Welcome to our site!

Electro Tech is an online community (with over 170,000 members) who enjoy talking about and building electronic circuits, projects and gadgets. To participate you need to register. Registration is free. Click here to register now.

  • Welcome to our site! Electro Tech is an online community (with over 170,000 members) who enjoy talking about and building electronic circuits, projects and gadgets. To participate you need to register. Registration is free. Click here to register now.

how to use hard disk spindle motors

Status
Not open for further replies.

DrIguana

New Member
Hi guys,

Just though I would add my 2 cents worth. I've also played with these motors a bit. The motors I've seen also have their coils in a Y configuration with a tap in the middle. I use a different driver but otherwise my approach is very similar to that of be80be.

The problem I found is that the timing is critical. When I used fixed delays the rotation is not very robust. Sometimes it would spin up, other times not. Sometimes it would spin for a while and then lose sync and stutter to a stop.

When used in a hard drive, the magnetic information on the drive platters is used to synchronize the coil timing to the rotation. Coil transitions occur at just the right moment and the motor accelerates strongly and holds speed against all perturbations.

I made a simple optical encoder disc using a laser printer and a transparency. I used an optical interrupt switch to sense the black to transparent transitions and used this to clock the coil transition. The change was dramatic. With this feedback I could easily reach the rated speed of the motor. After slowing the platter with a finger, the motor would rapidly recover its speed.

A friend of mine, Paul Rowntree, adapted this approach for use with the propeller chip and posted the project at

Propeller Object Exchange

Hope this is helpful.

DrIguana
 

HATHA

New Member
if the HD motors are BLDC then doesn't it have some hall effect sonsors, is it possible to sens the rottar via such hall effect sensors
 

Frankco

New Member
Hi Hatha,

You probably know this but, the position of the spindle is "written" on the platter of hard drives. All that is gone with the removal of the platter and the read head. In the link DrIguana provided they replaced the position information with a transparent disk mounted to the spindle and a sensor for feedback.

There are chips out there that will use back EMF sensing for sensing the position of the spindle motor.

Would this chip work for that?
"Connections for TPIC43T01 and Discrete Power NMOS FETs"
https://www.electro-tech-online.com/custompdfs/2009/07/slit117.pdf
 

HATHA

New Member

malekblbl

New Member
the brushless motor with 4 wires means that its star winded, with 3 wires means delta winded, to controle it try the TDA5140A...
see this image
294-sterownik_1920.jpg
 

Frankco

New Member
the brushless motor with 4 wires means that its star winded, with 3 wires means delta winded, to controle it try the TDA5140A...
see this image
294-sterownik_1920.jpg

Thanks malekblbl,

Do you know of a good source for the TDA5140A? The source I found runs about $16 ea. with shipping included.

Frank
 

Frankco

New Member
Thanks malekblbl! You made my day.

I have a lot of hard drives that I want to turn into compact small orbital shaker tables. I need to be able to control the speed from 0 to about 45rpm. I'm not sure if this chip will do it or even the hard drives but I'll give it a try. Oh, the tables are needed for plant cell suspensions. I am growing individual plant cells trying to cross them with unrelated plants. Kind of making a new plant that hasn't existed before. Weird I know. I'm a science geek. I have some vids on YouTube that are a few years old. I'm trying more advanced things now. YouTube - fbt2007's Channel

Thanks again,
Frank
 
Last edited:

malekblbl

New Member
you can control the speed of the motor using this ic with controling the voltage of Vmot and its simple....
but i want to know if i can control 2 identical brushless motors with the same speed using a single ic or two cascaded ic's
 

karusel

New Member
Hello :)

I've been searching the web for a while, but I found most information I need in this thread it mostly just cancelled the ideas I've had and raised additional questions.

I have a small project going - I would like to use 3 15K Cheetas as gyroscopes. I understand now, the by far easiest way to do that would be by keeping them as they are and simply putting the power to the connector pins. Trouble with that is that the drives are incredibly heavy (over 1.5lbs) and that would be pretty much useless for me. If I strip them down, the read/write head must go too, so do I assume correctly the speed information fed to PCB will be lost and the drive will not spin normally? Ideally, I would strip the drive down to the spindle motor and platters, period. If there is no other way, I'd have to keep original PCB's, but there's less problem with that, than keeping that load of dead weight.

Unfortunately I'm not an expert in electronics - a nice portion of this thread is like french to me, is there a simple way to make the drive spin at a constant speed without the R/W head?
 

Hero999

Banned
It seems like an expensive solution unless you got some second hand broken drives for cheap.

What about just buying some cheap high speed DC motors and mounting metal discs to them? You could use a heavier metal such as steel so it doesn't need to run as fast or the rotor can be smaller.
 

karusel

New Member
Yes the price was reasonable... the problem with doing stuff like that from the scratch is that it would be very difficult to kill vibrations, which is one of the reasons for building a gyro in the first place. HDD's spindles/platters are absolutely perfectly balanced or - way better than I could balance them.
 

Hero999

Banned

ashonic

New Member
Hi frnds
I've got n seagate spindle motor ( 3 pins ) .....
when i supply current, it just jerks and stops .......
wat 2 do...
 

alec_t

Well-Known Member
Most Helpful Member
You have just responded to a 5 year old thread! Better to start your own.
Did you read the answers in the thread?
BTW, welcome to ETO.
 
Status
Not open for further replies.

Latest threads

EE World Online Articles

Loading
Top