General > General Technical Chat
i won't buy chinise parts from aliexpress or ebay
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:
--- Quote from: ratatax on March 22, 2020, 06:07:38 pm ---I've had more problems with sellers sending the wrong item than counterfeit parts.
--- End quote ---
Same.
bd139:
--- Quote from: Psi on February 18, 2020, 11:50:48 am ---Buying crystals from aliexpress sounds like a terrible idea.
As i said before, choose your battles.
--- End quote ---
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. :-//
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