moving a bipolar stepper with a B.Stamp more Faster !!! ( I need more than 500 rpm)

markuster

Hi,

I tried to move the Parallax unipolar stepper but the speed was about 200 rpm with low torque.
I was using about 6 volts and then 12 volts and the ULN with a B. Stamp 2P

Then I hear that bipolar steppers were faster but the speed was almost the same.

Finally I hear that I have to increas voltaje and keep amp. to increase the speed
of steppers.

Somebody knows something about this ?

Perhaps the problem is B.Stamp that are slower than a PIC microcontroller .

I saw an stepper moving at more than 2,000 at youtube ( Is this possible ?
with a B. Stamp)

Do you know where is my problem?
THanks Mark

Martin_H

My first stepper motor experiments involved a BS2 and pulsing the coils directly via some TIP 120 transistors. Like you I found I had a hard time achieving any speed and I got my hands on a stepper controller based on the Allegro A4988 (both SparkFun and Pololu sell them). At that point your MCU talks to the stepper using three pins for enable, step, and direction. You set enable and direction and then rapidly pulse step in a loop and can achieve much higher step rates. I later switched to the Propeller using Spin to achieve even higher step rates, although the BS2's freqout command might have worked too.

One thing I've noticed with steppers is that they need to be ramped up to speed or else they'll stutter and do nothing. I've also found they lose torque at high speeds and found 800 to 1000 RPM was as fast as I could go.

erco

500 RPM is pretty fast for a stepper. To get anywhere close to that, you will need a MUCH higher voltage supply than the motor is rated, FYI. What voltage are you using now? See useful info at http://www.picaxeforum.co.uk/showthread.php?20357-Stepper-motors-the-next-level&highlight=stepper+motor