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Thread: "Y" Power connectors

  1. #1
    Constant Bitrate GRUNT's Avatar
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    "Y" Power connectors

    I think this has been asked before, can't find the thread.

    Would it safe to use "Y" power connectors, for power to the motherboard and drives? One end would be connect a DC-DC power supply inside the case, and the others accessible for the outside of the case. This would be used for connecting ACDC power supply for in house use.

    Only one power supply would be ON at anyone time.
    But I'm worried that, when connecting the ACDC supply when the DCDC supply is connected. Would it damage the DCDC supply?
    If so what would I need to make it safe?

    This is a link to a video clip of my carPC case mmsauto.mpg 4.7Mb, before I installed the EPIA 800 with my Sproggy, (from Mastero).

    Now that I have the Sproggy inside the case I would like to build the "Y" power connectors.

    This is something I have wanted to do for months, just not had the time.

    Thanks for your help.

  2. #2
    Unregistered User ODYSSEY's Avatar
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    I once connected two AT PSU's 12 volt lines together, for more Amps. Turned the first one on and it started to spin the second PSU's fan. I never did turn the second PSU on. I was too scaried I must blow something up. I ending up using a better PSU (more Amps).

    That being said, nothing should blow up. As long as one or the other PSU is off. I don't know about possible long term damage.
    ODYSSEY

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  3. #3
    FLAC
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    understand now, I am the furthest thing from a EE there is.. I think it would be ok if you used diodes on the hot lines.
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  4. #4
    Unregistered User ODYSSEY's Avatar
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    That would be a decent about of diodes. You would have to split most of the lines on the "Y" going to the DC-DC PSU. This would block the power from being feed into the DC-DC PSU. Don't forget diodes will drop the voltage abit. This method would be the best way to assure that no power is getting feed into the DC-DC PSU.

    I'm not an EE either.

    Have you tried to power you DC-DC with the 12 volts from your AC/DC PSU? ATX PSUs require you to short two pins to turn the supply on. The green (Pin 14) is designated as the power on line, while the black (Pin 13) is just a ground line.
    ODYSSEY

    Quote Originally Posted by Tidder View Post
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    All information expressed in this post is my opinion, and should not be regarded as a statement of fact.
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  5. #5
    Constant Bitrate GRUNT's Avatar
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    Have you tried to power you DC-DC with the 12 volts from your AC/DC PSU?

    I did think of that, but thought is would not be a good idea.

    The other option would be to build/find a switch to break the lines to the DCDC when ACDC was connected?

    I have a printer and a serial switch box, that would do the job,
    but I'm not sure if the switch would handle the load.

  6. #6
    FLAC
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    Re: "Y" Power connectors

    Originally posted by GRUNT

    Now that I have the Sproggy inside the case I would like to build the "Y" power connectors.

    This is something I have wanted to do for months, just not had the time.

    Thanks for your help.

    I don't understand why people don't just use a AC to DC 12 volt converter. This Y issue has come up so many times. Just take the 12 volts from your AC-DC power supply that you want to spend so much time building a Y connector for and just connect the 12 volts from one of the hard drive connectors to the 12 volt input of your DC-DC power supply. Why is this so hard? It seems a lot easier than spending 30 dollars on diodes. What could have possibly made you think this isn't a good idea? It is Ten times better than a Y connector. Will all the parts on the motherboard that are 3.3 volt run at 2.8V? Sounds like a BAD idea to me.


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  7. #7
    Constant Bitrate GRUNT's Avatar
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    just connect the 12 volts from one of the hard drive connectors to the 12 volt input of your DC-DC power supply.

    Did not know that it would be safe to do that.
    I know you have much more experience about this subject than I do.
    So if you think it's OK.
    For me this would be the best and easiest option.

    Thanks for clearing this.

  8. #8
    FLAC
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    Originally posted by GRUNT
    just connect the 12 volts from one of the hard drive connectors to the 12 volt input of your DC-DC power supply.

    Did not know that it would be safe to do that.
    I know you have much more experience about this subject than I do.
    So if you think it's OK.
    For me this would be the best and easiest option.

    Thanks for clearing this.
    You might need to put a load on the +5 volts. If you have some old hard drives, you might have to plug them in just so the min load requirement is met on the 5 volts..

    Other than that, it is cheep 12 volts at 8 amps?
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  9. #9
    FLAC MP3DUB's Avatar
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    When I was planning the current rev of my car pc that had me looking into this a few months ago, I wanted both in the same case, which would have allowed me to use either power supply in either setting without any external boxes. As in this thread, some said it would be ok to just hook both up, some said diodes, some said switches. Im still just running a AC-DC psu off an inverter, so I never looked into the matter further, but if someone had some money and old hardware to spare, the most conclusive answer could be generated by just hooking them both (dc-dc and ac-dc) up and seeing what happens.
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