12 Volt power from a Computer CPU?

[Jaffa007]

Hi All,

Is an idea for a project. Does anybody have any links? Or if you've made one yourself, possibly post links or pics?

Thanks

James

[Ant]

I suppose you could break into the power lead and then use Diodes to bring the voltage down to 12vdc. I beleive that a Diode reduces the voltage by 0.7. So if the laptop has a 18vdc supply then you could add 8 diodes to bring the voltage down to 12.4.

Not sure if that's what you mean.

Please do not attempt this without knowing what your doing - I wouldn't!

Ant

[geppetto]

I'll assume that you mean a desktop PC internal PSU?

If you have no experience in electronics then leave well alone......

If you have then yes, one of those could be made into a source of 12 volts

but you would have to work out how to replace the soft start switch that you have

on the front of computers and the other supply lines might need to be loaded for the PSU to

operate correctly....

Not really worth doing to be honest

[Jaffa007]

I do have a little knowledge of electrics, but as always, safety first [ask before you touch ]. But know where near the knowhow you obviously have Ant :salute: 8)

Yes Phil, a computers CPU. Remember reading about it on net. Also that one of the plugs from them have a 12 volt line out. But as you say the start switch etc would need to configured also. This is starting to sound a bit out of my legaue

Thanks for the advice anyway guys.

James

[Ant]

I can wire a plug. solder wires together that's it.

I just happen to know that Diodes reduce voltage. I doubt that I could actually get it to work - which is why I added to my post that I wouldn't do it.

Ant

[geppetto]

I do have a little knowledge of electrics

This is the problem mate...

I have 40 years as an all things electronic service engineer behind me and am loathed

to advise folk on such DIY projects that involve high voltages...

Sorry to sound negative but save up and buy something suitable, we don't want to loose you

[Macavity]

You don't want/need to go ANYWHERE near the CPU.

But is is perfectly conventional e.g. to install extra 12V Fans in any Desktop Computer. There are e.g. standard leads and connectors which take off e.g. +12V, +5V and 0V, via "Molex"(?) connectors that can be used to extends the cables that emerge from the PSU and chain to the floppy, CD/DVD, HD etc. Perhaps the best choice would be to split one of the less-critical leads to a CD Drive. I think anyone with a modicum of electronic knowledge, soldering experience, voltmeter, common sense etc. MIGHT contemplate this.

Remeber though that most fans consume WELL below 10W and it might be a good idea to check the voltages aren't being "flattened" by your little "addition". (There's usually some sort of software voltage monitoring program). It might be tempting to connect to Motherboard fan connectors - Possible still, but IIRC, they are only rated for 6W or so. Best AVOIDED - You don't want to fry some of the copper tracks on the Mobo.

This is the SORT of thing you MIGHT use. A local PC dealer might be of help...

http://www.maplin.co.uk/Module.aspx?ModuleNo=10951&&source=14&doy=Search

http://www.maplin.co.uk/Module.aspx?ModuleNo=32406&&source=14&doy=Search

etc. etc.

Yellow lead is +12V, Red +5V, Black OV (common). You might also consider WHAT you are connecting to the PC - Computer type "Electronics" might be O.K., but you don't wanna introduce all kinds of "cr*p" (noise) onto your PC power lines! Again, If you don't feel confident (competent) though, better to desist! No shame involved

[geppetto]

You don't want/need to go ANYWHERE near the CPU.

Might have missunderstood this as I thought he was on about buying or using an existing

stand alone computer PSU to maybe power his scope or whatever......

Be interesting to hear it sizzle when the dew gets on the PCB :shock

My advice still stands, go buy one instead

[Macavity]

True enough. Computer Power supplies are designed to work best inside a PC... inside an office, your bedroom etc., rather than (like astronomers) on the "blasted heath" etc.

(May have got Overexcited)

[Jaffa007]

Thankyou all & sorry for my original VAGUE question.

Mc, that was where my thought was going, Molex leads, and it was with the intention of possibly powering the scope. I wouldn't of connected it to anything unless I was 110% happy with it.

I will now heed your words of wisdom & get my coat........ TAXI

P.S. Thanks again all.

[Akyra]

It is soooo easy to power up a standard desktop CPU, just attach a short length of cable between the green and black cable in the white motherboard connector and it powers up, then just tap off the yellow cable (+12v) and the black cable (-12v) (the red cable is +5v) of a HDD/CDDRIVE molex connector. It is safe as long as all cabling is secure, .ie do not shove the cables in the ends of the molex connector - speaking from experience here folks!

