Bipolar Stepper Control Help?

Just started working with my arduino and I am quite pleased with it, but have run into a bit of trouble getting the stepper motor from a cd drive to work.

I made an H bridge to help power the motor, and it seems to be working properly, but when i start running the arduino the stepper just sits and makes a soft buzz.

Ive noticed that while the arduino is working, the stepper becomes easier to turn by hand in the intended direction and harder in the opposite.

I am using the stepper library, and have the motor set to 100 steps with a speed of 200 (though i have been changing these values for testing).

Thanks in advance for any help availible!

What i mean is that I have tested the H bridge without the stepper, and it does work the way i expected it to (current flows based on the input).

I suppose i dont really know if the bridge is working correctly with the stepper (swithcing too slow?) but as far as i can tell it is doing what it is supposed to do.

Thanks for the reply!

What voltage are you applying to the H-bridge? What components are you using to implement your H-bridge? Is there a schematic?

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The Quick Shield: breakout all 28 pins to quick-connect terminals

Im running it off of 9v (also used to power the arduino)

the circuit is this (only with the 9v mentioned)

http://www.solarbotics.net/library/circuits/driver_4varHbridge.html

That circuit will not work reliably at 9V. It really was only meant for operation up to 5V.

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The Quick Shield: breakout all 28 pins to quick-connect terminals

Would i be able to simply run it off of the 5v from the Arduino then?

It really depends on how much current your stepper motor requires. Also, do you have two of those H-bridge circuits? As Richard Crowley said, you cannot control a bipolar stepper motor with a single H-bridge; you need one H-bridge per stepper coil.

  • Ben

the 9v is indeed from one of the small square batteries, but i believe i have a 9v wall supply somewhere if i should give it a try.

i do have a second identical h bridge for the second coil as mentioned

and it shouldnt have too high of a power requirement (see the link)
http://robocup.idi.ntnu.no/wiki/images/c/c6/PL15S020.pdf

If you don't have a way to limit the current, you should not be exceeding 5V. At 9V, each powered coil is going to draw almost an amp, which is way more current than you should be trying to pull from a 9V battery (9V batteries should not be used for high-current applications like powering motors), and which is also too much for a lot of wall supplies.

  • Ben

He posted a datasheet a few posts up for a bipolar stepper motor rated for 5V (10 ohm per coil, or 500 mA per coil).

i do have a second identical h bridge for the second coil as mentioned

Huh? If your motor has 4 wires, it won't run if you are only powering 2 of them.

I'm not following you here. Each H-brige powers a coil (two wires, one connected to each half-bridge), so there is no problem connecting four wires to two H-briges.

  • Ben

I'm admittedly biased, but my recommendation is to use a dedicated bipolar stepper driver with the highest voltage available (and a source capable of delivering the necessary current). It will limit the current for you (without dumping power through resistors, though that's probably not a big concern if you're using a wall supply), and the high input voltage will cause the current to ramp up faster, which in turn means higher torque and a faster maximum step rate. You can pick one up during the Black Friday sale for $7.75.

  • Ben

I appologize for not being very specific. Bens is right, the datasheet I posted is the motor I am using (4 pin, 5v) .

For simplicity, im thinking about just getting an actual stepped driver (probably during the sales as he mentioned)

Do you have a driver you would recommend? Ill be willing to pay for a decent one that I could use for larger projects if that's possible.

Also to add clarification, I am planning on using these motors as part of a 3 axis plotter. I decided to do some testing using the arduino as a simple interface and to get some experience working with steppers

Sorry, missed the link to the driver.

Sorry, missed the link to the driver.

I keep forgetting that links on this forum don't stand out very well. The stepper motor driver I linked is popular among RepRap builders, (RepRap machines are home-made 3D printers). You might find some useful tips on the RepRap forum. Note that you will probably need to add your own heat sinks if you switch to larger stepper motors.

  • Ben

I recognize the Mendel X carrage, but what was the other x carrage there?