It’s rather amazing how many electronic components you can buy right now are not quite the genuine parts that they are sold as. Outside of dedicated platforms like Mouser, Digikey and LCSC you pretty much enter a Wild West of unverifiable claims and questionable authenticity. When it comes to sites like eBay and AliExpress, [hjf] would go so far as to state that any of the power transistors available for sale on these sites are 100% fake. But even small-signal transistors are subject to fakes, as proven in a comparison.
Found within the comparison are a Mouser-sourced BC546C, as well as a BC547C, SN3904 and PN2222A. These latter three all sourced from ‘auction sites’. As a base level test all transistors are put in a generic component tester, which identifies all of them correctly as NPN transistors, but the ‘BC547C’ and ‘PN2222A’ fail the test for having a much too low hFE. According to the generic tester at least, but it’s one red flag, along with the pin-out for the ‘BC547C’ showing up as being inverted from the genuine part.
Next is a pass through the HP4145B curve tracer, which confirms the fake BC547C findings, including the abysmal hFE. For the PN2222A the hFE is within spec according to the curve tracer, defying the component tester’s failing grade.
What these results make clear is that these cheap component testers are not a realistic ‘fake’ tester. It also shows that some of the fake transistors you find on $auction_site are clearly fake, while others are much harder to pin down. The PN2222A and 2N3904 used here almost pass the sniff test, but have that distinct off-genuine feeling, while the fake BC547C didn’t even bother to get its pinout right.
As always, caveat emptor. These cheapo transistors can be a nice source for some tinkering, just be aware of possibly wasting hours debugging an issue caused by an off-nominal parameter in a fake part.
I never encountered a fake part in my life… or, more likely, I never noticed. :-D
Admittedly, I don’t build the most complex of circuits. I’m sure all my builds are riddled with fake parts that work just kinda well enough.
Most people won’t when they use them as a switch. When you build an amplifier, or are building a thousand of the same products, you will notice.
I’ve read the article, and find the analysis to be a bit too simplistic. While I believe the conclusion about which part is genuine and which is fake is likely correct, I would like to see a more rigorous comparison. For example, I would compare several of each type, and compare the results to the datasheet. As these transistors are made by hundreds of different companies, there are bound to be differences. Even the pinout changes from brand to brand, sometimes.
I have a few samples of each transistor and I’ll be doing a follow-up article at some point . but right now I’m waiting for genuine parts of each to make individual comparisons. say , 10 measurements of potential fakes vs 10 samples of genuine parts.
Fair enough. I’m aware how much work it is, and I hope this HackaDay fame gives you a reason to continue your quest. :)
Same. I have never dealt with this issue despite ordering from AliExpress and Tayda almost exclusively.
Unreal for me to believe that. I have a few hundred semiconductors from AliExpress which are all fakes. I have also bypassed potential purchase of thousands of fake devices from single transistors to jelly bean SSI TTL and CMOS to MSI logic to LSI logic. Most offerings in some categories are fakes with actual parts very few and far between.
I first encountered counterfeit IGBTs when our supposed 1200A modules were shorting out well below nominal current in testing. Some post mortem examination reviled the modules were 800A relabeled 1200. I started using gate signature analysis to weed out these modules.
Counterfeiting $300 modules at least makes economic sense, but these small signal parts on an auction site hardly seems worth it. Is it just for the chaos!
They could be test rejects, so there’s not much effort in selling them.
That honestly makes the most sense. I don’t think anyone is going to take the time to counterfeit most common components
If not counterfeit, then salvage. There are parts of the world where labor rates are so low (and any kind of revenue, so dear..) that even SMTs are sorted. Other parties might buy those residues in bulk, then remark them as marginally more valuable new parts. Usually the leads are obviously (bright dip) tinned, but apparently they’ve innovated into matte tin (etch, or strip and plate?) so it’s hard to tell based on that.
I have encountered fakes, many years ago. We were working on a project, I forget what and for whom, but a manager wanted prototypes fast, and insisted we buy a hard to source part from some broker he had found online.
Yep, they were fakes. We had to wait for our distributor to source the genuine ones and then rework all the boards. When I have encountered the same “hurry, hurry, rush, rush” from subsequent managers, I have told them that story, and explained to them that there’s an even chance those parts they want to order (at horriffic markups) from the broker have a not insignificant probability of being bogus. If they want to take the risk, it’s fine with me, but they have been warned.
