cheap mosfet...why?

Thread Starter

hertz.12

Joined Apr 25, 2015
41
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) ????
 

crutschow

Joined Mar 14, 2008
25,121
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.
 

Hypatia's Protege

Joined Mar 1, 2015
3,223
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) ????
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:):):)
 

Hypatia's Protege

Joined Mar 1, 2015
3,223
Are you sure a IRFZ44N costs $6.00?

I checked with Element 14 (AKA Farnell), and they only cost slightly over $2.00 ($1 ~= RM4.20).
Dont tell me Farnell is selling counterfeit parts...

http://my.element14.com/Search?catalogId=15001&langId=83&storeId=10188&categoryName=All Categories&selectedCategoryId=&gs=true&st=irfz44n

Allen
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
 

Thread Starter

hertz.12

Joined Apr 25, 2015
41
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:

ErnieM

Joined Apr 24, 2011
8,046
Counter-intuitively, products approaching end of production are often significantly more costly than their replacements bearing superior specifications -- go figure...
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.
 

WBahn

Joined Mar 31, 2012
25,918
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) ????
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.
 
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.
 
Top