i won't buy chinise parts from aliexpress or ebay

[cmrincon]

Hey!

I want to share with you a short story about how not to save money:

Yesterday i was learning about mosfets amps and i decided to use a few 2n7000 N-channel mosfet which i got from aliexpress time ago. I did the maths, even i simulated the circuit. When i mounted the circuit in my breadboard i could see that the mosfet was in ohm region and with a volt above VTh the drain current was more than it could handle, no matter if i slightly drop down vgs, the circuit still didn't work because my mosfet didn't behaves as datasheet and it was useless for amplification ( maybe for switching purposes).

Few weeks ago i get capacitors from another chinise vendor on ali, and i used them to repair a sat receiver. Yesterday i got to repair it again, was hard because i couldn't see at first glance what was wrong with the receiver, but after a few test i repaired it. Guess what was wrong? the chinise capacitors!


I can't belive that all chinise parts are like this ones, and i gave my last chance to lcsc. I bought some MMBTH10, ceramic caps and few rf npn bjts from not chinise manufacturer.
In a month i will know if i will loose the money or it is a cheap way to buy parts.
Don't buy not original parts!!

[Quarlo Klobrigney]

Internet grammar police here. ..You have employed a double negative. Your statement reads that you will buy from Aliexpress.

[Pinkus]

Well, I guess you learned from that lesson.... as many of us did before.
Unfortunately there are enough cheapos left so the problem will not vanish.

[Mechatrommer]

i won't never buy chinise parts from aliexpress or ebay = i will buy chinise parts from aliexpress or ebay
Don't buy not original parts!! = buy original parts!!
both points are valid imho... its just we learn to read the spec and make it half or a third capability when it comes to china clone parts.. with 1/10X the price, still bang for the buck, in certain occasions. ymmv.

[cmrincon]

I'm sorry, i modified the topic in order to avoid confusions!

[exe]

Welcome to the club .

I do buy ICs from ali sometimes, but only if don't have another source, or if I'm willing to accept the risk and I can verify part's performance before putting it into the circuit.

What was motivation to buy such a jelly bean component from China? It costs nothing from any reputable distributor. The only catch is "minimal order" and delivery cost .

[SilverSolder]

I happily buy Chinese parts on eBay.  Most of the time, they are good.  When they are not, I raise a case with eBay and get a refund.  There isn't really any risk involved, but you do have to test/verify the parts when you get them.

[wraper]

I happily buy Chinese parts on eBay.  Most of the time, they are good.  When they are not, I raise a case with eBay and get a refund.  There isn't really any risk involved, but you do have to test/verify the parts when you get them.

"Good" in quote marks. When they work in your circuit does not mean they are genuine or meet specifications. Often you can get recycled crap sold as new and with 20% of duds. Even when parts are genuine there is high chance they were re-marked with newer date code and have poor solderability due to old age and poor storage conditions.

[Quarlo Klobrigney]

Probably been seen here before, but it was new to me..

[tunk]

Not everyone have had the same bad experience:
Andreas Spiess recently tested some transistors from
AliExpress and found that all except one were within spec:

[NivagSwerdna]

FWIW I've bought lots of chips from China that do work... and some that don't.   For NOS items you probably don't have much choice as to supplier.
For any quantity or long term supply purchasing then you need to go to a proper supplier not swim with the sharks on ebay.

[SilverSolder]

I have had bad/fake transistors from eBay, but most of the time they are good.  If the price is low enough, I don't mind testing - for hobby purposes.  Anything serious, and I would head for a serious supplier.

[DBecker]

I was bitten badly back in the great power MOSFET shortage a decade ago with re-marked lower capability parts.  I've also gotten obviously fake security transponders.
Parts that are obsolete or in high demand are commonly counterfeit/re-marked.  Cheap commodity components, or parts that went out of production in favor of a similar new part can be a great deal for a hobby project where you don't need a large or long-term supply.

[janoc]

Not everyone have had the same bad experience:
Andreas Spiess recently tested some transistors from
AliExpress and found that all except one were within spec:

That's not quite true. They were good enough for his project, but a claim of a part "being within specs"  (as in datasheet specs) is something very different. He didn't really test that - and I am prety sure some would have failed if he has pushed them to the actual published datasheet specs. The testing in that video is a good sanity check that you didn't get something wildly different or completely fake (like those Sparkfun "ATMegas") but it won't tell you if the part is really genuine and meets all its specs.

That may or may not be important for you, it depends on your project.

However, it is an important distinction to make or you will get a surprise that that MOSFET or a voltage regulator blew up at half of the rated current or that the opamp is 3x noisier and has 1/4 of the expected slew rate - all due to cheap lower spec parts being remarked and sold as higher spec ones and your circuit actually taking advantage of the published specifications.

Recycled but original parts are not necessarily a problem if you know what you are buying (given that you are unlikely to find another source anyway) - but if someone is selling a part that is 20-30 years out of production and claims it is new, with recent date codes, then there is something fishy there ...

[Marco]

Yesterday i was learning about mosfets amps and i decided to use a few 2n7000 N-channel mosfet which i got from aliexpress time ago.

