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Cheap switching supply instead of transformer

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  • Cheap switching supply instead of transformer

    Topping makes a very quiet 5V DAC supply for $115. Though building a very good linear supply is not hard, but by the time you get all the parts and a nice case, you are pushing the price for DIY. It occurred to me, one could reduce the price by scrapping the expensive transformer with a 12V switcher from the junk box. Old printer or laptop supply. Then follow it with an $8 LDO adjustable kit off Amazon. Should knock about $35 plus shipping off the project cost. The kit I am talking about would cost about $35 if buying parts from Mouser or Digi-key and has a circuit board. So the only expensive part is a case.

  • #2
    What level of PS noise reduction is built into the DAC?

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    • #3
      We have no idea. I am sure it varies from product to product. What we don't know is what is done internally. Do they run a DC-DC converter and inverter for +/- 15V for the linear stage? That could cause more noise than the input. I seriously doubt the whole thing runs off 5V.
      My idea was more to avoid another $35 for a transformer when I have a 12V 1.2A switcher from a printer I can feed the linear reg with.
      I do know the Toppig supply uses a cascaded linear regulator.

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      • #4
        There's <$2, Adjustable LM317 based linear regulators on eBay that can front end the laptop power supply such as this one. Ignore the "buck" marketing description. It's a linear regulator.

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        • #5
          Already have better regulators with LDO chips on order. ( $8) I am talking about using a switching supply instead of a transformer and rectifier with a large filter bank.

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          • tvrgeek
            tvrgeek commented
            Editing a comment
            BTW, boards I ordered have LT1083's in them. Much improved over 317's.

        • #6
          I purchased an industrial 12-15 volt surplus power supply new in box for $55. It will supply 33 amps of regulated B+ for whatever your needs are.
          Might check EBAY to see whats out there.

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          • tvrgeek
            tvrgeek commented
            Editing a comment
            That's fine but has nothing to do with a cheaper way to build a 5V 1A very clean power supply.

            FWIW, I have an e-bay 0 to 30V 40A bench supply. Very handy testing the various circuits in my Triumph I am restring. Proved a friend had a bad Lucas fuel pump as it was supposed to pump with 8V, but required 11. Useless for audio work. I have a modified Heath tracking supply I use for that.
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