| ecman |
I wonder if there is a way to use a PC PSU modded/or non-modded ?
Would it be better to had somthing on the amp board or to mod the PSU ?
Or even just use and reassemble some parts found in it ? |
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| ir |
short answer: no
long answer: yes, of course. BUT...
you will need a: an oscilliscope - this is non-optional. b: a LOT of patience. c: a reasonably high IQ and the smarts to know what's safe to do and what's going to cause a fire and d: some tools, a soldering iron etc
now that you know it's possible it's up to you. if you can't work it out, then it's probably best you don't. |
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| theChris |
the ATX case might be useful to store parts in. it has a place for a plug built in...
now sure how you'd fit a transformer and heatsink in as well, but i'm sure it's possible. |
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| Hybrid fourdoor |
I think he means, can you use it to power the chips...right?
Well at the heart of it, it seems cool. I mean 12V at like 8-10A. But the -12V is very low, so you would have to make one of those fake negative voltages (like referencing the +12V and turning it into -12V).
I think most poeple will say the noise is too high, although the National chips are known for the there ripple rejection...plus would a choke help here? Actually don't most PC PSU's have chokes in them already?
Either way its tempting seeing a big PSU thats only like $30. Although 12V is low, a series/parrellel chip combo would give you increased output. |
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| MWP |
Erm, i think you kinda missed the point of this thread. |
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| Elso Kwak |
Hi,
I would not mess up with a switched mode powersupply. If if it works OK. If it breaks down, trash it!
Besides that you cannnot imagine how much noise this kind of supply generates.:bigeyes: |
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| gmarsh |
It's possible...
You'll have to tear out the rectification/output side of the supply, and remove and rewind the main transformer to have two output windings sized for 20 something volts instead of 5V/12V/etc. Maybe even another winding to power the control circuitry used. Then you'll need to put in new output caps, new rectifiers and new output inductors, and you'll have to invent a new feedback/control loop for the supply so that it's stable and putting out the correct volts.
With enough filtering and attention to detail, you can make a very clean switching power supply. Making such a supply out of a computer supply isn't going to be easy, though.. |
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| carlmart |
Once I had an idea to build an external linear power supply for my PC, as at least the internal environment would be free of RFI. The switching design is very bad for audio, at least at such low pricing.
Has anyone tried such a thing? Is it worth it?
Carlos |
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| MWP |
| quote: | Originally posted by carlmart
Once I had an idea to build an external linear power supply for my PC, as at least the internal environment would be free of RFI. The switching design is very bad for audio, at least at such low pricing.
Has anyone tried such a thing? Is it worth it?
Carlos |
Not for the PC its not worth trying.
Even though the power source may be smooth, the switch-mode psu's on the motherboard and other hardware will chop it up quite badly.
Best you can do is only supply the soundcard with a decent linear power source (cut it off from the PCI power source). |
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| Tsanford |
I think he was talking about powering the whole PC from a linear power supply.
I too would like to try a linear power supply for an audio PC, Anyone know where to get the pinouts of the standard power supply connector and current draws mabye?
I may hook up a PC to my system if I could get that noise supply, I mean power supply out of there dont even want one near my other gear. |
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| Overd0se |
| quote: | | I too would like to try a linear power supply for an audio PC, Anyone know where to get the pinouts of the standard power supply connector and current draws mabye? |
Current draw will be dependent on your hardware. Look at the outputs on some good quality PSUs for reference. The connector pinout will be in almost any motherboard book. I hope the diagrams make sense. :D
PIN out by number| PHP: |
1 +3.3V 11 +3.3V
2 +3.3V 12 -12V
3 Ground 13 Ground
4 +5V 14 Power Supply On
5 Ground 15 Ground
6 +5V 16 Ground
7 Ground 17 Ground
8 Power Good 18 -5V
9 +5V 19 +5V
10 +12V 20 +5V
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ATX connector (socket)| PHP: |
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| Optical |
Yes, i have sucessfully modded a pc power supply for use with amplifiers, the directions are given in silicon chip magazine sept 2003 and another similar article july 2004.
