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Is it possible to power a HDD without a desktop PSU ?

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Go to solution Solved by Needfuldoer,

No reason that shouldn't work.

 

You could also combine an off-the-shelf 4 pin Molex AC adapter with a Molex to SATA power adapter for the same result.

 

https://www.amazon.com/Coolerguys-100-240v-Molex-Power-Adapter/dp/B000MGG6SC/

https://www.amazon.com/Monoprice-108794-24-Inch-15-Pin-Female/dp/B009GULFJ0

This is just something I've been thinking about. Just a small DIY project I want to do. Nothing serious.

I will try to keep this short. I'm making a server out of my old laptop. The HDD in the laptop is failing. I want to use one of my desktop hard drive. The full 3.5" HDD obviously requires a 12V + 5V power supply.

I want to keep it a really low powered build so adding a complete desktop power supply seems like a step in the opposite direction. I don't want to use SATA to USB since the HDD will hold all the data and will be the boot drive too.

 

So here's what I have thought about just out of curiosity.

I have a lot of DC 12V adapters from old routers and stuff. Can't I just use a 12V to 5V step down converter for the 5V wire ? I made this crude sketch in paint to show what I'm trying to do.

 

Untitled.png.8ade93492eec141bcab0aece01e4e581.png

 

I *think* this should "theoretically" work.

What kind of challenges or problems you guys think I will face ? I'll be making the stepdown converter myself so the current shouldn't be a problem (i wish).

 

I'm not really good at electronics anyway. My brother is but he won't be home for a few days.

 

Thanks ~!

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yes, there's nothing magical with the PSU cables, it's just a regular 5v.

so when you plug any 5v power source, the hdd will turn on.

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Yes, just clip 5/12/gnd where they go.

I'm not a professional, just an enthusiast. I don't know everything.

HGST Ultrastar: The last HDD you'll ever need to buy (and the one I always recommend).

Schrödinger's CPU: The Q9650. Is it irrelevant? Is it not? 

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7 minutes ago, RONOTHAN## said:

Thanks for the confirmation ! I don't want to use any USB solutions for multiple reasons. Also, I want to DIY this one 😄 Thanks !

6 minutes ago, Needfuldoer said:

No reason that shouldn't work.

 

You could also combine an off-the-shelf 4 pin Molex AC adapter with a Molex to SATA power adapter for the same result.

 

https://www.amazon.com/Coolerguys-100-240v-Molex-Power-Adapter/dp/B000MGG6SC/

https://www.amazon.com/Monoprice-108794-24-Inch-15-Pin-Female/dp/B009GULFJ0

Nice. Thanks. I want to make this one myself. I like making stuff like this and I most probably have all the stuff I will need to make this one.

 

Thanks a lot everyone for the confirmation. I'll make my server and post it here ! 😄 Thanks again !

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Grounding might be a thing to consider here, as the HDD and the Laptop board have different PSUs. Don't ask me any specific things though because it was just a thought I had while thinking about your idea.

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Laptop SATA drives use only 5v. You also have a lot of 5v sources, for example the USB connectors.

 

You can buy or you can make a 5v to 12v step-up regulator / dc-dc converter and boost 5v from the sata power connector on the laptop or from usb ports to 12v.

 

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2 minutes ago, mariushm said:

Laptop SATA drives use only 5v. You also have a lot of 5v sources, for example the USB connectors.

 

You can buy or you can make a 5v to 12v step-up regulator / dc-dc converter and boost 5v from the sata power connector on the laptop or from usb ports to 12v.

 

This might be something I will look into. Can it fry the USB port or controller tho ?

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Well, a desktop mechanical drive will consume around 6-8 watts in total, and will take around 3w of that on 5v (for the circuit board, chips on the pcb) and the rest of around 3-5 watts will be on 12v.

But, when the motor starts, the drive will take a bit more power, let's say maybe a couple watts more so let's say 8-10w for a few seconds.

So basically 10w on 12v should be enough.  To produce 10w on 12v from 5v, you'd need around 11w on 5v due to conversion efficiency losses.

 

The laptop will probably be capped at around 1.5-2A on 5v on the sata power connector, I doubt the voltage regulator will be capable of more... so you can't really produce 10w on 12v from just the sata power connector on your laptop.

usb 3.0 ports will output at least 1A each ... so you could take 5v from two such usb connectors and get your 10w

 

If you're gonna power the laptop motherboard from laptop adapter, through a barrel jack, you have another option ... you could solder two wires to the barrel jack pins and get 16v...20v from there (whatever voltage is supplied by the laptop adapter).

You can then make a step-down / buck dc-dc converter to convert that voltage to 12v and you can enable the dc-dc converter with a signal from the 5v power from the sata power connector - this way the dc-dc converter only produces 12v when the laptop turns on and powers the circuit board on the drive.

 

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4 minutes ago, mariushm said:

If you're gonna power the laptop motherboard from laptop adapter, through a barrel jack, you have another option ... you could solder two wires to the barrel jack pins and get 16v...20v from there (whatever voltage is supplied by the laptop adapter).

You can then make a step-down / buck dc-dc converter to convert that voltage to 12v and you can enable the dc-dc converter with a signal from the 5v power from the sata power connector - this way the dc-dc converter only produces 12v when the laptop turns on and powers the circuit board on the drive

This really seems like the best possible option since I already have the laptop stripped down to the bare minimum. Also the idea to turn on the DC-DC converter using the signal from the 5V signal is just icing on the cake. Thanks a lot.

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