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Off-board PC PSU

Discussion in 'Home Cinema Building DIY' started by ReTrO, Feb 28, 2003.

  1. ReTrO

    ReTrO
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    Does anyone know if off-board toroidal power supplies are available for PC's?

    I just sat through a lecture on power electronics and spent most of the time thinking about if it would be possible to modify a hifi power supply, such as those made by Naim and Cyrus, to supply power for a PC.

    The benefits would be that it is silnet and probably cleaner than a standard switch-mode jobbie in a PC. Wouldn't be cheap but may be worth doing on a one off project.

    Cheers for any stuff.:smashin:
     
  2. ReTrO

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    Someone must have sopme suggestions or owt.

    Cheers
     
  3. buns

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    I've not heard of any...... but i dont know that much!

    What are you going and giving your ideas away for anyhow!? Go and make one and i'll buy one of you! :D

    ad
     
  4. ReTrO

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    I've not got the knowledge yet to actually make one of these things. Might look into it over the summer time, I'll start discecting a spare ATX PSU at easter.

    I think my first off-board PSu will simply be the spare 300W ATX jobbie in a hifi sized case (may have to be an old Naim case or summit though, depend what I can find). That way at least i'll probably be able to dispose of the fans and make it silent, whack a mother of a heatsink on it.

    Ideally a power-amp case would be best, plain frontage and probably equipped with some sort of built-in heat sinking.

    I'll get my books on power supplies out next, I've only made a basic 5-15V linear regulated jobbie so far. Nowt special, part of the degree I'm doing.

    I have seen basic in-line switch mode PSU's (external style for laptops etc) which have sperate DC convertors that go inasicde the PC. That would allow a simple 12V PSU and then the rest is done inside. Only problem is I've only seen 55w versions max, I'll be requiring around 400-500w (it's gotta be future proof).

    (I wonder how much a new Naim PS would cost..., probably too much work in that though.)

    All above Copyright Rik. 2003 ;)
     
  5. ReTrO

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    All seems to be coming together well at the moment.

    I'm going to off-board my spare ATX PSU. Put it into a nice hifi case and run a custom 12 pin power cable from it to my PC. The PC will be fitted with the PSU metal box (for ease of fitting) with the necessary cables coming out.

    I've got a large heat-pipe heatsink for my GF4 Ti4400 coming so then I'll have a totally silnet PC.

    I'll be able to listen to Classic FM quietly at night with no disturbance.

    Bliss....

    :clap:
     
  6. BK Electronics

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    Hi There

    Ithink you only need 12V and 5 amp regulated, and i'm sure this is easily done.

    Just a few thoughts on the subject.

    The PSU is going to be large, the 5v rail needs something like 25A doesn't it?. (i'm not up on PC PSU's). Conventional PSU's have a refresh rate as it were of only 100Hz whereby a Switch mode is in the 10's of Kilohertz (50 to 150Khz). The switch mode can also track the mains input so if it drops it can still ouput exactly the same voltage and have PFC.

    Mind you a good regulated psu is easy to build, just mind those mains harmonics.

    Very interesting project. Keep us posted
     
  7. ReTrO

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    When I get around to building the toroidal PSU I'll be using a decent 500va transformer. It'll need a 240v primary and +12v, +3.3v and +5v windings on the secondary i suspect. I'll know more when I get into it.

    I'll see if I can speak to any of the guys at Naim for tips etc, thwey should know a fair bit.

    In the mean time if I can shut-up and cool my current switch-mode ATX PSU then I'll be very happy.

    :smashin:
     
  8. Mark Grant

    Mark Grant
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    Hello Retro,

    I looked into this a year or two ago, I had a plan to make a nice and smooth off board PC PSU and maybe sell some.

    The problem with selling anything electrical that you manufacture yourself is the CE marking. Expensive, and if someone complains about a product and it is found to be not CE marked, you are in Deep *hit.

    I have seen a small off board PSU on a Japanese website once, was only low power though, cannot find the link at the moment.
    It was switched mode looking at the size of it.


    I would probably use seperate transformers for the voltages you require, rather than a multi tapped transformer.
    Don't forget the -5V and -12V.

    You would need to build the thing to supply as much power as at least a 400W switch mode PSU, no good having the PSU running at full load.

    I would make a blanking plate that has a large multipole power connector that fits in place of the PSU in the HTPC.

    The off board PSU could be mounted in a decent looking desktop PC case, again with a blanking plate in place of the PSU, with multipole connector, then a large multicore cable to link power to HTPC. Maybe caravan/trailer cable for the prototype, if enough curent capacity.

    Find some good voltage regulators, do some research on big capacitors to smooth the DC supply on each PSU rail, and you could have a nice and smooth PSU.

    Test your PSU on an old PC first, don't blow up your pride and joy HTPC :rolleyes:

    Good luck with the project,

    Mark.
     
  9. ReTrO

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    I'll be testing it all on a spare PII based machine, it's got onboard grpahics etc so all it needs is a PSU and you can pretty much test everything with a HDD or RAM etc.

    I shan't be selling any until everything worked perfectly, it'll probably not get past the one off project unlees there was any demand at all.
     
  10. Mark Grant

    Mark Grant
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  11. ReTrO

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    Cheers Mark.
     
  12. ReTrO

    ReTrO
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    All ideas are going well, just need a case/box to put the bits in.

