Results 1 to 15 of 15

Thread: running dual power supply

  1. #1
    Member unfguy's Avatar
    Join Date
    Apr 2001
    Posts
    103

    running dual power supply

    I'm interested in running dual power supplies but not in a redundant setup.

    Is anyone aware of a circuit that can be attached to one of the power leads of an existing supply (maybe run inline with a drive power cable) so that it will switch the secondary unit on when power is applied?

    Thanks

  2. #2
    Senior Member Happy Joe's Avatar
    Join Date
    Nov 2003
    Location
    Colorado
    Posts
    825
    You can power a relay off of the 12 V output of the first powersupply and use it to close (short) the startup/turn on pins on the second powersupply (if it is an ATX). I have the pinouts of the powersupply connector here somewhere, if I can find it I'll post it.

  3. #3
    Intimate Member
    Join Date
    Jul 2000
    Location
    Elberton, Georgia
    Posts
    5,330
    http://www.sysopt.com/forum/attachme...&postid=633263

    You will still need to connect an AC plug to the second PSU to power it when it is turned on by the first PSU, but thats no real problem...

  4. #4
    Ultimate Member Ol'Tunzafun's Avatar
    Join Date
    Jun 2002
    Location
    Canadian prairie
    Posts
    3,798

  5. #5
    Guest leprechaun_40's Avatar
    Join Date
    Jun 2002
    Location
    In your dreams
    Posts
    2,671
    You can do it as mentioned above, but why do you want to? Wouldn't it be just as good to get a higher output PSU. Just wondering

  6. #6
    Ultimate Member Billforce's Avatar
    Join Date
    Jan 2001
    Location
    Wee bit O'heaven
    Posts
    1,636
    If not redundant, I am currious WHY not in parallel? Save buying all the relays or switching.
    "Never corner something that's meaner than you are"

  7. #7
    Senior Member Happy Joe's Avatar
    Join Date
    Nov 2003
    Location
    Colorado
    Posts
    825
    I preferr to isolate things like power supplies from one another. That way if one decides to exhale smoke the other is relatively safe.
    Parallel should work just fine.
    Relays are a couple of bucks at my local surplus store, & free at my friendly automotive junk yard.
    Last edited by Happy Joe; 11-20-2003 at 09:27 PM.

  8. #8
    Member
    Join Date
    Jan 2002
    Location
    Brooklyn, NY
    Posts
    80

    Parallel=bad!

    Never connect em in parallel. Each supply will have a slightly different voltage output. But when u connect em in parallel u force em to be at the same voltage. Because of the PSU's low output impedance, this can result in large currents. So dont do it. You'll fry both or cause them to turn off if they have good protection built in.

    Do it the way it was first suggested. Get a 12v relay from radioshack and use one supply to short the green and gray (double check this, though im pretty sure) wires of the other.

  9. #9
    Member unfguy's Avatar
    Join Date
    Apr 2001
    Posts
    103
    This is on a Dell system and the power supply is long and flat, not a standard unit I can pickup at CompUSA or the like

    Thanks for the info all! Now I can get to the experimentin'

  10. #10
    Senior Member Happy Joe's Avatar
    Join Date
    Nov 2003
    Location
    Colorado
    Posts
    825
    OlegB is correct...I was imprecise in my response (sorry). Connecting the two "turn on" wires in parallel shoud be OK. Connecting even powersupplies of the same model and brand in parrallel at their outputs is extremely risky.

  11. #11
    Ultimate Member Billforce's Avatar
    Join Date
    Jan 2001
    Location
    Wee bit O'heaven
    Posts
    1,636
    When I referred to parallel, I was referring to parallel inputs, NOT output. Parallel inputs are virtually the same as series etc. and won't effect the outputs.
    "Never corner something that's meaner than you are"

  12. #12
    Senior Member Happy Joe's Avatar
    Join Date
    Nov 2003
    Location
    Colorado
    Posts
    825
    I understood, I merely wanted to emphasize the point for those people that only scan the thread instead of reading it in detail.
    Enjoy!

  13. #13
    Member
    Join Date
    Jan 2002
    Location
    Brooklyn, NY
    Posts
    80
    Here's the reason I juggest using the relay instead of connecting the "turn on" wire in parallel: I don't know what current is drawn by this input and what current is provided by the motherboard. If it's a standard logic level signal that follows TTL standards or something similar, connecting up to 8 inputs from one output is not a problem. However, I dont have this info.

    The relay is obviously more connections, but its a sure bet. If anyone has questions on the specifics of the relay scheme ask me and I'll be happy to draw some pictures and a schematic.

  14. #14
    Ultimate Member Rugor's Avatar
    Join Date
    Dec 2001
    Location
    Pacific Northwest, Earth
    Posts
    2,694
    Since it is a Dell, I would be very very careful. I don't know if it's the case in your system, but Dell used to have the habit of installing powersupplies that had what looked like a standard ATX power supply and a radically different pinout. Needless to say it burnt a lot of boards and PSUs.
    "Dude you're getting a Dell." Obscure curse from the early 21st Century, ascribed to a minor demon-spirit known as "Stephen?" [sp].

  15. #15
    Member chip55's Avatar
    Join Date
    Jun 2001
    Location
    Ohiya
    Posts
    166
    Rugar is right

    Every Dell,Gateway, even some Compaqs that I have ran into, have different pin-outs than a stock atx power supply

    Be careful

    chip55
    I'm out of my mind..be back in 5 minutes! If I return before I get back, tell me to wait until I get there!

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •