[Robotgroup] CD/hard drive hacks?

[Gray Mack]

I think the rotation motors are fancy brush-less steppers and might take some work to convince to spin at the hardware level. With most drives (floppy, CD, hard drive) you can trace the strip cables from the motors back to the board where you will find usually 16pin chips like sn754410 with several pins heavily grounded for heat sinking that are used to drive the motors. You can look up their spec's and figure out which pins drive the current outputs? 

Once you figure a way to get the drive spinning at a constant speed, then the rest should be easier. It doesn't need to spin fast since you are recording analog audio rather than dense binary data. Ideally only a few rev/sec or slower instead of 90rps (5400rpm) so you can get many audio oscillations onto a single "track" revolution.

The power requirements of optical drive (laser) can be delicate and that's why they use feedback loops to regulate them. Magnetic drives should be easier since all you have to do is not burn out or magnetize the coil head as you are recording. Not sure if you could drive them with a simple mini speaker amplifier playing the tone, possibly! Then connect the head to an amplified input and see if it plays back. Likely someone in google land has figured out how to do this already?

Floppy drives have a much bigger head and might be readable directly, HD's may need more amplification. If you get that working then you can work on getting the head arm to move. It seems like a hack that can work, possibly at a much simpler level than what first comes to mind. For example a stepper can be driven by powering each coil in turn which could be done mechanically by hand spinning some sort of distributor.

-Gray

--- On Fri, 7/25/08, brooksdesign <brooksdesign at peoplepc.com> wrote:

> From: brooksdesign <brooksdesign at peoplepc.com>
> Subject: Re: [Robotgroup] CD/hard drive hacks?
> To: "The Robot Group Mailing List" <robotgroup at puremagic.com>
> Date: Friday, July 25, 2008, 4:11 PM
> I just sent a more focused description while you were
> replying, but yes this is what I want. But let's say I
> want to take an old cd burner, what KIND of interface? I
> guess I would need a part number for the head so you could
> track down the specs or are they mostly all the same?
> -brooks
> 
> -----Original Message-----
> >From: Andre Lamothe <ceo at nurve.net>
> >Sent: Jul 25, 2008 4:56 PM
> >To: The Robot Group Mailing List
> <robotgroup at puremagic.com>
> >Subject: Re: [Robotgroup] CD/hard drive hacks?
> >
> >Sure, you either just de-solder the connectors and
> control directly, OR 
> >write IDE interface commands to the drive and control
> the heads manually, 
> >you can seek to track, sector, etc. I have made disk
> drives play music 
> >before in the 80's (no IDE interface of course
> then), but I have done it to 
> >floppy drives and IDE hard drives. Basically, if you
> write a disk disk 
> >driver then you have to control the drive mechanics
> yourself which is what 
> >you are trying to do.
> >
> >So really all you need to do is decide on the drive,
> the interface, make an 
> >interface, and then throw commands at it with a
> microcontroller or whatver 
> >you want to connect it to.
> >
> >Andre'
> >
> >----- Original Message ----- 
> >From: "brooksdesign"
> <brooksdesign at peoplepc.com>
> >To: <robotgroup at puremagic.com>
> >Sent: Friday, July 25, 2008 3:39 PM
> >Subject: [Robotgroup] CD/hard drive hacks?
> >
> >
> >> Anybody out there ever hacked into the read/write
> heads of a hard drive or 
> >> CD burner and their actuators? More to the point
> the manual control of the 
> >> signals going in and out without the use of a
> proccessor as there would be 
> >> no need for tracking for the intended use.
> >> -brooks