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Topic: Unsure which motor controller to use (Read 815 times) previous topic - next topic

dmor574

I'm trying to power these 2 motors (http://www.parallax.com/tabid/768/ProductID/587/Default.aspx) with an arduino mega. I originally chose this motor controller (http://www.sainsmart.com/sainsmart-l293d-motor-drive-shield-for-arduino-duemilanove-mega-uno-r3-avr-atmel.html) to drive them.

(I don't know too much about electronics, so correct me if i'm wrong). But the sainsmart motor controller states that it gives each motor .6A, while these motor's stall torque is rated for 4.8A. This would mean that the motors would never get enough power to use even half of the motor's strength. I recently found this motor controller: http://www.pololu.com/catalog/product/2503.

The pololu motor controller seems like it can do the job, but I'm honestly not that knowledgeable in the specifics of electronics. Any other suggestions or recommendations would be appreciated.

Note: if you would like to know what the power source will be: http://www.valuehobby.com/power-systems/lipo-batteries/30c-2200mah-2s-lipo.html

Thanks for any help.

johnwasser

"Its dual MC33926 motor drivers operate from 5 to 28 V and can deliver a continuous 3 A per motor."

Still not good enough for a stall current of 4.8 A.  I'd look for a driver capable of a continuous 5 A or more.  You don't want the motor burning out your driver board.
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dmor574

#2
Jan 28, 2013, 02:31 pm Last Edit: Jan 28, 2013, 02:42 pm by dmor574 Reason: 1
Can you give me a quick explanation of how the current works? I'm still pretty confused as to how it works. Does a motor draw only the current it needs, or can having 10A damage the motor?

There was a higher power alternative: http://www.pololu.com/catalog/product/2502

Would the one I just linked work properly? Are there any cheaper alternatives that won't compromise quality and effectiveness? This one seems over powered for what I need.

Chagrin

The motor only draws as much current as it needs. The more load it is under the more current it will draw, up to the point where you stop the motor completely where it draws the most current -- its stall current.

"Having 10A available" does not mean it will ever draw 10A, just as when you screw in a light bulb it never takes down the local power plant. The internal resistance of the motor, created from incredibly long windings of thin wire, limits how much current it will take.

I'd respectfully disagree with johnwasser on the MC33926 board. The docs state that the chips are rated 5A continuous if you add heatsinks or other cooling. It also has thermal shutdown to prevent it from overheating. If you're just running around on smooth/flat surfaces I wouldn't expect any issue.

TeslaIaint

Do your motors need to spin in both directions?

dmor574

Definitely. and I prefer a shield to make it more compact and less soldering, I don't have time to create my own board.

dc42


Definitely. and I prefer a shield to make it more compact and less soldering, I don't have time to create my own board.


http://www.pololu.com/catalog/product/2503
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dmor574

Thos only deliver 3A when the motors require 4.8A for max torque

Chagrin

Is it just me or is this going in a circle?

dc42


Thos only deliver 3A when the motors require 4.8A for max torque


I suggest you read the product information page. It says they can deliver 5A for short periods.
Formal verification of safety-critical software, software development, and electronic design and prototyping. See http://www.eschertech.com. Please do not ask for unpaid help via PM, use the forum.

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