I Wonder about some of these CHEAP PARTS from Overseas, So.....

Electronic parts are inexpensive so why not get perfect parts instead of cheap ones where many are faulty?
Hey, Sharp is selling an 8K TV for $133,000. Maybe I can buy a cheap Chinese copy for only $33,000 or $67,000 and maybe I will be lucky it will work properly?

Where is that photo of a cheap Chinese car that got its rice-paper fender crumpled when it hit a bicycle tire?

audioguru said:

Electronic parts are inexpensive so why not get perfect parts instead of cheap ones where many are faulty?
Hey, Sharp is selling an 8K TV for $133,000. Maybe I can buy a cheap Chinese copy for only $33,000 or $67,000 and maybe I will be lucky it will work properly?

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For this very reason, I never buy anything expensive from China.

GORDON ROBERTSON said:

Zahri, just to clarify my position. Although I stated that 75% of the parts I've bought fromChina fall short in some way, I would have to say that the vast majority say 85% of that 75% were perfectly acceptable and given the massively discounted prices represented good value for money.

From post #18 15% are perfect, from this post 85% of the 75% are very good, therefore 15% + 63.75% = 78.75%

More than 3/4 of all the Chinese components I've bought have been acceptable to me and have represented good value for money.

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My experience with Chinese components is similar to yours.
My comment was not about your post only, it was about this thread and the other thread. I find it surprising to see such different opinions about Chinese components. I still have this theory that the advice people give is too strongly biased by the name of the OP.

zahwi said:

My experience with Chinese components is similar to yours.
My comment was not about your post only, it was about this thread and the other thread. I find it surprising to see such different opinions about Chinese components. I still have this theory that the advice people give is too strongly biased by the name of the OP.

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I think that perhaps people make up their minds based on only 1 or 2 good or bad experiences. My perspective is based on perhaps 30+ purchases over a 4 year period. You quickly learn the bad ones and don't go back.

Besides these Chinese ones I just got, I have 5 other IRF640's, All in different Batch Numbers, purchased at different times.

Doing a Quick Test in a simple circuit and Comparing all these 5 Batches, they all respond about the same.

The Chinese ones DO NOT.

With all Biased the Same, This Chinese appears to have a different Gain.
But they stand up to Continuous Current Ok, without overheating.
(About the same heating at a Specific Current as the other 5 batches I have.)

I don't know about Maximum Voltage Yet and that is more if a concern for me.
And I will test that later.
On the two parts I used, neither one showed signs of overheating so I suspect it was voltage related.

During several years I've ordered from China 40-50 items. With some of them it was clear that they were second hand, either returns or rejects of manufacturer. I'm convinced that it's true for most ebay dealers in China. I suspect that it is also true for electronic components. With electronic components it is hard to detect the defects.
I'm like most people who buy cheap stuff, we hope that the fault the product has isn't a problem for us and that make us feel like winners.
For me there is another reason to buy from China. I feel good not to give my money to a sales-person that uses it to buy our democracy.

chemelec said:

The Circuit I am using is WELL UNDER the Requirements of this Mosfet.
It Should NEVER Fail in the circuit I am using.

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If your running the coil unclamped, don't forget to check avalanche energy. That might be something they miss.
Probably worst without a plug to fire.

It was NOT Unclamped, It was running a Spark Gap.

I have had a few problems with Chinese Transistors. Like chemelec they all worked, but not quite as specified in the supposed manufacturers data sheet. One mosfet had different pinout and higher input capacitance than data sheet. I've had the pinout problem with bipolar transistors too, with 2n2222. The Chinese 2n3904's all had hFE > 300, the data sheet maximum is 300, in most cases though this isn't a problem and even anadvantage in some cases. Diodes have mostly been good but I got a box of 1000 1n4007 that all worked, my only complaint was that their leads were thin and made of a soft metal ( in comparison to regular sources ) The thin & soft metal leads apply to quite a few Chinese components including IC's.

As far as electronic components from China are concerned I cannot comment on that as I can't get the best quality components to work properly.

I can comment from an engineering perspective though having worked with race engines & race cars my entire life.
The problem with China is that they have had no engineering practice & copy everything & as long as it looks the same it is the same.
With good engineering there is a golden rule, Make It, Break It & Build It Better so it doesn't break.

I have stood at Lathes & Milling machines & had my workshop full of smoke coming from steel that is full of impurities from China, there lack of Metallurgy practices or lack there of is a very worrying thing considering what they are selling to the rest of the world.
Who has owned a Chinese tool that has been any good & or has lasted as expected, not me!

I do however think that the new 2016 model car attached below is an improvement over the 2015 model attached as well.
Cheers

chemelec said:

It was NOT Unclamped, It was running a Spark Gap.

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chemelec said:

It was NOT Unclamped, It was running a Spark Gap.

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OKAY, just asking. Most of your circuits I've seen on the web are unclamped. So for lack of a schematic I guessed this one was as well. Good luck.