cheap mosfet...why?

Discussion in 'General Electronics Chat' started by hertz.12, Feb 24, 2016.

  1. hertz.12

    Thread Starter Member

    Apr 25, 2015
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    hi all
    i need buy some mosfet like irlz44...but i am not sure what the different between expensive irlz44n (6$..Digikey) and cheap irlz44n(0.35$ in ebay) ????
     
  2. Dodgydave

    AAC Fanatic!

    Jun 22, 2012
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    They're probably from China, maybe poor spec ratings.
     
  3. crutschow

    Expert

    Mar 14, 2008
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    Those ebay ones are likely counterfeit knockoffs and their specs are likely suspect.
    Might be okay for experimentation but I wouldn't trust them in a final circuit.
     
  4. ScottWang

    Moderator

    Aug 23, 2012
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    If you have the link for two components then it will be more easier to identify.
     
  5. Hypatia's Protege

    Distinguished Member

    Mar 1, 2015
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    Please save yourself some 'agro' -- Don't purchase semiconductors from eBay or otherwise from 'private individuals' with whom you have no personal acquaintance - no matter the seller's location, feedback stats, etc... Parsimony is inimical to success in all endeavors! -- Electronics is no exception!:rolleyes:

    With constructive intent
    HP:):):)
     
  6. absf

    Senior Member

    Dec 29, 2010
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  7. atferrari

    AAC Fanatic!

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    So, "malaysian ringgit". Had to google it. :)
     
  8. Hypatia's Protege

    Distinguished Member

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    FWIW - Prices for (ostensibly) compatible versions of the 'same' part number can vary widely -- even from the same supply house -- Counter-intuitively, products approaching end of production are often significantly more costly than their replacements bearing superior specifications -- go figure...

    Best regards
    HP
     
  9. absf

    Senior Member

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  10. Dodgydave

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    Jun 22, 2012
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  11. dl324

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  12. ISB123

    Well-Known Member

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  13. absf

    Senior Member

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  14. ISB123

    Well-Known Member

    May 21, 2014
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    That's true.I only buy from G&C shop when shopping via ebay.
     
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  15. mcgyvr

    AAC Fanatic!

    Oct 15, 2009
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    Laws of supply and demand my friend..
    When you hold the last chocolate chip cookie you can charge whatever you want for it..
     
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  16. hertz.12

    Thread Starter Member

    Apr 25, 2015
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    i will try some cheap mosfet..may be it is just supply and demand rule.

    and what about cheap pic mcu? i don't think microchip manufacturer allow poor spec ratings chips go to the market!
     
    Last edited: Feb 24, 2016
  17. ErnieM

    AAC Fanatic!

    Apr 24, 2011
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    Places like Rochester Electronics make a tidy living selling obsolete and out of production parts.

    Some people just miss end of life announcements and miss out on making lifetime buys for a long term product.

    Some people make things for the military and once something gets qualified the parts inside can never change.

    One place I worked for was buying mil-s carbon resistors in 2010 that had sat on someone's shelf way past their useful lifetime. Even with 10% tolerance so many would fall out in incoming inspection that the vendor stopped allowing returns: no backs!

    Another place I worked at specialized in a few shoulda-woulda been obsolete transistors like the 2n3055. You can buy one for a buck but this place was on the government's QPL (Qualified Parts List) and sold them for over $100 a piece.
     
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  18. WBahn

    Moderator

    Mar 31, 2012
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    Can you provide a link to the $6 Digikey part?

    This is what I am finding:

    http://www.digikey.com/product-detail/en/IRLZ44NPBF/IRLZ44NPBF-ND/811808

    They are $1.57.

    When you buy from Digikey, you pay a significant premium for service -- they have a HUGE selection, they have the overwhelming majority of them in stock, they ship most orders the same day, the parts are brand new, you can pretty much count on them NOT being counterfeit, and they are willing to sell you just one of them. Those factors are worth a LOT to engineer.
     
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  19. hertz.12

    Thread Starter Member

    Apr 25, 2015
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    i think there is no irlz44 with 6$ price! my mistake
     
  20. Techno Tronix

    Member

    Jan 10, 2015
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    Maybe eBay people don't apply a tax on your product or another option is the duplicate product with poor quality. You can inquire about this to the manufacturer directly.
     
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