If they want to take the risk, it’s fine with me, but they have been warned….. if your manager insists on using fakes you should seriously think about leaving and getting another job IMO. I had a toxic manager once who tried to get me to do all sorts of really stupid pointless tasks and, worse still, finish off his own shitty workmanship whilst he went on holiday. Having said this, the alternative is to stay and endure a humongous ego shattering roller-coaster as you try and steer an even keel. Nautical metaphor intended.I have never encountered counterfeit small-signal devices – although not having tested them – usually my projects have quite relaxed specs.
But for the power devices, Chinese LM323 regulators were POS and not even regulators, TIP102 transistors gave up the ghost at 1A load as did IRF 9530.
No problems with the Digi-Key parts.
So I avoid Chinese power semiconductors.
power transistors are the worst. good luck finding a good 2N3055 on ebay or Ali. all of them are fake.
I’m apparently lucky my dad left me a few dozen of 2N3055’s and MJ2955’s when he passed away. All are from the 80’s, genuine, and have for sure been rigorously tested because they were high-end electronics components at the time. :D
Now I just need some project where I can use them, heheheh. ;)
Actually, I have projects enough, let’s not go there… :x
I’ve encountered what I think was a fake LM386 in a kit of a Pixie QRP transceiver (TX part was a simple oscillator, really).
Installing an LM386 from the 1980s (NOS) made the receiver work.
Anyway, the Pixie wasn’t great to begin with, but I was surprised that the 386 was not a “real” one.
“genuine” Chinese power (or other) semiconductors can be just fine. I haven’t had too bad of luck with LCSC though I think some of the generic DW-01 BMS chips I bought had much higher quiescent current than advertised. Pick your battles, if it’s critical to the design, stick with trusted distributors. For less important components or ones used well below their design limits, probably fine.
Sure they can. The counterfeit makers technically could do it, too.
Let’s just remember all the Famiclones from the past decades, they were of varying quality from bad to very good.
Chinese companies can work both very well and very cheap, I’d say.
The reason they produce cheap/for little money is to make profits, because they are told to do so (by western clients) and to enter markets not served well by the official sources.
Personally, I see no difference to US companies here.
Both of them are capable of omitting quality control, too.
I have found that nearly every LM308 op amp I have tried to buy has been a fake. Some times it’s even a dual option amp rebadged and then the seller just quietly refunds you with no apology or explanation. On the flipside, I have a bag of 2n3904s that I’m fairly sure are fake because their HFE is quite a lot higher than expected for spec and they actually sound really good in fuzz pedals so I have searched out more of them lol. Make sure you test your parts!
Try sourcing optocouplers, especially gate driver ones. Testing is incredibly difficult as you have to scope genuine part in action and compare to fake, then thermally stress them as often the fake works fine at room temperature but problems start at either end of operational range…
It’s sometimes easier and cheaper to design piggyback mod using similar part available from proper supplier than trying to weed out fakes.
Think of what you need in a particular transistor in an application, and you need to test to confirm those parameters — easier ones to test could typically be gain (hFE) — at high and low currents; leakage currents; current carrying capability (RDSON in MOSFETs); VTH in a MOSFET; and breakdown voltages (BVCEO, BVDSS). Fake or defective devices will fail one or more of these. More difficult is frequency performance, but — for power MOSFETs — gate capacitance is a good indicator also.
I think the 4145B can read all of those parameters but it’s a little limited (for example only 20mA @100V) but I’m looking forward to learning more
this whole article is the product of me trying to test that fake 547 and results not matching HP AN 315 which is a little cookbook of how to use this monstrosity
Brings back not so fond memories of the bad old days when we bought a bag of transistors or diodes from radio shack with the “u test them” warning. We used to call them floor sweepings. I remember once buying a bag of 20 diodes and three of them were good. Probably test rejects from the days of 60 to 80% yields.
Some things never change.
Just look LM338K on Ebay Ali all are wake!
I was making some VCOs for my synthesiser, using a circuit that ramps a voltage on a capacitor, which then discharges rapidly using a comparator and JFET. I bought some J201 small-signal JFETs from eBay.
I sent off to have the boards made, and I assembled a couple when they came back. I could not get the VCOs to oscillate reliably, and struggled to find something wrong with them. Checked all of the components religiously.
Then I put the JFET into a component tester, and I was surprised to see it say that it was an NPN transistor. The entire batch were the same.
How does anyone make any kind of profit making fake JFETs? They are only worth pennies each anyway.
I got stung on a couple purchases on EBay. MJ15004 & complement MJ15003. Shorted out immediately and took out other components. I popped off the tops(T03) to find the chips were < 1mm square instead of 2mm. Looked it up and fakes have the wrong labeling and can easily be wiped of with acetone. I was conned and EBay brushed me off. Mouser had the real thing.