hard drives still use about the same 12v to spin the main motor. hard drives even the olds ones were not power hogs. if your taking about cd-rom drives they only use power to spin the cd roms and there low wattage drives.
Here is a repository of some very old technical manuals:
http://bitsavers.trailing-edge.com/pdf/
That link is amazing! So much computer history and info there. An almost 200 page parts catalog from Commodore! I will never be bored at work again with this.
There should be a badge we can hand out for making a moderator happy
I have about 50 manuals from the 1970s and 1980s that I will scan someday. It seems criminal to dump them without ensuring that they live on for posterity.