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. :)
If you’re building an amplifier from a magazine or a published circuit or even repairing one, the hfe of the pre driver stages or even the outputs can be critical. The fake could show as bad oscillation or even blow, because the transistor isn’t built to handle the same voltage and current. In fact, the company I work for have just recently found a counterfeit part. It was a very expensive I.C. It would pass initial tests but fail on the final product tests, which cost us thousands to put right. We checked the rest of the stock and all were fakes when xrayed. They found the internal should also have been gold and the internal wafers or whatever you call them, we’re too thin. This happened because someone in purchasing thought it would be a good idea to purchase through a third party and probably an auction site, to save money. Unfortunately that was a few years ago and has since left, and left us with a massive bill and a backlog of strip downs, reworks and rebuilds. Sorry to digress and bore everyone.
Yeah i think as a bonus, testing multiples of the same product will point at the quality question. If they are all rather tightly clustered around a common but not ideal characteristic, that’s very different than if they are each one wildly different than the one before it. Poor copy vs poor fabrication.
I dabble a bit building modular synthesizers, and the havoc that a semi-working component can cause is not worth the trouble. I would gladly pay several dollars more on a BOM not to have several hours of my time wasted and stressed out.
One use for a BJT is to handle an exponential control voltage for a voltage controlled oscillator. With the ideal being a 1V/octave control in a range of several octaves. That is, if 0V is middle C, then 1V is an octave above that, and -1V is an octave below. With -7V to +7V being a usable range for a very high quality VCO, hopefully intonation is correct withing several cents at the extremes And +/-10V running towards the design limit for control voltages.
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.
Easy for me to believe :) There’s so many different ways to interact with this stuff! I never use aliexpress — if my collection is full of fakes then they came from jimpak 25 years ago — but
For example, if i’m using a small ‘signal’ BJT, i am probably using it as a switch. Probably more than half the time i’ve used one, it’s been on the output of a microcontroller’s GPIO. Level-shifting, or just isolating a small load (like a relay’s coil) from the microcontroller. I’ve made a very small handful of circuits where i take advantage of the in-between states of a BJT, and in those cases it’s such a voyage of discovery that i’m more surprised “a transistor does THAT??” than i am that this particular sample doesn’t match the spec sheet.
So tbh a few projects or comments i see here, i’m astonished at how much effort they seem to be putting into it, “didn’t you know you can use a single NPN to achieve that?” i am yelling at the screen. But i know if i posted my electronics diaries here, there’s a whole class of people who would not believe how primitive my use cases are :)
Easy to imagine people don’t run into the limits of fake / QC reject components. That’s why they ‘get away with it’ anyways.
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
Test rejects, lead-in runs on the factory (calibration batch), re-labeled surplus inventory (wrong part), recycled transistors picked by children on a dump site…
Basically it’s someone taking someone else’s trash and selling it.
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.
It’s not just about “quality control” or the lack of it, it’s about outright -FRAUD- which is a widespread CULTURAL problem in China. There are books and studies written about that.
Guess what country was at the very bottom of the long list in this study. “Rates of return varied greatly, from 14 percent in China to 76 percent in Switzerland.”
Civic honesty around the globe
20 Jun 2019
Honesty and selfishness across cultures
Rationalist approaches to economics assume that people value their own interests over the interests of strangers. Cohn et al. wanted to examine the trade-off between material self-interest and more altruistic behaviors (see the Perspective by Shalvi). They distributed more than 17,000 wallets containing various sums of money in 355 cities across 40 countries. In contrast to what rationalist theories of economics predict, citizens were more likely to return wallets that contained more money. The findings also reveal a high level of civic honesty across nations.
https://www.science.org/doi/10.1126/science.aau8712
Here’s one example that just affected their fellow Chinese. At least the perp was executed, but punishment is reserved for major crimes like this which make the news.
“The 2008 melamine scandal involved counterfeit infant formula adulterated with melamine (an industrial chemical) to fake higher protein levels. It affected over 300,000 infants, hospitalizing 86,000, causing kidney stones and failures in thousands, and resulting in at least 6 confirmed deaths. Economic losses exceeded $1 billion, but the human toll was immense.”
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.
Floor sweepings lol
From PolyPaks? :-D
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.
Just get your credit card company to fix it.
It’s not so much the modern components that are a problem. They are all fake on eBay and AliExpress We all know it. Those super low prices are all lies. That’s just how it is. It’s not that you have to sort through the fakes to find the real ones at good prices . They are ALL fake. So if I you want good parts, but from places like Digikey. (Like actually digikey, not their marketplace) If you want to waste time and money trying to save time and money, then go ahead and order from AliExpress.
The big problem is trying to source obsolete parts for repairs. That’s a nightmare and thees just so good way around having to sort through the fakes to find a real one.
You may want to detect fakes for more reasons than having sufficient functionality. For commercial products, warranty costs, liability risks, and regulatory requirements often demand that the parts are from a traceable, original source. These could also easily affect your employment status.
Fake or not, I never had the slightest problems with electronic components bought from AliExpress.
I’d rather not be scammed
This article brings back fond, and not so fond, memories of buying parts at Radio Shack a half century ago. The one I frequented in downtown Philadelphia had a VOM /transistor tester under the counter for the regular customers to use before writing up the invoice. Random Nobody’s were told all sales final, no testing.😎
Darn! I bought some J107 JFETs last year on eBay because they seemed to have been discontinued and Mouser, Digi-Key, etc. didn’t have them, and I left the eBay seller good feedback, without testing them. I have not used them yet. Now I wonder if they’re even JFETs at all, based on what others here have written. Obviously now I’ll have to rig up some tests before depending on them for an actual use.
Even Jaycar in Australia is selling TO3 cases which claim to be high cost, high power transistors when they contain tiny dies and fine wires.
Wow. I knew that fakes are a problem but I didn’t expect to see it in such basic and inexpensive jellybean parts as these!
I bought a few AD 797 op amps from EBay. They don’t conform to specifications. Beware Chinese op amps that purport to be performance devices