    If anyone has an old non-working power-amp box or similar with decent sized internal or external heatsinks could they please contact me.

    Cheers!
     
  13. ReTrO

    ReTrO
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    Just been fidling with my PSU, seems ok so far, I'm still here!

    I reversed the fan to blow onto the heatsinks of the transistors, keeps the fan speed down so that it very quiet. It's no louder than my Papst and QuietPC case and CPU fans now. Can't wait to get it into a bigger case with better cooling.
     
  14. tomson

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    Retro - where did you buy your Papst fans from?
     
  15. ReTrO

    ReTrO
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    I bought the Papst fan from QuietPC.com . I dare say there are many other suppliers.
     
  16. Taz

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    Not a hijack just need a quick answer;) and you seem to be up on this Rick..

    In what order would i go about making my pc quieter then? its using bog standard power supply/fans at the mo.

    Cheers
     
  17. ReTrO

    ReTrO
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    No problemo.

    Main noise culprits are:

    CPU Fan
    GPU Fan
    High speed optical drives
    HDD (loud ones)
    PSU Fan
    Northbridge Fan
    HDD (good ones)

    Replacements can be had for all these parts:

    CPU - various quiet options, quietest I know are the Zlamn flowers. Used with the 92mm fan these can barely be heard.

    GPU - Again Zlamn make 2 options here, a basic fans less heatsink for older less powerful cards and a large heatpipe cooler for newer GF3/4 cards etc.

    Optical drives - try to find a speed controller, not sure of any other options yet (though this is something I am going to investigate in the future).

    HDD - Get a Seagate Barracuda if yours is overly loud (most likely not)

    PSU Fan - These can be replaced, or you can re-place the whole PSu, which costs more but is probably much safer than fidling with the PSU.

    Northbridge chipset fan - can be replaced by a Zalman northbridge chipset for silent cooling.

    Think that's it all.

    QuietPC.com or Dabs.com have pretty much all the bits to do this. They have supplied all my extra parts.
     
  18. ReTrO

    ReTrO
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    Work is progressing on the off-board PC PSU.

    I had a mess around with the connectors I bought before easter and am pleased with them, though I have been looking for something with less pins to carry the high current power cables (as opposed to the signal ones in the ATX spec.).

    I have now found a suitable connector at Maplin, which has 8 pins and will do the job well, it is also not too expensive and take high gauge wire.

    See here for the plug:

    http://www.maplin.co.uk/products/module.asp?CartID=030427011041392&moduleno=1386&modulecode=

    and here for the socket:

    http://www.maplin.co.uk/products/module.asp?CartID=030427011041392&moduleno=1387&modulecode=

    I hope to get this all up and working at the start of the summer.

    All I need now is a box to put it in. I hope to make one from MDF, that will be approxiamtely half the size of a standard hifi box (say around 120x220x300 mm (hxwxd)), such that it will not look out of place with the rest of my system. This will be painted balck at some point to also help blend in.

    It should have a power on indicator LED on the front, and some sort of internal shielding to help cut down on EMI and RFI emissions, that will interfere with my radio tuner etc.

    It will be fitted with 2 fans running off the internal heat speed controller already fitted, an intake fan at the front and an outtake fan at the back. This should keep the heat down to a very low level, as well as fan noise, which is my main consideration. There will be an extra 12mm front panel in front of the intake fan to help keep any sound in, with a decent gap behind to not prevent air flow for the fan.

    I'll keep this updated as and when bits get done. I've just ordered the new power plugs and sockets from Maplin.
     
  19. Taz

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    UH OH!:eek:


    or roughly translated.... "I'm gonna make Taz do it!"

    :D
     
  20. ReTrO

    ReTrO
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    Maybe, maybe not. It should be fairly simple, maybe you could cut them for me...:laugh:
     
  21. Taz

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    I knew it! :rotfl:


    send me cutting list :smoke:
     
  22. ReTrO

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    Heh heh. You cna give me some help with the box Mr Taz, but I'll not ask you to supply the parts to make your life easier.

    The power plugs and sockets arrived today, they appear to be more than upto the job. They handle 5A at 240V so they are more than adaquet, just need some placti braiding to hold all the cables together now.

    Who can tell me where to get this from?

    I only need a couple of meters of the stuff.

    Cheers guys.
     
  23. RichardH

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  24. ReTrO

    ReTrO
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    Sounds good.

    What diametre stuff are you looking at?
     
  25. RichardH

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    You pick what you want. I wasn't getting any for myself, just ordering other bits. Might get some to wrap the TNT snakes though, in which case it would be around the 25mm expanded size.
     
  26. ReTrO

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    Sounds about right to me.

    The max it will need to carry is 8 1.5mm cables.
     
  27. RichardH

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    What, 8 single 1.5mm2 cables? Just done a test with 3 3 core 1.5mm2 cables (so 9 1.5mm2 cables in total), all in their outer sheathing still, and they went into a 19mm diameter tube.

    I assume shrinkwrap would be too "tight" for this - you just want a loose flexible container for the cables?
     
  28. ReTrO

    ReTrO
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    Yep, that's right.

    I don't want to use shrink wrap as it's not quite flexible enough, and you get creases in it when you bend it.
     
  29. RichardH

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    Just confimr which diameter you want, and I'll add some to the order.
    R
     
  30. ReTrO

    ReTrO
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    Best go with 19mm then. :D
     

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