24VAC->5V@2A converter?

Discussion in 'Electronics & Electrics' started by RussellK, Feb 6, 2013.

  1. RussellK

    RussellK Member

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    So I've got a webcam that wants 5v @ 2A, and I have 24VAC available. Adding a bridge + cap is no problem, although that'd bring up the volts, but I can probably just put in some diodes if the converter is fussy.

    However, finding a converter (and I'd prefer a switcher to linear for various reasons) is proving difficult.

    This thing would do the job:
    http://littlebirdelectronics.com/products/dc-dc-power-module-25w

    But it's not available.

    Any suggestions?
     
  2. 2xCPU

    2xCPU Member

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    Fleabay is littered with DC-DC converters you may find suitable.

    I've been using these. Quite versatile and very cheap (you can't buy the parts to build your own for the same price).
    25W module w/ leads
    100W Module

    2.
     
  3. OP
    OP
    RussellK

    RussellK Member

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    Yeah, I've seen a few on Ebay - but I was hoping for quicker delivery from someone local.

    Edit: that said, it'd certainly do the job, and can't argue with the price.
     
  4. LethalCorpse

    LethalCorpse Member

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    You need one with Vin > 40V. 24VAC rectified and filtered is almost 35V.
     
  5. paulvk

    paulvk Member

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    For a quick and simple way is a 240 to 24 transformer in reverse you get 240v then all you need is a 240 to 5v plug pack
     
  6. OP
    OP
    RussellK

    RussellK Member

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    On the bench, 24VAC RMS through a full bridge and cap came in at 32VDC - I've ordered a batch of 5 boards for $9 off Ebay as suggested by 2xCPU - the LM2596 chip on it will handle 40V, but the input cap is rated at 35V.

    I also found a "Soul" brand cigarette->USB switcher at Domayne for $9 that claims to do 3A from 12-24V, but I can't find a data sheet for its chip - it's marked:
    D&P
    3111
    2B01
     
  7. OP
    OP
    RussellK

    RussellK Member

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    Gotta say that did not occur to me - I'll have to remember that one :)

    Might try it on the bench some time if I can scratch up a 240/24 transformer (and I'm feeling brave).
     
  8. 2xCPU

    2xCPU Member

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    Half wave rectifier? Should be fine if the current low.

    Be thankful you don't want to boost the voltage - those can be expensive!

    2.
     
  9. LethalCorpse

    LethalCorpse Member

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    Blimey, the chip is under $20 and there's barely a handful of passives.
     
    Last edited: Feb 10, 2013
  10. OP
    OP
    RussellK

    RussellK Member

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    I actually bought a similar thing the other day for driving a 24V 4-20mA sensor from a single Lipo:
    http://littlebirdelectronics.com/products/dc-dc-boost-converter
    Although obviously not the standard of that Ebay jobbie (it is haz moar caps). Actually, I do like that they quote the equation for efficiency rather than the actual figure :D
     
  11. Gecko

    Gecko Member

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    I hope someone just forgot a decimal point in there...

    Jaycar have a few kits that might suit http://www.jaycar.com.au/productView.asp?ID=KC5508 could do the job if you can get away with 1.5A. The website doesn't say anything about the input parameters though.

    Otherwise, if you want something quickly (and don't mind paying extra), element14 have a pretty big selection of DC-DC modules.
     

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