Restrict DC-DC buck to 5v

Discussion in 'Power Supplies' started by deblen, Jun 8, 2018.

  1. deblen

    deblen Apprentice Elf

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    HI,

    I have Buck converters which output to 5 volt.
    Is their a way I can restrict the out put to 5 volt between the buck and the pixel strip, by way of a fuse or some type of resistor.

    I have heard that when or if the buck fails, the voltage increases, resulting to damage to the pixels

    Thanks in advance

    Deblen
     
  2. AAH

    AAH I love blinky lights :) Community Project Designer Generous Elf

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    The usual way is to use a crowbar circuit set to maybe 5.2V between the buck and the panels. What it does it detects the higher than desired voltage and effectively shorts to ground blowing the fuse. It doesn't look like there's anything on Aliexpress or Ebay off the shelf. The alternate is to use something like a overvoltage relay something like https://www.ebay.com.au/itm/1pc-Vol...505245?hash=item25f5bba49d:g:R50AAOSwpDdVbC8c . There will always be a delay and the relay needs to be sized according to the load. With P10's pulling somewhere in the range of 2-3A per panel the linked 1 is essentially useless for more than 4 panels. You could use the module to control external relay/s but that also adds an additional delay of 10's of milliseconds which may or may not matter.
     
  3. OP
    OP
    deblen

    deblen Apprentice Elf

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    Hi Allan,
    Thanks for the feedback, looks like it is not easy as I thought it would be.

    When you talk about a crow bar circuit, would this be a way to go, if so what would you need to setup.

    Or would you be able to design a cost effective board.

    I am wanting to use the bucks on strips, as I purchased 15 of them last year.

    Deblen
     
  4. OzAz

    OzAz Full Time Elf Generous Elf

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    That's a good ideas @deblen I wonder if @David_AVD has one if @AAH doesn't? I think David runs some of his Halloween stuff from 24/12V power supplies down to 12/5V. A crowbar circuit is relatively simple and shouldn't cost too much to make.
    Wouldn't mind a few of them myself, planning on running 12V to my 5V halloween props.
     
  5. AAH

    AAH I love blinky lights :) Community Project Designer Generous Elf

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    David and I have just been talking crowbar circuits. I have no interest in building them myself. I did think a couple of years ago of implementing them into an Octoscrolla board but decided against it. There is probably options on Feebay or Aliexpress that would do the job or do it with very little modification.
     

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