I'm on my second batch of bad Chinese MOSFETs. I have received good ones in the past... what to watch for:

PACKAGING!!! - The post showed SMD in Antistatic reels. They sent the MOSFETS in loose plastic bags.

Here was what they advertised:


Here's what I received


Tested 2:
They are dual N Mosfets with tied drains

First one I grabbed had both G shorted to both their S
Second - D/S shorted with no gate voltage in either direction!

UGH! Garbage!

 

They sent the MOSFETS in loose plastic bags.

Where did you buy them?

I've found that most Sellers on Ali Express have no knowledge of some/many of the products they sell. My experience is that when they say they'll contact their supplier and get back to you that they're just blowing you off and hoping you'll buy anyway.

The inexpensive logic level MOSFETs I've been buying from Ali Express are in the original tape, but they put that in a plastic bag. A reputable seller would put them in antistatic bags, but they're okay as long as they're in the original carrier.

I've bought CMOS chips on eBay from people who buy larger quantities and repackage and resell. I bought dozens of CMOS chips that came pushed into florists foam in plastic bags. It was too many parts for me to test (ESD damage doesn't always result in dead parts). I just put them in tubes and marked them as unknown condition and made a note not to buy from that seller again. I complained to the seller who did nothing other than say no one else has complained about packaging. That's when I stopped buying electronic parts from resellers on eBay. I'll only buy odd lots.

 

Instead of buying cheap junk, I buy genuine properly cared-for electronic parts from Digikey, and they have stock locally.
I support them so that they can continue.

 

Caveat Emptor. My wife is tired of my griping about chinesium parts. Yes, they are cheap! They take a long time to get here. They are undocumented. Often poorly packaged and damaged or lost in transit. 95% of the time they are good, either real marked new old stock or surplus parts or chinese generics. AliX will force the seller to reimburse for bad parts or shipments. So far, I have not encountered any scrubbed and remarked counterfeits. They are also sold through fleaBay and Amazon. I would not suggest using them commercially. They are strictly for my personal amusement.

 

This is not stocked by domestic suppliers. I got them through Aliexpress... I'm sure I'll get a refund... this is for a Hy2120 battery protection and is what's generally used for them. I haven't had any issues when they're packaged correctly. Just thought I would share.

 

Instead of buying cheap junk, I buy genuine properly cared-for electronic parts from Digikey, and they have stock locally.
I support them so that they can continue.

I bought 99% of my electronics parts from ebay, and think it's fine for 5% resistors, and some other stuff too like connectors.

But yeah there's nothing like getting the real stuff. From now on if I want anything above the most jellybean transistors or IC's, or cap's, or diodes, 1% resistors, etc, unless I'm really stuck, I will spend more and get it from a legit retailer.

Most my 1% resistors are 5%, my cap collection is bottom bin. The more I learn about AC analysis, the quicker I will find out how good/bad my silicon parts are, but I guess they are mostly bottom bin and knockoffs too.

 

I buy all my resistors from china. My 1k 1% 1/2W metal film resistor grabbed out of the bag measures 1006Ω. At $1.36/50 I'm satisfied. 90+% of my parts actually. I don't mind paying Digikey or Arrow prices but the shipping kills me on onesies and twosies. I don't want to wait to get the min $ order together to get free shipping. I'm cheap that way. I was buying all my parts from Arrow when they had free shipping. In a hurry Amazon delivers FAST but @ ~ 2X-10X the cost of the same exact part bought direct from china with slow delivery. FleaBay almost as bad and still slow delivery from china. I'll check fleabay prices just in case but it is rarely lower. Sometimes you do get lucky with fleabay. In a must have now situation I can usually find what I want on Amazon. If not 1st class mail from Digikey for small parts isn't too awful bad.

 

I bought a big lot of assorted resistors (thousands of bags with 10-20 resistors) that went with some kit on eBay about 15 years ago. I suspect they're from China. The leads are thinner than usual and are a pain in the a** to insert into breadboards.

 

I hate those and I avoid them when possible when we're doing labs... My favorites are the 1/2 watt old brown ones for breadboarding. I know the school buys from Digikey so it's not just China on those. They would be fine for soldering.

