24VAC Power Supply

Discussion in 'The Projects Forum' started by lesabb, Dec 30, 2014.

  1. lesabb

    Thread Starter New Member

    Dec 30, 2014
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    Hello all,

    A bit of a noobie here (2nd year physics and electronics, bla, bla ,bla) mostly doing audio. I took apart a power module from a Mic pre-amp that uses a 24VAC wall adapter to run. After careful examination (it wasn't that complex actually) I came up with this schemo. Please let me know if it makes sense, did I miss anything? Looks ok to me but...Can I also replace the choke (circled) for a RC filter instead? This would supply +48V and +24 from the 24VAC. The 7824 hooks up to a 33v Zener. Values are not in the Eagle schem yet cause I wanted to make sure it was correct.

    Thanks

    L
     
  2. MrChips

    Moderator

    Oct 2, 2009
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    C1 and C2 are most likely not capacitors.
     
  3. lesabb

    Thread Starter New Member

    Dec 30, 2014
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    Thanks MrChips but I have the PCB right here in front of me. C1 is a Rubycon 1000uF/50V. C2 is 100uF/50V
     
  4. MrChips

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    Well I certainly wouldn't design a power supply like that.
     
  5. lesabb

    Thread Starter New Member

    Dec 30, 2014
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    Any mods to suggest?
     
  6. MikeML

    AAC Fanatic!

    Oct 2, 2009
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    Why not? It is a standard way of making a rectifier/filter.

    109.gif
     
  7. ronv

    AAC Fanatic!

    Nov 12, 2008
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    It's a way to make a voltage doubler. I'm thinking the caps are non- polarized? Maybe not, just 1 cycle.
    I think you can replace the inductor with a wire or a low value resistor.

    edit: polorized
     
  8. MikeML

    AAC Fanatic!

    Oct 2, 2009
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    Yes, polarized. Look at the sim. Also, by playing with the ratio of C1 to C2, you can get anything from almost 2X voltage multiplication to less than 1X...
     
  9. ronv

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    I got a little different picture. Did I miss something?
     
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  10. MikeML

    AAC Fanatic!

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    I'm pulling a lot more current from the output. Also note my C1 and C2.
     
  11. ronv

    AAC Fanatic!

    Nov 12, 2008
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    Ahh yes, I see. I kept C2 low because he said he had a 48 volt supply.
     
  12. MrChips

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    Oct 2, 2009
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    Sorry, I didn't notice the 24V to 48V specs in the TS opening post.
     
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