DC Motors

Hello, I have a Brushless DC Motor made by Mystery with part number D2825-5000 on it. It is an 11.1V 16,000rpm motor. I have 12v supplied to it(operating range of 6-18v it says) from an old AT power supply. Problem is that the motor has 3 wires: red, black, and yellow. I can't figure out how to wire the thing up to get the arduino to control it. Thanks for any suggestions!

Hello, Brushless motors work on a different principle than that of a standard brushed DC motor. In your example, if you had a brushed motor, then the motor would spin when you applied the voltage from the power supply. In a brushed motor, voltage applied to the commutator creates the magnetic field, turns the motor, which then breaks that contact, and creates the next magnetic field with the next contact. Brushless does not have the simplicity of that, so it must create the phased magnetic fields without the benefit of the mechanical contacts. So that is why it has multiple leads on it - it is essentially three phased alternating current timed to at X frequency to create the rotation and speed. http://en.wikipedia.org/wiki/Brushless_DC_electric_motor heheh, the above link explains it much better than myself :)

So the net result - is you should build/buy a brushless motor controller (which provide the subsequent drive circuits which the arduino doe not have the power for) and then use the Arduino to send the control signals to that.

Hope that helps :)

Thanks!...what does building one entail? Im pretty low on budget for this project

Well, IMHO if you are on a tight/low budget (As I am!) then going brushless probably is not the right direction. With a standard brushed DC motor, you can order the SN754410 from sparkfun for a few dollars, and the circuit is relatively simple. Sparkfun link http://www.sparkfun.com/commerce/product_info.php?products_id=315 Link to circuit building info http://lab.guilhermemartins.net/?p=66 *This page references the L293, however this ic is the same as the one I mentioned above, so just substitute the one above for the 293. The SN is higher power is primary difference. I am not sure why you started with brushless, just making a suggestion above is all. If you need to run with brushless, I havent done much research into the DIY circuits for those - perhaps someone else here would have that info. :)

I agree with the view that brushless motors may not be the best choice here, but if you do need a low cost speed controller for your motor, you have, this one is under $12 shipped. http://www.dealextreme.com/details.dx/sku.11981

Hey great!...Does this mean it will work with my Mystery D2825-5000 brushless DC motor...it's an 11.1V motor...my power supply from an old AT that i just got working today provides 5V,12V-5V-12V...it's a 23A 230W power supply...i'm building a laser light so the variable control might be nice if anyone has any familirity with PWM and motors that would help too, although i have only one arduino so i'm not sure how i can hack this code up to also put out to the motor while it's putting out to the LED arrays(from my other posts)...anyone know of a good place to get defraction grating? or what kind of equipment it comes in that i can find trashed...sorry, this truly is a low budget project so if I have asked any questions that are not forum related, my appologies...Thanks!

That speed controller looks like it would be ok with your motor. What is it that the motor is going to drive?

It will spin a defraction grating through which the laser will pass

Your motor spins at 5000 RPM per volt, are you using gear reduction?