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Have a way to get 17 V from an PC psu? Answered

I need 17 V for a project, I have a few of old PC psus that delivers the common 5V and 12 V. Have a way to get 17V from it? I'm a newbie in electronics, a weblink with pictures is welcome. Thanks

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NatureTMBest Answer (author)2009-12-21

yeah you can get 17!!!!!!!!!!
there's usually +12, +5, +3.3, Gnd, and -5 (all in volts) outputsof a psu.  I think the -5 is on the mobo plug (use a multimeter or read about the connector).  Use -5 as ground and +12 as positive.  Voila!  A 17V differential.  Check your psu's ratings to be sure you won't be drawing too much current.  The -5 might only allow a couple amps.  I converted a computer psu to a workbench psu and this does work.  You could even use -5 as negative and gnd as positive for 5 volts if you wanted.  The thing that matters is the difference.  Watch those amps though!  Like I said, -5 might only allow a little.

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saturnino (author)NatureTM2010-05-14

Each time I connect +/- 5 to -/+ 12 terminals, power goes off. How to connect ?

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lzf (author)saturnino2010-08-28
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AngelLaHash (author)saturnino2010-06-14

just need some thing better them Cap/resistor.. but how to get the sum of them than one taking from the other

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pkveazey (author)2012-02-26

A computer power supply is a switching supply. Basically it takes the 120 volts AC from the wall and turns it on and off really fast. That's why its called a switching supply. Before it has an opportunity to reach 120 volts, it turns off at the desired voltage. Then its converted to DC If you can find a way to put a variable resistor in the supply. You can dial up whatever ON/OFF frequency you want, therefore, dialing up whatever voltage you want. You probably can get it way up near 120. I've never been able to figure out how to turn the power supply on with the power supply out of the computer. The ON/OFF switch on the computer momentarily makes contact and spikes the power supply which turns on the 12 volts. Every time I check the voltage of a Computer supply outside of the computer, all I read is the 5 volts. It always shows no voltage on the 12 volt lead. That's because I haven't turned on the 12 volts. If somebody has figured out how to turn on the supply, while outside the computer, please let me know.

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lzf (author)2010-08-28

the hightest u car get out of a pc psu is 24V -12 and +12

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warengadia (author)2010-08-25

you have to use a 5 ,3v lithium battery and 1v battery because is equal to 17v and portable battery because is to small battery and you insert in psu computer. and so can support the need of your PC psu and that is my answer.

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lemonie (author)2009-06-17

Why 17V - can you not manage with 12? L

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AngelLaHash (author)lemonie2010-06-13

if they need 17 then they need 17 .. personaly i need 15 normaly a amp that needs the max you can

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lemonie (author)AngelLaHash2010-06-14


I didn't see "amp" mentioned, do you know this guy?

L

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AngelLaHash (author)2010-06-14

IM using a summing amp... 12v as the V+ and Earth as the -V 12v hooked up to a 1k then on the - input 5v hooked up to 1k and then the - input the + input is earthed as bridge resistor between the - input and the output of 1k

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AngelLaHash (author)AngelLaHash2010-06-14

only gave me a output of -8 shouldnt it be Vo = Rf((V1/R1)+(V2/R2)) so Rf = 1k ... V1 = 12v ... R1 = 1k ... V2 = 5v ... R2 = 1k Vo = 1'000((12/1'000)+(5/1'000)) Vo = 1'000( 0.012 + 0.005 ) Vo = 1'000 x 0.017 Vo = 17v

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AngelLaHash (author)2010-06-13

For me i didnt edit a PSU.. i just got a light switch .. put in a ATX connection and wired it up to the switch and out 5v and 12v as well as earth with its -12v and -5 counter parts.. ive been reading people moaning that its not 5v or 12v .. what the hell is perfection in electronics .. all resistors have a 5% or less tol what can be way out in the end

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KnoBall (author)2009-06-17

Unfortunately the minimum that I need is 15V. I`m thinking if have a way to make some kind of series link with those 5V and 12V wires.

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Joe Martin (author)2009-06-17

The highest voltage a PSU gives out is 12V

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