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Computer controlled DC motor speed

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DSGarcia

New Member
I am looking for a DC motor speed controller and need some help with my search (I am having problems coming up with the proper search terms that yield useful results). Here are my requirements:

I need to control the speed of an 1/60 HP 24VDC motor. I have 13VDC available (auto battery) but only need to turn the motor less than half speed. I would like to control the speed from a computer (using either RS-232, RS-485, or Ethernet). I can find D/A modules that produce a low current DC voltage or PWM if that would be helpful as an input for a DC motor speed controller.

I would rather find something I can purchase off-the-shelf because I don't have extra time available to devote to building/programming/testing my own controller.

Any suggestions on where to look or how to specify such a controller?

Thanks,
Dale
 
I am looking for a DC motor speed controller and need some help with my search (I am having problems coming up with the proper search terms that yield useful results). Here are my requirements:

I need to control the speed of an 1/60 HP 24VDC motor. I have 13VDC available (auto battery) but only need to turn the motor less than half speed. I would like to control the speed from a computer (using either RS-232, RS-485, or Ethernet). I can find D/A modules that produce a low current DC voltage or PWM if that would be helpful as an input for a DC motor speed controller.

I would rather find something I can purchase off-the-shelf because I don't have extra time available to devote to building/programming/testing my own controller.

Any suggestions on where to look or how to specify such a controller?

Thanks,
Dale

Hi

Googled RS232 motor controller and came up with plenty of results.

Cheers
 

DSGarcia

New Member
Hi

Googled RS232 motor controller and came up with plenty of results.

Cheers

Mark,
Thanks for the help. I did not include RS232 in the search terms before because I had several different interfacing methods I could have used. However, most of the results were for stepper or servo motor controllers (which I don't need) though I did find a company named Pololu which I have to research some more. I will play around with search terms some more to see if I can get more useful results.
Thanks,
Dale
 
Last edited:

DSGarcia

New Member
I found a Pololu DMC02 motor controller that interfaces with RS-232. To avoid a long discussion on my difficulties of finding answers and unreturned calls from various parties, let's say that I still have a few unanswered questions.

The motor is a 24 VDC motor with brushes, 1/60 HP, 45 RPM. (It is in another state so I cannot look at it until I have my solution and go to it for testing.)

I presume that the motor speed can be controlled by PWM and does not need a fixed DC voltage, correct? (The manufacturer of the equipment incorporating the motor claimed it needed a fixed DC voltage proportional to speed not PWM, but they also claimed that they use a SCR to control the voltage which doesn't make sense--I think they do not know what they are talking about).

The Pololu DCM02 delivers 2.5 amps continuous, is that enough for a 1/60 HP motor or do I need more power?

For DC motor speed controllers, what does it matter if the motor has brushes or is brushless? I have found some controllers for brushless DC motors.

Thanks,
Dale
 

Mr RB

Well-Known Member
1/60 hp is under 15 watts so that would be 24v @ 0.6 amps or so. Running at 12v should be less amps again, so I think a 2.5A controller would work it fine.

PWM averages out to something like a constant DC voltage, just you can adjust the "voltage" to set the speed you want.

Just keep in mind that its only a little motor, and running off a much lower voltage it won't have very much power.
 

lxkarthi

New Member
hey look at Electronics for you magazine... it has the computer motor speed controller (i think it's a stepper motor)
if you want a DC motor speed controller i can design for you :) and i will give you the scematics and program..
my email id is karthi.amrita.cbe@gmail.com
 

DSGarcia

New Member
Thanks for the information. Not that it matters at this point, but I am curious about one thing still. Some controllers mentioned that they were for brushless DC motors. What is the difference between controls for a brushless vs brushed motor?
Thanks,
Dale
 

Nigel Goodwin

Super Moderator
Most Helpful Member
Thanks for the information. Not that it matters at this point, but I am curious about one thing still. Some controllers mentioned that they were for brushless DC motors. What is the difference between controls for a brushless vs brushed motor?

Brushless DC motors often don't move at all unless you have a controller for them, they require electronics to move.
 
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