True 2n7000s are the most statically sensitive component a hobbyist will handle (but shouldn't). You can juggle PC memory made with the tiniest of modern processes without much fear, but look wrong at a 2n7000 and it's kaput.

Breadboarding with them is silly, use parts with proper gate protection.

PS. a lot of them have gate protection now regardless of the datasheet, but you might have some NOS of proper ones.

[cmrincon]

What was motivation to buy such a jelly bean component from China?

Sometimes i'm bored and i buy things that i really don't need, but i think that they will be useful in the future, they cost only a few euros and i think that it is like a little adiction.

When i buy a part from ebay/ali i will never expect to have parts with the exact behaivor than the original one, but at least i expect that they would have similar specs as i'm not a proffesinal and this is only my hobby. Maybe this are only a few bad experiences in a short period of time.

Breadboarding with them is silly, use parts with proper gate protection.

Do you have any mosfet suggestion? i'm searching for a mosfet with a low input/output capacitance (100p-200p max) and a max power dissipation of 1 w

[exe]

Do you have any mosfet suggestion? i'm searching for a mosfet with a low input/output capacitance (100p-200p max) and a max power dissipation of 1 w

Well, I do Tune search to your liking https://www.digikey.nl/products/en/discrete-semiconductor-products/transistors-fets-mosfets-single/278?k=&pkeyword=&sv=0&pv1174=121220&pv1174=121231&pv1174=121242&pv1174=121250&sf=1&FV=-8%7C278%2Cmu200pF%7C2263%7C1&quantity=&ColumnSort=0&page=1&nstock=1&pageSize=25

[Psi]

The problem people run into with aliexpess is ordering by price and buying the cheapest option, because they are so used to doing that on other sites.

The correct thing to do is order by price and then look for the different price groupings. They will be in clusters.
The lowest price grouping should be ignored at all costs. This is where you will find total fakes and factory rejects that are way out of spec.

The 2nd and 3rd price grouping is what you want to order. These will be good parts.

NOTE1: Even 2nd and 3rd group may still be factory rejects but will be good enough 99% of the time.  If you want 100% good and in spec parts your buying from the wrong place. Aliexpress is not for that.
Aliexpress is for when you don't mind a little risk in order to save 50-90% of the cost from a genuine supplier.  Expecting 100% genuine pars at 50-10% price is stupid.

NOTE2: Never buy from an Aliexpress seller with less than 95% feedback score.

NOTE3: Pick your battles, if you're building something first decide what parts are critical to you and what parts don't matter much.
You might choose to get your transistors and IC's from digikey but get your LEDs, resistors and switches from aliexpress because those are less critical. If the LED brightness is a little off it wont matter.

[wraper]

The 2nd and 3rd price grouping is what you want to order. These will be good parts.

99% good is gross overestimation. Depending on what you buy they easily may be the same crap as the cheapest tier.

[floobydust]

If you buy the lowest price parts from a store that also sells pantyhose and cosmetics, well- it might be high risk.
Some eBay/Ali stores are a bit more expensive and sell OK parts but never in anti-stat packaging or with real markings. There seems to be a mystery laser doing all IC/transistor markings in china.

Lately I just buy from Digikey or Mouser. Because it is false savings after the wasted time pissing around with fake/dud/counterfeit parts.

[Marco]

Do you have any mosfet suggestion?

Use automotive rated parts, even if it's not on the datasheet they can't pass the tests without gate protection. I only found one through hole one, the BS107P.

I'm not sure how many versions of 2n700x without gate protection are even made any more, but Infineon says their one is ESD class 0 so it seems they are still being made.

[exe]

An alternative could be an smd part with a through-hole adapter board if TH mounting absolutely needed. Or, may be, BJT would be a better option? We need to know more about the application...

[SilverSolder]

[...] Sometimes i'm bored and i buy things that i really don't need [...]

Welcome to the club...

[janoc]

Yesterday i was learning about mosfets amps and i decided to use a few 2n7000 N-channel mosfet which i got from aliexpress time ago.

True 2n7000s are the most statically sensitive component a hobbyist will handle (but shouldn't). You can juggle PC memory made with the tiniest of modern processes without much fear, but look wrong at a 2n7000 and it's kaput.

Breadboarding with them is silly, use parts with proper gate protection.

PS. a lot of them have gate protection now regardless of the datasheet, but you might have some NOS of proper ones.

Eh, they are OK, even on a breadboard if you are careful.

IMO, it is a good opportunity to learn and use proper ESD precautions, e.g. an antistatic mat on the workbench and make sure the gate is never left unprotected (e.g. with a resistor/zener/TVS diode) somewhere where a user can "zap" it (e.g. via a connector). There are plenty of much more common components that are as easy if not easier to kill and are in common use by hobbyists, such as many of the "neopixel" smart LEDs, laser diodes, some CMOS chips ... Should we avoid all of these too?

It is much better to learn this by frying a LED or an 2N7000 than a more expensive part, in my opinion.

[Marco]

If there's Neopixel's with ICs without input protection you should definitely avoid them, there's no real excuse for that. Half century old CMOS ICs without input protection are curiosities you shouldn't be wasting on a practical circuit either. Junctions even of a laser diode aren't as vulnerable as a MOS gate, they can at least avalanche a little without damage.