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do I need a circuit?

Discussion in 'General Electronics Discussion' started by donkey, Feb 11, 2013.

  1. donkey

    donkey

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    Feb 26, 2011
    http://www.ebay.com.au/itm/120935947271?ssPageName=STRK:MEWNX:IT&_trksid=p3984.m1439.l2649
    i got 3 of these little suckers and I washoping there would be a nice big label saying voltage in / voltage out.... well there is but the Vout has 3 poles..... then I also saw this component used with a couple capacitors on a circuit board, Now I am trying to figure out if I can simply hook it up to 12v and it outputs 2 5volt rails with a common ground?
     
  2. Harald Kapp

    Harald Kapp Moderator Moderator

    9,053
    1,818
    Nov 17, 2011
    Check this. It seems that you have to ask specifically for a datasheet to have it sent to you.
     
    Last edited: Feb 11, 2013
  3. donkey

    donkey

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    Feb 26, 2011
    Home > Clothing & Accessories > Women > Vest > 10x KIM-055L Step Down DC-DC Voltage Regulator Module
    ok thats a fun place to hide the dc-dc step down converters... in with the womens vests, no wonder I can't out anything lol
     
  4. donkey

    donkey

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    Feb 26, 2011
  5. donkey

    donkey

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    Feb 26, 2011
    http://www.aliexpress.com/store/pro...8A-packet-transfer-3-3V/314688_524734396.html
    this page helped a little, I have rough idea on the cap value. but what does "Note: between the input and output to ground to above ground plus a minimum 220uf or 22uf capacitor common point solution of the above solid-state capacitor filter, otherwise the output voltage is not normal and there is noise! Need for special solid-state output filter capacitor:" mean exactly?
    the pins on the base of the module read Vin and gnd on one side the other says Vout(this has 2 pins) and Gnd.
    I am assuming the gnd beside the Vin is the ground for Vin and vice cersa but the extra pin and no details on the product is getting me confused
     
  6. Harald Kapp

    Harald Kapp Moderator Moderator

    9,053
    1,818
    Nov 17, 2011
    My guess: that is an automatic translation.

    Start with two 220µF capacitors, one from input to GND, one from output to GND. Add 2 100nF ceramic capacitors, in parallel to the electrolytics.

    Vout has 2 pins possibly to bettter conduct the high load (a single pin might be overloaded at 5A).
     
  7. donkey

    donkey

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    [​IMG]
    something like that? and then put 2 100nf caps ontop of the 220µf ones?
    that was just a quick sketch sorry if Its bad but I work better with pics
     
  8. Harald Kapp

    Harald Kapp Moderator Moderator

    9,053
    1,818
    Nov 17, 2011
    Something like that, right.
    Observe the polarity of the electrolytic caps.
     
  9. donkey

    donkey

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    Feb 26, 2011
    yep will do thank you heaps harald. I always getjumbled up with caps and was trying to figure out the differences between the ceramic and electrolytic, thank you wiki lol
     
  10. gorgon

    gorgon

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    Jun 6, 2011
    Looks like the output capacitor is 220uF and the input capacitor is 470uF on most modules. You should never exceed 1000uF, due to stability. This is general, said on the kgcomp site.
     
  11. Harald Kapp

    Harald Kapp Moderator Moderator

    9,053
    1,818
    Nov 17, 2011
    Another note: unless this module is insulated from input to output, you should connect both GND pins with a wide trace on a PCB or using thick wire.
    AS I menioned, there Vout pins for carrying the high current. So why should a single GND pin suffice? It won't,
     
  12. donkey

    donkey

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    Feb 26, 2011
    so are the grounds to be connected too?
     
  13. Harald Kapp

    Harald Kapp Moderator Moderator

    9,053
    1,818
    Nov 17, 2011
    That's what I wrote:
     
  14. donkey

    donkey

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    Feb 26, 2011
    ok thats new. I am turning the net upside down trying to find a schematic using thedevice or a datasheet, nothing as yet. stupid me thought I simply put this on my 12volt battery and got 5volt out.
     
  15. Harald Kapp

    Harald Kapp Moderator Moderator

    9,053
    1,818
    Nov 17, 2011
    Add the caps and it should do your bidding.
     
  16. donkey

    donkey

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    Feb 26, 2011
    will buy the parts thursday and see how I go. harald you are a champion myfriend thank you so much for your help
     
  17. donkey

    donkey

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    Feb 26, 2011
    hey harald got a question what voltage rating do I need? I can get my hands on some 10v 16v 25v 50v or 63 v I was thinking the 16v range but thought I would triple check
     
  18. Harald Kapp

    Harald Kapp Moderator Moderator

    9,053
    1,818
    Nov 17, 2011
    It is generally a good idea to have electrolytic capacitors rated at least 50% above the nominal operating voltage of the circuit.
    Typically I would chose a 16V type for the 5V output and 25V capacitors for the 12 V input.
    But 10V caps for 5V and 16V caps for 12V may be used, too. You risk a bit shorter lifetime, depending on possible overvoltage and how near that comes to the rated voltage of the capacitor.

    If you don't want to diversify too much, you can use 16V or 25 V capacitors on both input and output. It's a matter of available space (cost should differ only slightly).

    Harald
     
    Last edited: Feb 13, 2013
  19. donkey

    donkey

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    Feb 26, 2011
    imight go the 25V ones then. ty harald yet again. this is going to help out so much
     
  20. donkey

    donkey

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    Feb 26, 2011
    harald its working tysm my friend
     
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