| General > General Technical Chat |
| i won't buy chinise parts from aliexpress or ebay |
| << < (6/22) > >> |
| cmrincon:
Hey! Check my new wear for manipulate mosfets :-DD |
| janoc:
--- Quote from: Marco on February 12, 2020, 08:27:27 pm ---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. --- End quote --- I don't know whether or not the neopixels have input protection but they are certainly easy to kill. Even if there is some protection, it isn't foolproof - it is usually just a pair of diodes and with a sufficiently energetic zap you will kill them or cause a latch-up, potentially destroying the part. It is certainly not a replacement for even basic ESD precautions. ESD mats are cheap, humidifiers and/or plants as well. |
| Circlotron:
--- Quote from: janoc on February 11, 2020, 07:00:28 pm ---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. --- End quote --- Good point. My example is I've bought several thousand "ST" M27C801 1Mx8 eproms from a particular supplier over the years. Upside is they are inexpensive, reliable, and only about 1 in 50 won't program fully. Downside is if you scrape off the paint there is some Chinese writing underneath so not made by ST in Singapore as per the outer layer, they take about 2 hours to fully erase and some won't even do that, and quoted access time is 100nS but in reality is closer to 1uS. But... they are reasonably consistent and quite good enough for my intended usage so I stick with them. I've bought a similar amount of SPW47N60C3 mosfets from the same supplier (TO-247 package) and early in the piece, when I would bend the leads at right angles they would crack and break off. Some were leaky and no functional, some even pressure sensitive in that they would stop working when they were clamped to a heatsink but come good when they were unclamped. Metal surface was all scratchy looking too, not shiny like a genuine one. Upside with these is when used well within their specs they were just fine. Some have been in daily use for 20 years now. Just been lucky I guess. |
| nigelwright7557:
Chinese businesses are like most countries, some good and some bad. The problem is do you just trust your luck or buy from reputable dealers. I got caught out a few times with bad ebay components and now just buy from RS Components and Farnell components. In the last 10 years only had 1 problem with Farnell and they had put wrong resistor in the packet. The packet had what I wanted on it but resistor inside was wrong. |
| vk6zgo:
Meanwhile, half century old CMOS gates have been working happily for, yes, half a century, in old equipment. Perhaps the "ancients" knew something you don't! ;D |
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