i won't buy chinise parts from aliexpress or ebay

[Psi]

Buying crystals from aliexpress sounds like a terrible idea.
As i said before, choose your battles.

[wraper]

Buying crystals from aliexpress sounds like a terrible idea.
As i said before, choose your battles.

And why do you think buzzers will be any different? Also SMT piezo buzzer is not nearly $2 at digikey unless you want to go for expensive option. And here you go, almost as cheap as your $3 for 10 and has datasheet (BTW there are actually none on aliexpress that match your description) https://lcsc.com/product-detail/Buzzers_KELIKING-KLJ-1625_C201041.html

[Psi]

And why do you think buzzers will be any different?

Mainly because crystal are a precision part. If the frequency/stability is off your product may have serious problems.
but if the piezo beeper frequency is a little off, or a little quieter than normal, it's not usually a problem.
If a crystal fails your product stops dead, if a beeper fails your product just doesn't beep any more.

The piezo beeper was just an example i ran into 3 years ago
This was the style/footprint of the buzzer i was ordering
https://www.digikey.com/product-detail/en/murata-electronics/PKLCS1212E40A1-R1/490-5262-1-ND/1992371

I dont think LCSC exited back then, or if it did i didnt know about it.

[wraper]

And why do you think buzzers will be any different?

Mainly because crystal are a precision part. If the frequency/stability is off your product may have serious problems.

Frequency stability was not a problem. They were mechanically damaged internally. Conductive adhesive between crystal and package broke.

[nigelwright7557]

"Save a penny, lose a pound"
"Buy cheap, buy twice"
etc etc

Learned my lesson years ago with ebay and/or Chinese parts.
Always buy from Farnell or RS Components now.

[ratatax]

Generally only use Aliexpress to get generic stuff and chinese-branded products and you're fine. I've had more problems with sellers sending the wrong item than counterfeit parts.
It's not a good idea to search for well known brands as it's too much tempting for sellers to make money this way.
The only branded stuff I bought on Ali was a box of 150 raspberry Pi's for like $5k, everything went fine but I checked it was an approved official retailer and with highly positive feedback

[Psi]

I've had more problems with sellers sending the wrong item than counterfeit parts.

Same.

[bd139]

Buying crystals from aliexpress sounds like a terrible idea.
As i said before, choose your battles.

I bought a ton (at least 800 from 20-30 different batches) of crystals from Aliexpress and tested the vast majority of them properly i.e. motional parameter testing. They have been 100% problem free. The only issue you are likely to get is that the normal distribution of the frequency isn't specified down to ppm and the load capacitance isn't specified like some manufacturers but you can trim that out as you would if you needed an accurate in circuit crystal. They are absolutely fine for MCU clocks if you don't have precise long-term timing requirements which is what they are designed for. I managed to bastardise them into some pretty excellent crystal filters.

Interestingly the 100MHz no brand 5th overtone ones I bought for $3 were better than the commercial one I paid $30 to have made.

The trick with Aliexpress is know what the risks are and buy accordingly. For me that's don't buy anything that might kill you. The rest is fair game. The only risk is waiting because if it's a turd, meh you've lost $1 or so. 

[nigelwright7557]

I have found some Chinese stuff is ok and some not.
My stance now is not to buy semiconductors but passives seem to be generally ok.
I ordered some 0.2" pitch capacitors off Ali Express and when they came they were 0.3" so didnt fit my pcb !
So on my next pcb made the pitch 0.3".
When I ran out of caps I bought some more more 0.3" and when they came they were 0.2" !!!!!
I think someone needs to sell the Chinese a ruler.
I complained about the narrow caps and was told to ask a "proper" engineer about them and could I not force fit them !
In the end Ali Express butted in and refunded me.

I bought some mosfets off Ali Express for an amplifier.  It powered up fine but when I unplugged my soldering iron it blew up.
The glitch down the mains must have got in to the amp power supply and pushed the mosfets into breakdown.
So this time I bought some from RS Components and the yare still working (despite me trying hard to blow them) for 18 months.
The Chinese have a habit of cutting corners and use smaller dies than the original which messes with parameters.

[Quarlo Klobrigney]

I bought some 25 or so 100 qty packs of 1% resistors last year. 50% of the 25 packs were 20% off value, in other words, the 100K pack ok, 1M pack 20% off tolerance. And so on. I had to verify the error to Alibaba with a picture of the defective resistors, one by one per pack value with the accompanying Fluke LCD screen before I was granted a refund.

On another order that came up short, Phoenix connectors at 20 pieces were at 14 pieces. I had to show a picture of a bag with only 14 in it and the label of 20.

Now how does one send a picture of completely missing goods. I'd like to know.

[bd139]

I just charge backed aliexpress when they did that with the "prove it never arrived" and they blocked my account 

Fuck 'em!

[SilverSolder]

[...]

Now how does one send a picture of completely missing goods. I'd like to know.

That problem is what "Tracking" is supposed to solve?  -  mind you, it doesn't always.   Sometimes the post office messes up the delivery, it gets marked as "Delivered" but ends up at someone else's house...

[GavinHemmings]

I have a lot of products from aliexpress and I have no problems with this.

[wraper]

I have a lot of products from aliexpress and I have no problems with this.

Then you are either very lucky or simply clueless about what you got.

[wraper]

Buying crystals from aliexpress sounds like a terrible idea.

With just a bit more you can get crystals from a major Chinese brand with a clear English datasheet on LCSC, still 90% cheaper than a western brand on Digikey.

The problem is some people buying from Ali are looking into shaving off the last 1/10 cents and race down to the absolute bottom.

