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Thread: Confused about power supply. 24v PS using buck converters down to 5v.

  1. #1
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    Default Confused about power supply. 24v PS using buck converters down to 5v.

    So lets say I'm going to have 450 5v pixel nodes ran off a power supply. 3 amps per string totaling 27amps at 5v. How do I figure out what amperage/wattage 24v power supply I would use? I tried using ohm's law but I just can't seem to get it.

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    Default Re: Confused about power supply. 24v PS using buck converters down to 5v.

    Save yourself $$$ both on hardware and hydro

    Use 5v 60 power supply

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    Default Re: Confused about power supply. 24v PS using buck converters down to 5v.

    Quote Originally Posted by angus40 View Post
    Save yourself $$$ both on hardware and hydro

    Use 5v 60 power supply
    I was originally going to do that but getting 5v's to the far strips would need some serious wire gauge. Or am I doing something wrong?

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    Default Re: Confused about power supply. 24v PS using buck converters down to 5v.

    Assuming perfect conversion,
    5v @ 27A = 135 w
    24v @ 135w = 5.625A
    Throwing a bunch of bucks into the mix and you will likely use a bit more.
    Here is where I found the calculator.
    https://videos.cctvcamerapros.com/vo...tts-conversion

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    Default Re: Confused about power supply. 24v PS using buck converters down to 5v.

    Power / voltage = current.
    Buck converters are about 80% efficient.
    Yes you can use smaller guage wire with less loss using a higher voltage. My show has over 60 buck converters in it.


    2018 - Moving and going to visit my Daughter in New Zealand. Most likely I will be dark or nearly dark, Some static stuff that is simple to put up.

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    Default Re: Confused about power supply. 24v PS using buck converters down to 5v.

    Quote Originally Posted by MikeKrebs View Post
    Assuming perfect conversion,
    5v @ 27A = 135 w
    24v @ 135w = 5.625A
    Throwing a bunch of bucks into the mix and you will likely use a bit more.
    Here is where I found the calculator.
    https://videos.cctvcamerapros.com/vo...tts-conversion
    Makes complete sense how you figured that out, thanks!

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    Default Re: Confused about power supply. 24v PS using buck converters down to 5v.

    a few years back I wrote this informal paper that might help you.

    I hope it attached
    Attached Files Attached Files

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    Default Re: Confused about power supply. 24v PS using buck converters down to 5v.

    Quote Originally Posted by MartinMueller2003 View Post
    My show has over 60 buck converters in it.
    Can you give any links/info on the buck converters you're using? I've tried 3 different types and none of them work so far. I order them in quantities of 5 so I have 15 defective buck converters. They don't drop the voltage at all.

  10. #9
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    Default Re: Confused about power supply. 24v PS using buck converters down to 5v.

    If you have 3 different lots of defective Bucks, you likely have an installation issue.

    I like using smaller area transformers...usually weatherproof. 120V go a long, plus the transformer usually fixes voltage drop. I have no oversized wire in my layout.....but I have a lot of 120V, and much more efficient.
    Last edited by mrGrumpy; 06-11-2018 at 11:07 AM.
    In Lights Therapy

  11. #10
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    Default Re: Confused about power supply. 24v PS using buck converters down to 5v.

    Quote Originally Posted by mrGrumpy View Post
    you likely have an installation issue.
    I wish that was the case. These don't work on the bench, right out of shipping. The ones I have are based on an LM2596 and usually fail in a fully closed state. The trim pot was the culprit in one batch but the other 2 batches seem to have bad regulators. Given the price and quality I suspect they have some counterfeit parts. I have a dozen TI LM2596's on order but still don't trust the circuit .

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