<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN">
<html><body style='font-size: 10pt; font-family: Verdana,Geneva,sans-serif'>
<pre>Brian,
If you're using the Pololu stepper drivers you got from me, you should be in luck. It's not so much the voltage that poses a danger to the stepper, but the current. The Pololu stepper drivers have adjustable current limiting built in, so you can drive the steppers with significantly higher voltage than what they are rated for. This has the advantage of better performance and max step rate from the motor, but at the cost of higher overall power consumption. My CNC drives 3-5V steppers with 12V supplied to the driver boards, and supposedly I could go higher if I wanted.
Also, those drivers have distinct logic and motor drive power Vin's so you can drive the logic input directly with your MCP23008 or Raspi GPIO. (A word of warning though, using an I/O expander to drive a stepper pulse is going to be pretty slow)
Someone correct me if I'm wrong, but I think the rated current of a stepper can be found simply by I = V/R where V is the rated input voltage, and R is the measured coil resistance.
The instructions for setting the current limit on the driver is here, under "Current Limiting":
<a href="https://anibit.com/product/mtr04001">https://anibit.com/product/mtr04001</a>
<br />--Jon<br /><br />
On 2015-03-18 15:50, Grawburg wrote:
> I've got a Sanyo Denki Type 103-546-8441 stepper (2.4 ohm, 1.8
> deg/step, 4-wire). Trying to find reliable voltage numbers has proven
> a bit frustrating, but it seems to be 3.2 to 3.6 VDC. If I understand
> some of what I've been reading about bipolar motors, running it at a
> slightly higher voltage (i.e. 5) is not likely to cause a problem.
>
> The question I have has to do with the controller cards I want to use
> (and all that I've seen mentioned) that require a minimum of 8 VDC.
> Clearly I will need a level shifter between the controller card and
> the Raspberry Pi or the MCP23008 I/O expander. If the controllers
> require 8 VDC does that mean I will be powering the stepper with 8 as
> well?
>
> From the Python code I've found controlling a bipolar is a bit more
> involved than the small unipolars I've been playing with.
>
>
> Brian Grawburg
>
>
>
>
>
> _______________________________________________
> Triangle, NC Embedded Computing mailing list
> TriEmbed@triembed.org
> http://mail.triembed.org/mailman/listinfo/triembed_triembed.org
> TriEmbed web site: http://TriEmbed.org
--
Jon Wolfe
Anibit Technology LLC.
https://anibit.com</pre>
</body></html>