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Hard drives can be a lot of fun!
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Power a hard drive as gyroscope?

July 29th, 2020, 0:08

Hi All,

Thanks for reading this. I am new to this forum, and I am looking to see if anyone has rigged an old hard drive motor to run on a 12v DC power supply. I need to run a 3.5” hard drive on full speed (5k RPM or faster would be nice), in order to test out some gyroscopic principals when I attach the HD to an imaging platform. Basically I want to rig up some powered gyroscopes to stabilize an imaging platform. I am a handy guy, And can attach anything to most anything, but the electronics of rigging the HD itself are completely out of my wheelhouse.

If I understand correctly, a speed controller is required, but perhaps some other things are, also?

If you can point me to some how-to videos, that would be appreciated.
If you want to rig one up and send it to me, I would pay you for your time and work after we talk details.

Thanks for your consideration.

Re: Power a hard drive as gyroscope?

July 29th, 2020, 15:39

I have seen people rig up square wave drivers to each of the motor's 3 phases, but these circuits require a common terminal, ie a 4-pin motor. Most motors have 3 terminals.

You could use Seagate's 7200.12 spindle motor and PCB. The motor spins at 7200 RPM. Seagate's "green" Barracuda LP models spin at 5900 RPM. These older models allow access to the firmware via a serial terminal interface. You could issue spin up and spin down commands via a cheap PICAXE and a pushbutton as your front end, or via a laptop.

The advantage of doing it this way is that these SMOOTH motor controllers produce pseudo-sinusoidal waveforms and are able to control the speed without additional Hall Effect sensors. Of course you are then stuck with the speed that is programmed into the firmware (unless you can hack it).

Re: Power a hard drive as gyroscope?

July 30th, 2020, 10:06

Thanks so much for the reply and info! I am really out of my wheelhouse on this, and not familiar with the parts. I want to be able to have it rigged with a simple on/off button, or dial, and powered by a dedicated battery (Rechargeable lithium ion or similar).
The 7200 rpm would be great.

So, when you say I could use the seagate 7200.12 and a PCB with a PICAXE, I don’t know what that means in terms of procedure. If it is a matter of connecting wires, I can do that (with guidance). If it is a matter of software/firmware and commands, I cannot do any of that.

I apologize for my level of inexperience. Is there any setup that I could simply connect wires to some sort of controller and to a battery and make it run up to 7200RPM?

Re: Power a hard drive as gyroscope?

August 1st, 2020, 17:33

What I'm suggesting is that these SMOOTH motor controllers are best suited to the task. The 7200.12 Seagate HDDs have an accessible diagnostic terminal interface via which you could send spin-up and spin-down commands.

A PICAXE is a cheap microcontroller that can be programmed in PIC BASIC to monitor a switch press and then send spin up/down commands to the HDD. You could control several motors with one PICAXE. You wouldn't need to control the SMOOTH chips directly.

A HDD PCB can be had for less money than the power MOSFETs (3 or 6) which you would need to buy if you were to build a discrete circuit.

I'm not aware of any simple solution of the type your require. Sorry.
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