DIY power supply for HDDs

Hi there,

I'm thinking of making my own external harddisk to keep on my desk. You know: for backups, etc.

I'm (probably) going to fit 2 HDDs in there. The HDDs need both 12V and 5V and since I don't want to connect two adapters to it I need to change the 12V that goes into the box to 5V. I've done some research and I think I got it figured out... I think a 78s05 condensator should do the trick.

Side note: the disks need 0.9A and 0.72A on 5V (=1.62A).

I've attached a picture where I show my idea.... any thoughts and most of all WOULD THIS WORK?

Kind regards,


Picture of DIY power supply for HDDs
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Niellles (author) 5 years ago
Thanks for all the answers. I probably know enough for now. I'll probably take some photographs and write an instructable when I'm finished.
Niellles (author) 5 years ago
I opened up an old power supply for a desktop computer and found some stuff that might be useful...

Will a heatsink as shown in the attached picture be enough? I'll put the fan on the back of the whole thing - because it looks cool and it will probably cool the stuff down!

Can I just screw the heatsink onto  a piece of wood or will that get too hot for the wood? (Suggestion on how to attach the heatsink are very welcome...)

Cheers and thanks for the help,

That heatsink should be OK. You don't need the insulator with the 7805, since the tab is at zero volts
Without a heatsink, it'll shut down in seconds - 100C/ 212F kind of thing.

You'll need some kind of sinking however you split things. Try your small sink and see what happens, by applying the power and testing it with your fingers.
Yes, it'll work. Make sure you have a good heatsink for the regulator, because its going to waste aroun 4W as heat.