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How to run hard drive motors?

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LAN_403

FastMHz

Thu Apr 27 2006, 10:38PM

Registered Member #179 Joined: Thu Feb 16 2006, 02:08AM
Location: Hagerstown, Maryland - Close to Prime Outlets
Posts: 287

Hi all - I just ripped into a ton of old hard drives and have these nice brushless pancake motors as a result. Some have three wires, some have 4, and a couple have quite a few more. What kind of driver would I need to spin these up? Unfortunately the HDD circuit boards don't run them long or at all as the heads,etc are missing and so it shuts down the motor.

Marko

Thu Apr 27 2006, 10:59PM

Registered Member #89 Joined: Thu Feb 09 2006, 02:40PM
Location: Zadar, Croatia
Posts: 3145

If you use the board, you must seek for a datasheet of the main motor controller over there, and pick around it until it surrenders and decides to run the motor.
Usually you just need to pull down some enable pins, it is very easy thing to do actually.

Hard thing to do is to run such motors independently without a specific IC; you could try to emulate 3-phase drive, with basic logic I think you will just end in a big mess.

You can try to see how it spins using low-freq AC, at few volts. You need at least 2 phases appllied to two windings, so you need few uF capacitor in series with one.

Motor will start to spin, but very slowly and vibrating.

I do this only if I need to test them, , and this method seems uselles in practice.

So best try would be mcu (pic, atmel...) with some output drivers.

cheers

FastMHz

Thu Apr 27 2006, 11:49PM

Registered Member #179 Joined: Thu Feb 16 2006, 02:08AM
Location: Hagerstown, Maryland - Close to Prime Outlets
Posts: 287

Thanks for the info! I'll have to see what chance I have of ripping the controlling IC off the board...or perhaps try to find a generic three phase controller chip of some sort.

ragnar

Fri Apr 28 2006, 12:55AM

Registered Member #63 Joined: Thu Feb 09 2006, 06:18AM
Location:
Posts: 1425

I've found it best to just use the original driver circuity..! I can't emphasise this enough. If you've got a large enough selection of drives, you'll find at least 2/3 of them are not 'too smart' to power up the motor when the read-heads etc are removed.

If you can remove the controller board and by surgery extract the platters and the motor, just plug them into any old AT power supply and they'll work! If they don't... toss the controller boards and save the motors for a rainy day when you want to design your own.

You really can't beat the inertia/load compensation, spin-up and spin-down, speed maintenance etc that comes with the original controller... just don't burn yourself on the chips - some of them get rather (stinking) hot if the readheads are removed.

Carbon_Rod

Fri Apr 28 2006, 03:00AM

Registered Member #65 Joined: Thu Feb 09 2006, 06:43AM
Location:
Posts: 1155

I have driven these with simple DC switching just to see if it could be done. As far as I can tell the motors in running hard drives are not that powerful even with their original drivers. They are high speed and well balanced â€“ So I was working on building a simple gyroscopic device using these (opted for plan B). See old.4hv.org for the details.

Cheers,

FastMHz

Fri Apr 28 2006, 04:50PM

Registered Member #179 Joined: Thu Feb 16 2006, 02:08AM
Location: Hagerstown, Maryland - Close to Prime Outlets
Posts: 287

Yes, I did find that all the Seagates I took apart will keep spinning without the heads...the others just don't start at all, or spin up and then immediately shut off.

I'm going to check Carbon_Rod's old posts 'cause there's nothing more fun then hacking something together

Part Scavenger

Fri Apr 28 2006, 05:26PM

Registered Member #79 Joined: Thu Feb 09 2006, 11:35AM
Location: Arkansas
Posts: 673

There's something you can do with levitation, let's see if I can find it...

Here it is.

You can do this too:

Or make a clock:

I've read somewhere about speakers too...

Wolfram

Fri Apr 28 2006, 06:09PM

Registered Member #33 Joined: Sat Feb 04 2006, 01:31PM
Location: Norway
Posts: 971

Conundrum

Fri Apr 28 2006, 08:40PM

Registered Member #96 Joined: Thu Feb 09 2006, 05:37PM
Location: CI, Earth
Posts: 4062

if anyone wants them i have a stack of used hdd pcb's and motors, make offer inc p&p :)

i was going to dump them but i know they are useful.

also have stacks of hard disk platters for salvage (maglev) and magnets.

email me on mandoline at c w g s y dot net

tks
-A

"Bother" said Poohs, as they realised the quantum mirror was faulty...

FastMHz

Sun Apr 30 2006, 05:09PM

Registered Member #179 Joined: Thu Feb 16 2006, 02:08AM
Location: Hagerstown, Maryland - Close to Prime Outlets
Posts: 287

Thanks for the project ideas everyone! I had known about the levitating magnets over aluminum, but those clocks and other things are very unique.

Does anyone know some specifics about how these motors actually work? Some have 4 poles, and some have many more. Does the circuitry in effect power the coils in series pulses to "pull" the magnet/armature around? Or is it more complicated? I did track down the chip that runs them on the seagates...and it's the size of a darn 8088 CPU...that's a lot of pins to figure out...and desoldering is out.

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