 

I bought PIC16F73's on Ali because they were cheap! Stateside they're $3 each on Ali only 50 cents. They did work but I knew they were counterfeit. The ink color on the part # was different and the pins were straight up and down instead of fanning out. Can't trust them. If they fail in the field we're in big trouble. Also bought ISD4003's. They did work but didn't even have a part # printed on them! If you use semiconductors for business products, stay with a distributor. And yes, the leads were thinner on both IC's. If I bent a pin, it would snap off when I bent it back.

 

That reminds me that I need to check I/O strength on some Arduino Uno's I bought on Ali Express. One had me chasing my tail troubleshooting until I realized that the outputs weren't capable of sourcing the current they were supposed to. I had to insert some CD4050 because the Uno outputs were so wimpy.

 

Never ever use these undocumented parts for critical use!!!! Use a reputable authorized reseller or go to the manufacturer for sources... good and inexpensive components can be sourced from China as well as any other country but there are some questionable counterfeiters out there also. I have had good luck buying from a site called LCSC they are similar to Digikey and the packaging is always correct and sealed in Antistatic bag on top with dessicants. They charge a little more for their services but so far they are 3 for 3. The advantage is that they stock a lot of product you can't get here... like $0.04 microcontollers (6 pin, 1K word, OTP). Again no point in trying to use them for cricital use... but I have non critical uses for things like this.

I'm working on changing to the new Microchip AVRXMEGA3.. The new chips are price competitive with China and beefier. Unfortunately porting will not be simple and I will have to design new boards, programmers... etc.

I like that we have a choice and competition can keep pricing reasonable.

 

I support them so that they can continue.

i would agree with you , but there was a price tripling about decade ago and doubling about the year ago
??? has the € devalued 6x since the 2007CE about https://www.inflationtool.com/euro ← according to this gizmo it's about 15% less valuable -- so everything rest is the profit greed of the supply chain . . .
the very same UPS model that cost 20€ before can yet be found for 70€ today - but the discretes have surely had 500% mark-up

 

I can get a small reel of 3000 MOSFETs for $25 out of China... same ones through Digikey $250. Keep in mind Digikey has to make a living. It's like the iPhone all over again... $600-900 for a phone (made in China) and I've heard you can get the same thing in China for about $100 -150. Again if this was highly critical you just pay and mark it up... for hobby, novelty and non-critical usage - they perform very well and I even do testing to make sure they can handle the current they claim. I got a full refund for the bad MOSFETs took about 1 hour for them to reply.

 

Instead of buying cheap junk, I buy genuine properly cared-for electronic parts from Digikey, and they have stock locally.
I support them so that they can continue.

Buying "genuine" is not 100% either.
Some years ago, I purchased some thousands x BD139 transistors from an official parts supplier that will remain nameless. Before we got to use them, they sent us a message to say that batch had been packaged in reverse. I do not know how that all came about. Of course they replaced them.
And more recently, from another place, a whole batch of graphic LCDs were failing. Those were refunded as there was a known problem with the factory.
Mostly I use RS or Element14. Not the cheapest, but easiest.
Still, I buy a lot off stuff from Ebay and have had very few problems, and most off those were to do with packaging, not the parts themselves.
The times I have had problems with Ebay, like the laser engraver DOA, the seller has sent replacements or refunded the payment.

 

The leads are thinner than usual and are a pain in the a** to insert into breadboards.

Did the same starting out long ago. That's why I use 1/2W resistors now is because they breadboard well. 1/4, 1/8W don't breadboard well at all so they are for through-hole use if they can meet the power required. 1W can wallow out a breadboard so nothing else fits.

 

I've found that 1/4W resistors from the reputable manufacturers (Dale, Vishay, KOA, SEI, Yaego, Roederstein, etc) all work well in solderless breadboards.

 

Looks like an old topic. https://forum.allaboutcircuits.com/threads/resistor-lead-diameter-grumble.86500/

 

Looks like an old topic. https://forum.allaboutcircuits.com/threads/resistor-lead-diameter-grumble.86500/

How did you find that? It was almost two years before I joined and almost 6 for you.

That thread was short on details. Here's Yaego lead diameter info:

1/4 and 1/2 watt resistors have the same lead diameter.

#22 solid wire diameter is 0.645mm (0.0254inches).