The 10/90 rule is in most case correct. I'd certainly pay 10% the price for 90% the quality, but at that point, I've already saved 90% of the money and there's no need to risk stepping in the territory of sub-10%.

Greediness has to have a limit. Otherwise sooner or later some idiot is going to put a fucking capacitive dropper in a phone charger. I'm not even joking if you watch Big Clive's teardowns.

They were not THAT cheap. And I can buy similar crystals from LCSC for 30% of the price I bought those for.

[Koen]

12 years on Alibaba, about 10kEUR / year, zero issues, very happy overall. Just got my first bait and switch : https://www.eevblog.com/forum/manufacture/tewaycell-li-polymer-batteries-scam-bait-and-switch/

[nigelwright7557]

Got 2 AD9220 a2d converters from Analogue Devices.
Bought 2 from Ali Express.
First pcb I used an AD device and got it working fine.
As an experiment I tried the Chinese device and couldnt get full speed out of it without lots of data noise.
I should know better by now than to risk Chinese parts.

[Edward3121]

这样的元件并不适合在阿里巴巴（aliexpress）或者ebay上购买。因为这两个网站上的卖家鱼龙混杂。从这里买到的元件可能是“能工作”或者“可以用”的，但是长期使用或者用于极限情况时候会出问题；当然也会有很大几率买到不能用的器件。因为卖家为了利益，卖的元件是假冒的、翻新的、打磨的、甚至是工厂筛选下来的废料重新包装的。但是这不代表中国器件（chinise parts）是不行的，只是没买到好的而已。
提供一些建议（我自己的经验）：
1.在阿里巴巴（aliexpress）或者ebay买元件（包括有源和无源器件），要有一定心理准备，因为可能有无法工作的。
2.经过自己尝试或者朋友推荐，确定一些比较可靠的卖家，尽量在这些卖家中买。
3.如果一定要在阿里巴巴（aliexpress）或者ebay买元件，而且是芯片类型的，不要相信所谓“全新”、“散新”、“原装”这样的字样，很多都是假冒的或者是翻新的。要买“原装拆机”的，也就是从旧的PCB上拆下的，没有经过其他处理的，这样能保证是真品。
4.建议去元器件零售商购买元件，比如贸泽电子、digikey、深圳立创商城（SZLCSC，中国）等等，价格会略高一些，但是能够保证品质。顺便说一下，深圳立创商城（SZLCSC）有很多中国产的（chinise parts）器件，质量也是有保障的，价格也很实惠。

[VK3DRB]

A client commissioned a contract manufacturer in China to make a device I had been developing. Part of the device has two brand-name 100k 0.1% 0402 resistors used as a voltage divider from a precision 2.500V voltage source down to 1.250V used as a voltage reference. They built 100 prototypes of the boards, but there were about 10 failing boards with the same error in firmware - some failing straight away and others failing after a after a few weeks of testing. Found out the cause of the error: Some of the 100K resistors were out by up to 1%, with one measuring 97k... 3% low! The values were all over the shop.

The manufacturer's excuse was they might have had the temperature profile on their reflow oven set a little too high. I suspect this is complete and utter and it is more likely the manufacturer just had used cheapo generic resistors from the likes that you would see on eBay, AliExpress or a back alleyway behind the Shenzhen market for "a-dime-a-dozen". Even 1% resistors would not have that amount of variance from the same reel.  I have never seen resistors going low with too much heat. Going high with excess heat - maybe -  but there were no other issues on these boards that were quite complicated with many parts including BGAs.

[SilverSolder]

[...]
Now how does one send a picture of completely missing goods. I'd like to know.

Take a picture of your empty mailbox!   

[nigelwright7557]

"Save a penny, lose a pound"
"Buy cheap, buy twice"
etc etc

Learned my lesson years ago with ebay and/or Chinese parts.
Always buy from Farnell or RS Components now.

Just out of interest I bought a couple of cheap AD9220 a2d converters off Ali Express.
I also got a couple of samples from Analogue Devices the manufacturer.
The AD genuine one worked ok upto 10MHz.
The fake part struggle from about 8MHz and was very noisy.
So it seems I dont even take my own advice !

[Psi]

Best advice for Aliexpress,

- Order by price
- Ignore the bottom 25%

That will cut out a lot of junk which is too good to be true.

[BravoV]

Really boring reading this kinda whines everytimes ... a typical noob online shopper.

Its like a noob, who bought a brand new iPhone for 10 bucks  in the alley with shady guy, and then whines alot that got cheated. 

Worst, and then cursed and accused the people who live in the whole neighborhood or the whole block are cheater and evil. 

[BravoV]

"Save a penny, lose a pound"
"Buy cheap, buy twice"
etc etc

Learned my lesson years ago with ebay and/or Chinese parts.
Always buy from Farnell or RS Components now.

Just out of interest I bought a couple of cheap AD9220 a2d converters off Ali Express.
I also got a couple of samples from Analogue Devices the manufacturer.
The AD genuine one worked ok upto 10MHz.
The fake part struggle from about 8MHz and was very noisy.
So it seems I dont even take my own advice !

As the old saying, fool me once shame on you, fool me twice ... what a moron am I.

Sometimes you just can NOT fix stupidity, even your own.

[dietert1]

Why somebody needs to buy parts really cheap? Probably because there is a lack of income. Maybe the reason for the lack of income is using unqualified parts in the past and spending to much time on fixes.
I mean there are people who started this as a student (when their work could not yet generate income) and missed to change their habits later. It's not your work to shave off some pence from a BOM or is it? I am trying to do my work instead.

Regards, Dieter