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Thread: Question: -5V DIY circuit for supergun

  1. #1
    Crossed Swords Squire
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    Question: -5V DIY circuit for supergun

    Hi,

    I've bought off ebay a cheap psu with +5 +12 -5V supposedly available at the terminal.
    -5V rail is actually blanked off and there is no extra tapping point on the coil/winding.

    Could someone indicate how to build a circuit that can draw -5V out of available positive voltage?
    Not sure how much current does KI or MK pcb require but it should 1/2 amp to 1amp at most I guess.

    Thanks

  2. #2
    Watches My Little Pony
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    At a glance, you might try something like this:
    https://www.digikey.com/product-deta...190-ND/2047961

    Ignore the fact that it's an "evaluation" board. That just means they're selling it cheap.
    I turned off signatures. So should you.

  3. #3
    Crossed Swords Squire
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    That's exactly what I am looking for but the $50 for int' shipping is a no go.

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    . Yodd's Avatar
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    I would look into the Negatron. They have been pretty popular option in cabs or superguns that didn't have the -5v rail.

    https://www.dimensionengineering.com/products/negatron

    They appear to have pretty inexpensive international shipping.



    edit: damn, James beat me to it.
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  6. #6
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    Quote Originally Posted by Xian Xi View Post
    Use a Negatron.

    https://www.dimensionengineering.com/products/negatron

    If you need me to ship you one let me know. I'm about to order some so it would be about $26 shipped to you.
    Quote Originally Posted by Yodd View Post
    I would look into the Negatron. They have been pretty popular option in cabs or superguns that didn't have the -5v rail.

    https://www.dimensionengineering.com/products/negatron

    They appear to have pretty inexpensive international shipping.



    edit: damn, James beat me to it.
    Thanks for the tip, 500mA should be enough for KI or MK.

    @James, Ok I'll send you the payment via PayPal shortly. Thanks

  7. #7
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    Get a 9V battery, swap the leads and put a voltage divider to get it down to -5V!

    On a more serious note, if you're looking for a 100% DIY cheap solution, this might fill the bill:

    http://www.aaroncake.net/circuits/vinvertr.asp

    it's an extremely simple circuit, you can do better with other components (opamps and such), but it's gonna need more components (ie: added costs).

    EDIT: ok, just saw you went for another solution. Oh well, I'll leave this here for other ppl :P

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    Quote Originally Posted by donluca View Post
    Get a 9V battery, swap the leads and put a voltage divider to get it down to -5V!

    On a more serious note, if you're looking for a 100% DIY cheap solution, this might fill the bill:

    http://www.aaroncake.net/circuits/vinvertr.asp

    it's an extremely simple circuit, you can do better with other components (opamps and such), but it's gonna need more components (ie: added costs).

    EDIT: ok, just saw you went for another solution. Oh well, I'll leave this here for other ppl :P
    That's really cool! thanks for sharing

  9. #9
    JammaNationX
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    Quote Originally Posted by donluca View Post
    Get a 9V battery, swap the leads and put a voltage divider to get it down to -5V!

    On a more serious note, if you're looking for a 100% DIY cheap solution, this might fill the bill:

    http://www.aaroncake.net/circuits/vinvertr.asp

    it's an extremely simple circuit, you can do better with other components (opamps and such), but it's gonna need more components (ie: added costs).

    EDIT: ok, just saw you went for another solution. Oh well, I'll leave this here for other ppl :P
    Nice but 280mA isn't much. Plus he would need a regulated 6v supply to get a regulated -5v output.

  10. #10
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    Quote Originally Posted by Xian Xi View Post
    Nice but 280mA isn't much. Plus he would need a regulated 6v supply to get a regulated -5v output.
    He can just use the +12V and use a voltage divider (two resistors) to get it down to 6V.

    I'm not sure how much current boards draw from the -5V but my guess is something very very low, not exceeding 100mA.

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