Small Power Supplies

Discussion in 'DIY' started by ultrabike, Aug 2, 2018.

  1. ultrabike

    ultrabike Measurbator - Admin

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    Alright. I bought this thingy for my 2i2:

    https://www.ebay.com/itm/Balanced-XLR-Unbalanced-RCA-to-unbalanced-balanced-preamp-preamplifier-board/271947481068?ssPageName=STRK:MEBIDX:IT

    It maybe garbage but it's probably less garbage than the 2i2 single ended interfaces. Would love to squeeze as much juice from the balanced I/O.

    So awesome.

    Now I need a small power supply with V+ V- and COM. Preferentially 12 to 15 Volts and at least maybe about 500mA for cheap.

    I found this (RD-3513 variant):

    https://www.meanwell.com/webapp/product/search.aspx?prod=RD-35

    Someone said they had bad luck with some random MW PS.

    So the question is, for small projects, what are good and reasonably priced options for small integrated power supplies? Any recommends are welcome.

    I kind of looked into MW because I've seen their IRS series integrated in quite a few projects with good success. Anyhow. Thanks for any suggestions.
     
    Last edited: Aug 2, 2018
  2. Cspirou

    Cspirou They call me Sparky

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  3. maverickronin

    maverickronin Friend

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    Does it have to be completely prebuilt? I like to scavenge transformers from old wall-warts at secondhand stores. If you're up for a little more DIY a few diodes, caps, and maybe some regulators you can make yourself a small LPS.
     
  4. Cspirou

    Cspirou They call me Sparky

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  5. ultrabike

    ultrabike Measurbator - Admin

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    I could do that, but then I might have to screw around with a circuit board kit which is fun, but will add to the cost.

    One of the reasons I got pretty exited about that MW is that it is about $15 + $3 to $10 shipping. All I need is to slap into it a power cord + switch and done.

    A concern would be if the PS is a POS that needs a lot of baby sitting with further regulators which then makes the solution a no go for the simple application I have in mind. Then one just might as well build one from scratch.

    That looks nice.

    But it seems it needs some kind of a step down transformer or wall wart to get input voltage down to something less than 40 V or so.

    EDIT: Based on what they claim in the page, if I need 15V I might want to consider bringing the input down to something like 20 VAC. Not ruling it off. It's a good option.
     
    Last edited: Aug 2, 2018
  6. maverickronin

    maverickronin Friend

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    I didn't even look up the price, but wow, that is surprisingly cheap...
     
  7. dBel84

    dBel84 Friend

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    i have also seen meanwell used by a number of vendors as reliable smps supplies, I have assumed general reliability and low noise compared to others.

    the silent switcher is similar to the unit I used for my SE-Balanced adapter, but i suspect Jan paid more attention to noise floor - 5V @ 2A ( easy to find 5V wallwart ) , it is a DC-DC converter which takes a single 5V feed and puts out dual 15V rails.

    Not sure I like the signal processing in this unit - uses a single inverting opamp to create the opposite signal. I know that the DRV334 is not ideal but I at least think it is a better way to implement chip for generating a balanced signal.

    ..dB
     
  8. ultrabike

    ultrabike Measurbator - Admin

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    https://www.amazon.com/gp/product/B07CKN9FG1

    Can get it even cheaper from digikey since it's like 12 oz and may have the cheap USPS option for like $3.

    It's also super small.
     
  9. ultrabike

    ultrabike Measurbator - Admin

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    You mean the balanced/unbalanced cheap deal I bought from ebay. Yeah. It's not optimal. One could reduce the noise floor by putting some buffers at the front and all that stuff.

    But doing so might be overkill for the 2i2. I only need like -91 dB of THD+N.

    The interface is only going to be used as line I/O interface. So no stringent loading requirements. No gain needed at all either.

    EDIT: BTW The DRV134 is indeed very interesting. However, the cheap deal from ebay includes even the connectors installed. Cannot argue about performance, yet. But if it cuts the mustard for $26, that's awesome sauce. If not, no biggie. No big loss.
     
    Last edited: Aug 2, 2018
  10. maverickronin

    maverickronin Friend

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    If I was out of regulators I might as well just order the whole psu from Mouser or Digikey instead.

    Plus now that I think about you'd need low dropout regulators to even get close to the voltage you want from the usual 12V wall-warts at thrift stores.

    If you're adventurous enough there's something else super cheap you could try. All the thrift stores around me are full of these HP printer SMPS that are 3 terminal 0V/+16V/+32V that you could probably use as a bipolar supply. I have one in my box of spare wall-warts that still has its 99¢ price tag on it. Never got around to testing it though...
     
  11. dBel84

    dBel84 Friend

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    if it doesn't hit me up as I have a few Spare DRV134's and I like to load them with a front end buffer for stability - I used BUF634 which is waaay overkill but as you said, gets the job done.

    The ebay unit does look very neat and compact and you could hardly buy the connectors alone at that price.

    ..dB
     
  12. Cspirou

    Cspirou They call me Sparky

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  13. ultrabike

    ultrabike Measurbator - Admin

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  14. Azimuth

    Azimuth FKA rtaylor76, Friend

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    There was a medical MW that was the one that used for the Gilmore Lite MK2 that sounded pretty dang great. I never thought SMPS's could sound so good.

    Matt had another generic SMPS in the box, but it sounded very terrible.

    I am thinking about getting this medical devices one for my USB recording interface:

    https://www.arrow.com/en/products/gsm25b05-p1j/mean-well-enterprises
     
  15. ultrabike

    ultrabike Measurbator - Admin

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    Just got the part. It is a little bigger than expected, but indeed small. We'll see if it does the job.
     
  16. Azimuth

    Azimuth FKA rtaylor76, Friend

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    [​IMG]

    Sorry...couldn't resist. :p
     
  17. Ardacer

    Ardacer Almost "Made"

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    That was me. Sorry I forgot to tell you which ones. RS-100-12. I have 2 units. Terrible coil whines. Relatively good regulation and noise. Totally unuseable due to coils singing like mad.

    Also I'm sorta active sometimes at eevblog forums. People hate on meanwell there a lot, and they're mostly all pro electrical engineers (don't know what to think of it). My units suck balls.
     
  18. mitochondrium

    mitochondrium Friend

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    If they suck balls it is handy to have two of them
     
  19. Ardacer

    Ardacer Almost "Made"

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    They give off a tingling sensation. Saves the cost of premium lubes.
     

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