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PC Power Supply interface — Parallax Forums

PC Power Supply interface

Chip CoxChip Cox Posts: 73
edited 2010-02-11 01:02 in Propeller 1
I'm building a project and rather than try and build an enclosure with wall warts in it to power my propeller and RC4 boards, I was thinking about using the 3, 5 and 12v dc outputs from a PC power supply to power my boards.· As is usually the case, I'm sure there is something I'm not thinking about, or an easier way to do this.· So what do yall think?·

Comments

  • Mike GreenMike Green Posts: 23,101
    edited 2010-01-26 19:37
    There's usually a minimum load that has to be on the 5V supply for the PC power supply to regulate properly. Get a datasheet for the power supply you plan to use and look for this sort of information
  • Toby SeckshundToby Seckshund Posts: 2,027
    edited 2010-01-26 19:58
    With the minimum load sorted out, beware the power available. Hundreds of Watts can be swift, and brutal, so make good usage of fuses.

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  • Paul Sr.Paul Sr. Posts: 435
    edited 2010-01-26 19:58
    I have been using one as my bench supply for 2-3 years now and it has been great. Never an issue and the power has been rock solid.

    There are articles all over the net about how people have modified them for their needs. I didn't modify anything - just put a jumper in for the "on" signal in the motherboard connector and made various adapters to plug on to the standard 4 pin peripheral plugs. I have any of the output voltages available in whatever configuration I need them.
  • BergamotBergamot Posts: 185
    edited 2010-01-26 20:03
    Sparkfun has a breakout board for that:

    http://www.sparkfun.com/commerce/product_info.php?products_id=9558
  • Paul Sr.Paul Sr. Posts: 435
    edited 2010-01-26 20:07
    For $7.00, and still have to make the connectors, I'll take my cheap and dirty solution!!
  • Chip CoxChip Cox Posts: 73
    edited 2010-02-08 20:40
    What did you use to provide the 6-9 volts for the propeller??
  • AJMAJM Posts: 171
    edited 2010-02-08 21:27
    The propeller requires 3.3 volts.

    For a cheap solution, you can use a linear 3.3 voltage regulator off of a 5 volt rail.
  • Clock LoopClock Loop Posts: 2,069
    edited 2010-02-09 21:07
    3.3v.... Pc power supply. Atx?


    obex has an app for that. err wait..

    attachment.php?attachmentid=67592
    20 Pin ATX Pinout.gif
    539 x 360 - 12K
  • pmrobertpmrobert Posts: 677
    edited 2010-02-09 21:22
    As Mike pointed out previously, they seem to require at least some load to regulate properly. I've used anything from an old hard drive to an incandescent bulb to a 100 ohm resistor across the +5 to ground. They also don't like inductive flyback spikes from larger relays, ignition coils and the like. The spikes appear to temporarily kill the PS. The reverse biased parallel diode is your friend in those cases.
  • Beanie2kBeanie2k Posts: 83
    edited 2010-02-10 05:26
    Paul Sr. said...
    I have been using one as my bench supply for 2-3 years now and it has been great. Never an issue and the power has been rock solid.

    There are articles all over the net about how people have modified them for their needs. I didn't modify anything - just put a jumper in for the "on" signal in the motherboard connector and made various adapters to plug on to the standard 4 pin peripheral plugs. I have any of the output voltages available in whatever configuration I need them.
    I have been investigating various PC power supplies for an industrial·system at work, and many of the newer units do not have a minimum load requirement·like the old ones did.
  • John R.John R. Posts: 1,376
    edited 2010-02-10 20:51
    Beanie2k said...

    I have been investigating various PC power supplies for an industrial·system at work, and many of the newer units do not have a minimum load requirement·like the old ones did.
    One of the units I'm using at home has a "load resistor" built in, and hence no minimum "external" load.· In general, a "switching" power supply needs some amount of current flowing to work properly.

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    John R.
    Click here to see my Nomad Build Log
  • pmrobertpmrobert Posts: 677
    edited 2010-02-10 22:51
    Thanks for that info John. I guess I'll be looking for newer "junk" in the future!
  • pacmanpacman Posts: 327
    edited 2010-02-11 01:02
    10 ohm, 10W resistor from 5V rail to ground.

    90c

    Even old junk can be useful with just tiny bit of expense...

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