Students Click Here

Jobs

Need a very simple variable speed stepper drive circuit (HELP PLEASE)

Need a very simple variable speed stepper drive circuit (HELP PLEASE)

Need a very simple variable speed stepper drive circuit (HELP PLEASE)

(OP)
I have an application where I will need to rotate a stepper at variable speeds from 0 to 60 rpm. I would like to have the maximum torque possible (not sure of driving configurarion desired?).
I would like to have this controlled with a simple Potentiometer. I am quite sure this can be done easily and cheaply with standard parts but at this point I am still somewhat ignorant on this issue. I am looking for input from some of you sharp people. I need to keep costs low as this is for a product I would hope less than 15$. I plan to bring to market in the future. Assume I already have regulated dc voltage I just need help with the driver circuit.
Thanks,
Mark

RE: Need a very simple variable speed stepper drive circuit (HELP PLEASE)

How much have you looked?  A little search and you can find hundreds.  A PIC and 4 transistors will do it.  If you have something that takes a lot of drive, look into LMD18245 and forget about that regulated supply.  A friend if mine is using a couple of boards from www.embeddedtronics.com  for his home made CNC.  They even give you schematic, board layout, and even software.  Your request is technically incomplete for a better answer.

RE: Need a very simple variable speed stepper drive circuit (HELP PLEASE)

(OP)
I have spent a few hours looking into it, like I said I am ignorant on the subject so that makes it more difficult.
I could use a uni or biplor stepper and the load will be very small. What information would you like to have for a complete description? I am open to any voltage of stepper I would like to run in half step mode or full step (whatever mode makes more torque?).

Sorry I do realize the question is somewhat incomplete forgive my ignorance this is not my area of expertise, that's why I am posting this here for all of you EE's and such.


RE: Need a very simple variable speed stepper drive circuit (HELP PLEASE)

(OP)
Sorry forgot to add, I need this to be completely stand alone, no software or anything. I need no positional accuracy whatsoever simply speed control.
Before you ask I do not want to use a simple dc motor due to the low torque at low voltage, a stepper would be great in this aspect. I need to keep this light and as small as possible.

RE: Need a very simple variable speed stepper drive circuit (HELP PLEASE)

light load could be handled by a plastic gear set that conviently increases your torque. Load will dictate your drive element. PWM can be had with surface mount devices.

RE: Need a very simple variable speed stepper drive circuit (HELP PLEASE)

(OP)
I need this system to run on very low power, below 1 amp @12-24vdc if possible. I am generating power with another stepper via a small air turbine. This is really not a typical application so typical solutions arent really useful. I have size, weight, power, cost, precision and reliabilty to consider.
I realize I could simply gear a conventional motor down and   
vary the voltage. I like the simplicity of direct drive. The service life of a stepper vs a brushed dc motor is also a plus.
I need to do some more studying, I see how it could be done with a pic but I was hoping for a still simpler solution.

I did find that I can run a stepper with ac using a 90° phase shift between the voltages applied to the motor's two windings with a non polarity capacitor. Perhaps this will lead me to more options as well as not requiring me to rectifty the ac output of the stepper to dc.
 

RE: Need a very simple variable speed stepper drive circuit (HELP PLEASE)

Sounds like you need to do your homework.. That is, lay hands on a few components, a scope, maybe a PIC STAMP to run things in an easy fast way, Hunt up some PIC STAMP application notes that show how to run steppers.  Fill in a whole bunch of the holes in your knowledge.  Then from the knowledge gleaned you can focus in on your specific needs with confidence.

RE: Need a very simple variable speed stepper drive circuit (HELP PLEASE)

(OP)
I think I have it figured out.

Using a non polarity capaciter and a stepping motor with 1.8deg step value.
Four steps equal 1 ac cycle.

So, this would give me an RPM of 72RPM
7.2deg per cycle * 60hz= 432deg/sec or 1.2 RPS or 72RPM
Using a solid state interval timer >20 bucks I can achieve what I am trying to do with 2% accuracy. I have found many steppers that meet the specs I require.


RE: Need a very simple variable speed stepper drive circuit (HELP PLEASE)

(OP)
I did my homework, thanks for the help ;)

Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

Reply To This Thread

Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members!


Resources