Relays are one thing that you notoriously can't trust what it looks like. Yes, the one your friend bought on Amazon was probably also junk, but you should definitely buy components like this from a reputable vendor unless their application is absolutely trivial.

Rossmann has made all kinds of videos about this. Be careful out there.

https://youtu.be/B90_SNNbcoU

Err, 32 volts putting 64 watts into a dummy load just to get 2A to test a fuse? For a second I was wondering if I was watching electroboom.

It could be visually the same product but actually have different safety implementations

It could. But why would it?

Because what's stopping me from getting the same box and putting cheaper components and skipping all quality assurance and undercutting the original? Or even worse, taking the quality control failed items and selling them as working.

Is it unlikely? Maybe, but also it has happened enough times that it's probably worth paying attention here. Relevant on today's front page https://news.ycombinator.com/item?id=44638580

You misunderstood my point. Why do you actually think there are better quality components for $12 on Amazon than $4 on Temu? There's no accountability on Amazon either, so why would they care at all either and give you better stuff? Just to be generous?

There's definitely _more_ accountability on Amazon.

That's news to me. People are selling counterfeit everything on Amazon left and right, but somehow the people selling no name remote controlled relays are making sure they deliver a quality product. Interesting.

Active electronics is one are you need to be the most careful. Pop that cheap relay open and look at the components - ten to one, they'll be completely potted in opaque material that hides the fact it's using an underrated thyristor. It'll work... as long as you don't push too much current through it. It might also catch fire.

You can't even trust what's printed on the ICs. Seriously, look into chip counterfeiting, it's a real problem.

That's why active components from Digikey and Mouser are so much more expensive than what you see on Amazon or eBay. They can trace the components back to the fab where they were made. You pay more, but you know you're getting what you ordered.

I got what I ordered. A cheap remote controlled relay. That works. Do I expect it to be waterproof? No. Do I expect it to handle it's max rated load? Maybe, I'd check how hot it was after 10 minutes.

Do I trust it to work safely in my use case? Yes.

Other than people that buy from actual specialty stores, that's basically how buying anything works these days. You use your best judgement and continue on.

There is a place for cheap, untracked components. A hobbyist being able to pick up a bag of op amps for a couple bucks is great, even if sometimes they're not actually the part number they say they are. It's just the risk you take.

When you use counterfeit power components like SCRs, the risk you take is burning down your house with your family still inside.

Hey, it's your call. You're free to use what you like. Just don't say we didn't warn you.

Millions of those 'counterfeit' components are sold inside millions of Amazon products every month to US households. Don't go warning me, I at least have a clue of what I'm doing and what to watch out for. Go warn every neighbor you have buying $20 junk on Amazon that includes the components I'm using for a specific small hobby task.

It's alarming that people still consider Amazon a good place to buy electronics.