What voltages to hard drives use?

[Shaftatplanetquake]

I'm talking IDE here (don't think that would make a difference, but I'll specify)

I'm sure it uses ground, and but not sure if it uses 5V, 12V, or both?

Thanks

 

[highwire]

Not sure if there isn't more to the question, but all hard drives I know of use the +5V for the logic and the +12V for the mechanisms - motor and heads. That goes for floppies as well.

 

[Shaftatplanetquake]

Thanks, that was exactly what I was looking for.

 

[Shaftatplanetquake]

Actually, 1 more question. Do you have to send the ground wire from a power supply to a hard drive to get it to work?

 

[highwire]

Just to be sure, I checked an old WD 4Gig drive's power connections.

The 2 ground pins are tied together hard at the circuit board as well as chassis ground.

So this unit COULD be operated using the chassis ground only and just the 2 power connections, though that is not good practice.

It might even damage something if the ground is accidentally lifted and the data cable becomes some the only grounding conection.

 

[Evadman]

It might even damage something if the ground is accidentally lifted and the data cable becomes the only grounding conection.

It would at least toast the cable. 2+ amps on a 28 gauge wire will fry the insulation off in about a minute if you are lucky.

 

[highwire]

Evadman-

As you know, there are a few 28awg ground wires in the data cable, so it might take a while. But, still bad.

 

[SCSIRAID]

Trying to use the data cable for DC ground is not a good idea. All the impulse noise from the drive operations will couple onto the IDE bus and will likely make a mess of your signal quality. Additionally you are passing all the drives DC return current thru the motherboard instead of directly to the power supply. This makes for more I2R loss during transients (seek) etc.