Don’t get Burned by Cheap Semiconductors!

Last week I finished building an amplifier circuit board that will eventually be part of an SSB transceiver that I’m designing and building. After double and triple checking the board, I applied power… and heard a “pop” sound, followed by a little cloud of smoke. There was small hole blown out the side of the FET (Field Effect Transistor) on the board, and two of the resistors had been burned out–literally looking charbroiled. What in the world happened?

I checked the remaining supply of FETs that I had bought on eBay, and found something peculiar: My component tester indicated that these FETs (Field Effect Transistors) were actually showing as NPN type transistors (BJTs). (These are two very different parts!) To make a long story short, the FETs I bought on eBay were fakes! Someone had printed the part number of the more expensive FET parts onto a cheap regular transistor body, and sold them as FETs.

Here are some tips to avoid getting burned when buying semiconductors these days, in the age of chip (and semiconductor) shortages, and the resulting increase in scam artists using this as a way to make money.

Buy a component tester.

Buy an inexpensive component tester like this one on Amazon. (I don’t get paid for this suggestion). Or Google on “component tester,” and you will find dozens of options. Just get one! They mostly all do the same thing: You plug in a part, and it tells you what kind of part, and what the various values the part has. Here is a photo of a component tester showing a good JFET (Left) and one with the fake FET (Right).

If it’s too good to be true…

If some sellers on eBay are selling a semiconductor for $10 each, and you find a different seller selling the same item for 1/10 of the price: Be suspicious. Check the return policy to make sure you can get a refund. If you purchase a real bargain, be sure to check the parts as soon as they arrive. If they are fake, then immediately request a refund through eBay or Paypal before the return period is up.

Check the Photos

Let’s say you want to buy some 2SC1307 transistors. Google on “2SC1307 FAKE,” and you will see photos of legitimate versus fake 2SC1307 transistors, and other information on how to spot fakes. If the photos in the eBay ad match the photos of fakes, then steer clear.

These 2SC1307 transistors typically go for about $10 each. Before I was aware of the counterfeit parts scam, I ordered several of these for a really low price. I was going to use them for final output transistors for a linear amplifier that I’m building. It turns out that the transistors I received were bogus. They were functioning transistors, but when I put them in a circuit, they were only good up to about 5mHz, and not the 30mHz or higher that they should have had. They were fake. And after googling on “2SC1307 Fake,” I could see that my bogus transistors matched the photos on the known fakes.

Below is a photo from the web site https://dk7ih.de/fake-components-and-how-to-recognize-them/ which discusses fake parts. On the left is a “legit” 2SC1307, with the fake being on the right. The part on the right looks exactly like the “bargain” parts that I bought, and which turned out to be fake.

Not all cheap parts are scams…

I bought a bag of 1,000 2N2222 transistors for about $20. That’s a penny per transistor. And these parts work perfectly, and roughly match the specs of other 2N2222 transistors that I have bought elsewhere. But the 2N2222 is so plentiful, and has been made by many different manufacturers, so it’s plausible that this deal would be real. And I’ve used dozens of these with good results, so I feel confident that these parts are the real deal–or else they are such good fakes that it doesn’t matter.

Out of the six batches of bulk (i.e. more than quantity of 10 pieces) semiconductors that I have bought in the last 6 weeks, 2 out of 4 orders from eBay were fake (Fake FETs) and 1 out of 2 orders that I placed from Amazon were fakes. The orders that yielded good and cheap parts (FETs) were ones that had somewhat more obscure part numbers, like 2N5458, and BF245C. This suggests that the scammers are focusing on the most popular parts on the market.

Out of Spec Parts

Some parts sold on eBay and Ali Express, etc. may be legitimate parts, but way out of specification. For example, I bought several packages of 1,000 capacitors of different values on eBay, half expecting them to be junk. When I received the package from China, I tested a bunch of the parts. And while capacitors are commonly up to 10 or 20% different than their stated value, some of these bargain capacitors were more like 80% off! For example, one batch, the 100nF capacitors: actually measured as 55nF on the component tester. Another batch that were supposed to be 470pF, were actually: very close, at about 465pF. Sometimes ebay sellers will sell bulk parts that failed to meet manufacturing specs, but are still working parts.

Fortunately, there was very little variation within each bag of capacitors. The bag marked 100nF for example contained capacitors that were all approx 55nF. So I marked “55nF” on the bag, and used the parts according to the actual value shown by the Component Tester, and not by what was marked on the part itself. The capacitors worked fine–I just had to pay attention to the actual measured value of the capacitors.

Reputable Sources

If you need to be sure that you are getting non-fake parts, then you have the option of paying more, but almost certainly getting authentic parts. Some online sites that I have used and that are very reputable include digikey.com, mouser.com, and jameco.com. I have personally purchased many parts from each of these online stores, and never had a problem. There are many other reputable providers–these are just the ones that I personally have used. I had a positive experience when I bought some parts from Jameco. I only discovered a year later that half of the parts were wrong (not what I ordered). I sent one email to Jameco customer service, and that same day I was given a UPS overnight tracking number with the replacement parts, no questions asked. Now that was a good deal!

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