drive stepper motor at constant speed

Projects General Guidance
1

Hello,

here is my first post here.
I'd like to drive hdd motor at a 3600 rpm constant speed (not 3599 or 3601).
I think this kind of motor are unipolar stepper motor so I'd like to make this hardware:
http://www.arduino.cc/en/Tutorial/StepperUnipolar with the uln2003

So here"s my question will I be able to reach the 3600 rpm with arduino interface
(my hdd motor is designed to work at 5400rpm)?

Will this speed be constant (assuming 3599 or 3601 is not acceptable)?

at my last question can I try to make my board alone like this:

Thanks in advance for help

2

Hi, You need to get more information about that motor.

It is very unlikely that it is any kind of "Stepper motor"...

3

well

4

Yes, those are stepper motors. They are used to position the disk drive heads.

The spindle rotation motor is a different type and usually has electronics on the drive circuit board to regulate it's speed.

Unfortunately two very different things...

But old stepper motors in disk drives and printers can be made to make cool things! Take a look at this one:

5

Ok ok sorry for this misunderstanding.
Let me change my questions: I just would like to drive an electric motor to run at 3600 rpm (very very stable).
What type of motor should I use and how could I drive it?

Help I got lost
thx

6

What type of motor should I use and how could I drive it?

One that has feedback that allows you to KNOW how fast it is running.

What are you trying to do? Typically, rotational speed does not have to be less than +/-1 RPM.

7

Hello

I'd like to make a sort of 3D dolby system.


My first goal is to have a disk turning in front of a video projector and in sync with the refresh rate.
As I asume a video refresh rate is very stable I need a very stable rotation speed to stay in sync.

Do you think it's possible ? (well dolby is able to)

thx

8

and in sync with the refresh rate.

So that's the bit you didn't tell us.
You can't just run a motor (or anything) and hope it will stay in sync, it simply will not no matter how stable you have the speed, it is not possible.
What you need to do is to synchronise a motor to the frame rate.

I have done this using a phase locked loop with an opto sensor on the motorised shutter acting as the VCO using normal DC servo motors.

9

Hello,

here's the concept:

In fact the only synchronisation I need is the motor rotation speed and the shutter glasses frame rate (120hz).
I already got the shutter synchronisation system :
http://www.mtbs3d.com/phpBB/viewtopic.php?f=26&t=12596
As far as I have understood the IR signal is only used to initialize to shutter glasses (the refresh rate is fixed @ 120hz)

Do you have a schema for arduino to drive a dc motor with opto sensor to keep the motor in sync with a 60hz clock signal (60hz crystal for example)

Thx in advance

thx

10

That is exactly what I did in 1993
Look at the diagram for Twin Peeps in this link, it is a TIFF file so down load it if your browser can't cope:-
http://www.doc.mmu.ac.uk/STAFF/A.Wiseman/Acorn/BodyBuild/BB93.html
My system did run at a 50Hz frame rate but there is no reason why you should not run it at 120Hz

As far as I have understood the IR signal is only used to initialize to shutter glasses

No it is used to drive it and so keep it in sync, there is nothing free running, as I said free running at whatever degree of accuracy doesn't work with anything anywhere in the universe.

11

Yes thx your project will help me a lot.
I've tried to pm you for additional questions