Measuring the characteristics of some cheap J113 / 2SJ113 n-channel JFETs I bought, so I can match them / divvy them into bins.

Put #15 of 20 into the JFET test circuit, and the power supply's current limiter kicks in ... whoops. Did I have it turned around so I swapped the terminals? Nope...

Take a peek at it. Slightly different marking. Still "J113", but the factory/date code is different. Put it in the component tester... it's a PNP BJT transistor, not a JFET at all, and with a pinout completely unsuitable for the JFET test circuit. If it had been in for more than a second, it probably would have let the Magic Smoke out.

Oh, #AliExpress sellers, where would #hobbyist #electronics people be without you? Somewhere with less excitement in their lives, I guess.

#MagicSmoke #Chinesium #fake #remarked #component #transistor #JFET #BJT #J113 #hobby

Electronic component scams: some companies are remarkably open about it.

If you buy components on AliExpress or similar online markets, you're probably already familiar with getting faux goods. If you're lucky, it's a clone of the actual part you wanted (transistor, opamp, whatever) with similar specs. If you're less lucky, you get a part that's the same general type, but not the one you wanted - order a transistor with particular characteristics, but receive another transistor type entirely, that doesn't work the same way.

And of course, if you're truly unlucky or you buy the cheapest listing you can find, you get a package with a completely random bit of silicon in it (order a JFET or MOSFET, receive a BJT, possibly with a different pinout...) or even a package with no actual electronics in it (receive a DIP package with proper leads on it, but cut it open and the leads aren't connected to anything, and there's no silicon die in it at all).

I happened to see this listing on AliBaba, the wholesale / manufacturer site related to AliExpress:
https://www.alibaba.com/product-detail/Screen-printing-TDA7729-TSSOP-28-Audio_1601262782430.html

If I read it right, they're offering to sell you a cloned part, but they'll silkscreen whatever fake info you want onto the package, so you can sell it as a genuine name-brand part. Or maybe they're offering to remark any component you want, who knows - I'm not going to contact them to find out.

Pretty brazen.

#electronics #hobby #AliExpress #fake #Chinesium #remarked #counterfeit #scam #silicon #component