I have only had the time to mod one so farbut it works great, it basically involves taking out the switching transformer, rewinding it for a new voltage you want and using a voltage divider back to the voltage sensor to keep it thinking its at 12V
get those articles if you can. |
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| jackinnj |
if you have to use a PC supply:
it can be done, but it is much simpler to use the outputs "as-is" and then use the high current outputs to drive a flyback-boost inverter and a flyback-boost-converter --
noisy, but it will work. |
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| gmarsh |
| quote: | Originally posted by carlmart
Once I had an idea to build an external linear power supply for my PC, as at least the internal environment would be free of RFI. The switching design is very bad for audio, at least at such low pricing.
Has anyone tried such a thing? Is it worth it?
Carlos |
I doubt it... most of the RFI generated inside a computer is from high frequency clocks going around the motherboard, hard drive actuators and other things, not the power supply itself. Even with a linear power supply, your computer and its peripherals will quickly throw noise on the power supply rails.
If you want better quality from your soundcard, you'll pretty much have to modify the soundcard itself. |
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| carlosfm |
| quote: | Originally posted by gmarsh
If you want better quality from your soundcard, you'll pretty much have to modify the soundcard itself. |
That's what I have.
I have a +/-15v linear PSU for the soundcard (actually, only for the op-amps, OPA2604s instead of the dreadful original TLO72s).
It's a humble old SB Live Value.
Better would be to power all the soundcard from external PSUs, but this one is not worth the trouble.
If you want good sound on your PC, you need at least a decent external soundcard.
Then, tweak it.:D |
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| Stocker |
| quote: | Originally posted by MWP
Not for the PC its not worth trying.
Even though the power source may be smooth, the switch-mode psu's on the motherboard and other hardware will chop it up quite badly.
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You could always find what voltages are being generated where, locally, on the motherboard, and make linear regulators for all of them, too...
:xeye:
Sounds (!) like a hassle to me. |
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| ecman |
| quote: | Originally posted by Optical
Yes, i have sucessfully modded a pc power supply for use with amplifiers, the directions are given in silicon chip magazine sept 2003 and another similar article july 2004.
I have only had the time to mod one so farbut it works great, it basically involves taking out the switching transformer, rewinding it for a new voltage you want and using a voltage divider back to the voltage sensor to keep it thinking its at 12V
get those articles if you can. |
Is it this article you are talking about ?
http://www.siliconchip.com.au/cms/A_102096/article.html
I don 't know yet how to take advantage of these.
A PC PSU can provide a strong +12 V but a weak -12 V.
Well maybe i must search for a chip that can feed with only one +12 V rail rather than moding the PSU.
Maybe an op amp for car audio. Cars bateries have (0,+12V)
Though the PSU obviously has the capacity to provide much various voltages, i don't see any simple way to have a symetrical one. |
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| Optical |
Yes thats the July 04 article, the October 03 article is better..
http://www.siliconchip.com.au/cms/A_30705/article.html
The +/-12V and 5V outputs are scrapped to make way for a new winding which is centertapped, so essentially you can wind on any voltage you like which the total power remaining at 200W (pr whatever), so you can work out the current draw you would expect for the voltage you want..
Once you have wound yourself the new transformer you put a voltage divider on teh output and take a tap of 12V to send back to the voltage sensor :)
the transformer winding process is the trickiest bit, the article explain it all very well though.. i would scan teh pages but i dont have a scanner :( |
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| ir |
right, now that my forums are back up, here be a link
a friend of mine built an LM4766 amp completely inside and powered by a standard PC power supply
the amp runs at +/-28V. obtaining this is fairly easy, you simply remove the 5V regulator which provies feedback to teh switching controller. Once you do this, the controller has no reference to verify that it's producing the correct voltages. As a result, it ups the switching frequency and therefore the voltage
http://oc4free.scalded.net/forum/vi...ht=power+supply
again tho, you will need an osciliscope. and this project is NOT for beginners - the potential for catastrophic failure of the SMPS is very high if you don't know what you're doing - also worth a note, some parts are running at 320V DC so watch what you mess with |
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