I used this setup for testing and construction when building my CarPC for the Focus.

[peonic]

It is soooo easy to power up a standard desktop CPU, just attach a short length of cable between the green and black cable and its powers up, then just tap off the yellow cables (+12v) and the black earths (-12v), the red cables are +5v

Not being funny Akyra - but instructions that vague are liable to lead to someone blowing something up....

Chris

[Akyra]

Not being funny Akyra - but instructions that vague are liable to lead to someone blowing something up....

Chris

Well, thats just how easy it is I'm sorry. If the CPU isnt wired up correctly it will shutdown automatticly and will require unplugging/switching on&off to restart, so no BLOWING UP sorry Chris

[Akyra]

Powering Up A PSU Without A Motherboard - Pictures of what I described above....

But if your PSU has a switch on the back then you dont need to put another switch in, unless it is more convenient of course. But do make sure cable is secure otherwise it'll do your nut

Then simply cut off the molex connector (obviously while power cable is unplugged! :shock:) then connect your 12v accessory to the cables :

Yellow = +12V

Black = -12V

Red & Other Black = +5V & -12V (Both can be cut off and sealed with wiretape, etc.)

[peonic]

That's closer.

Your original post contained no hint as to WHICH red / green / yellow cables you were talking about - as someone who's spent most of the last 15 years taking PC's to bits for work and pleasure, I've taken a few belts from PSU's - it tends to make you clench your teeth a bit.

Cheers,

Chris

[Jamie]

Well, thats just how easy it is I'm sorry. If the CPU isnt wired up correctly it will shutdown automatticly and will require unplugging/switching on&off to restart, so no BLOWING UP sorry Chris

Akyra it might be that easy to you but not to those that don't have the know how.

So a little less of the arrogant cocky answers if you please... :nono:

[Akyra]

EDIT : I have editted my first post now to to reflect a few 'key' pointers :(

I've never been zapped by a PSU, but have had plenty of 12volt from my car through my teeth when biting the wire to strip it, not realising it was live! Terrible habit I know but I dont have wire strippers

[geppetto]

Don't really understand where this is going but as a person who is fully qualified to advise

on this sort of thing, I would urge people to think hard about the safety issues here.

Switched mode power supplies can be killers at worst and should be treated with respect.

These PSU's are designed to be used indoors in a computer case with no access to the internals.

To say that a PSU will shutdown if it detects an overload or wrongly connected cable is foolish.

They are indeed designed not to go overvolts or overcurrent but these safety features can and do

fail believe me...

Saving a few pounds by risking your health seems very strange to me.

Akyra

I would hate to insult you and so if you have electronics qualifications then fine but if not

then you should not really be advising people about these things.. :nono:

[Akyra]

The actual PSU innards are not exposed, only the cables which if securely connected in the proper fashion should not harm the equipment nor the individual.

I do not have electronics qualifications, I was merely adding my experience to this discussion as it is a solution for the asked question.

If you feel it is inappropriate then please do remove all my postings. But I feel that as long as you take my cautions into account when doing this mod that all should be well.

[geppetto]

I do not have electronics qualifications

There you go then....

No need to remove your posts mate, it a fair disscusion about an important

issue.

Only thing I would suggest is that you make sure that when you advise people

about this sort of thing, you let them know that your not qualified so they dont

think otherwise and end up killing themselves

[Akyra]

I do not have electronics qualifications

There you go then....

Hey! I just got told off being cocky! :nono:

[geppetto]

Hey! I just got told off being cocky!

I'll probably get told off as well :sad5:

[Jamie]

[Kaptain Klevtsov]

I'd always go for a proper power supply like Maplins sell for cheap. The stuff that you're powering could be a goto system that would cost hundreds or more to replace if you fried it by putting the wrong flavour power up it. The saving is so small that its not worth the risk. You'd probably have to buy a box to put the PC PSU in to stop stuff falling in the holes and making it go bang, and that would need ventilation as well.

Too much hassle for me.

Kaptain Klevtsov

[beamish]

well said KK, for a few quid for pitty's sake stay safe. It'll probably be far more convenient in the long run too. It certainly limits the damage if things go wrong with one component too.