While this is possibly more of a Super-User question, I chose to put it in EE because I'm looking for information about power assignments on SCSI cables, and understanding how to send power ONLY (not data transmission) to a SCSI drive via it's ribbon cable or some other method. I figured that's going to involve schematics and likely some soldering...hence, EE. :)

I`m building a DIY gyro-stabilizer for a camera, and have determined through a few experiments with long ribbon cables that two 10000rpm SCSI drives offer just the right amount of resistance for the device I'm stabilizing. Once I'm disconnected from the computer/SCSI card, though, I have no power to the drive. For an IDE drvie, I'd just solder a battery holder to a molex connector and be done with it. All I need is for the drive to spin.

SCSI 160 (16Bit
This SCSI Ultra160 (16-bit, if it matters) connector is what I'm working with, but I can't seem to find any pin-out information that tells me which of the pins/cables supplies power to the drive. I'm also interested to know if there are any hardware mechanisms in SCSI that would cause the hard drive to stop spinning. For instance, there may be a 3V connector somewhere that causes a standby mode if I don't connect that as well. I'm not sure if there's anything like that hidden in the ribbon cable of which I need to be aware.

Can anyone help? Does anyone have experience doing this?

  • \$\begingroup\$ +1 for MacGyvering a gyroscope out of a couple of hard drives. :) Unless you just had them lying around, though, it seems to me that you could build your own gyroscope pretty cheaply. \$\endgroup\$
    – cHao
    Commented Dec 23, 2013 at 6:25
  • \$\begingroup\$ @cHao Yep, I had them lying around. I was trying to duplicate makezine.com/2012/03/12/… even cheaper. But...I'm interested in how I would build my own gyroscope pretty cheaply...I'd prefer a smaller form factor than a pair of scsi drives. :) if you ahve some links, I'd love to see them; contact me outside of this discussion? My e-mail's on my profile. \$\endgroup\$
    – dwwilson66
    Commented Dec 23, 2013 at 14:28
  • \$\begingroup\$ Unfortunately, the simple version -- basically just a balanced, spinning mass -- probably won't be smaller by much, if at all. But at the very least, it won't require 50 ft ribbon cables. :) And i imagine all it takes is that aforementioned balanced mass (say, the platters and such from the hard drives) and a decent motor. \$\endgroup\$
    – cHao
    Commented Dec 25, 2013 at 3:56

1 Answer 1


This connector is called Single Connector Attachment (SCA): Wikipedia page. This should help you find a pinout.

Also, AFAIK, ALL disk drives require the controller electronics to be powered to spin up a drive. Powering the motor alone will not spin up the drive. Also, I wouldn't guarantee that if powered but with no host communications, the controller wouldn't eventually spin gown the drive.


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