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Old 15th Feb 2024, 2:26 pm   #1
Malcolm T
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Default No ident markings on BJT ?.

Should it be of concern when buying transistors that there are no ident markings on the case as to what it is ?
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Old 15th Feb 2024, 2:39 pm   #2
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Default Re: No ident markings on BJT ?.

It's not possible to answer that question without more information.
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Old 15th Feb 2024, 2:45 pm   #3
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Default Re: No ident markings on BJT ?.

Certainly.

The ideal would be to see a recognisable maker's logo, a familiar type number with the right suffixes for the package and environment options, along with a valid date code. But that still doesn't give you full comfort. The fakers are up to all of those things. Printing is cheap. What's inside could be the real thing, a reject, nothing at all, or something completely different - dead or alive. The only way to feel moderately comfortable is to know you bought it from a trusted distributor. No part is so cheap that there isn't someone faking it.

Some makers only put markings on prior to shipping. Parts would go out with Jedec numbers, with maker's house numbers or with customer's stock numbers on the same device. The unmarked parts may be these, or they may have been nobbled after encapsulation and before any individual post-wafer tests.

They might be fine, they might not. You have no way of knowing. If something works when you try it, that's a good sign, but you'd still like to know if all you get fit into the tolerance bounds and will last a proper lifetime.

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Old 15th Feb 2024, 2:59 pm   #4
Malcolm T
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Default Re: No ident markings on BJT ?.

Thanks for replies and your thoughts.
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Old 15th Feb 2024, 6:01 pm   #5
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Default Re: No ident markings on BJT ?.

I have never seen a transistor with no markings on the case, I personally would be suspicous of it/them. I woud ask the seller to explain their source and why no markings.

Using a modern component tester/transistor tester you could test it to see if it has good junctions and if the pinout is as expected for the transistor you expected, also if its gain is in the right ballpark etc, none of this of course proves it is the correct transistor but should help to indicate if the transistor should at least be functional.

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Old 15th Feb 2024, 6:37 pm   #6
Malcolm T
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Default Re: No ident markings on BJT ?.

I,m waiting for a reply , it could be in the photo of the component but i have my doubts .
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Old 15th Feb 2024, 7:16 pm   #7
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Default Re: No ident markings on BJT ?.

The little hand-held component testers are decent enough at identifying pins and measuring Hfe, but they tell you nothing about voltage and current ratings, so you're left open to 'smoke events'

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Old 15th Feb 2024, 7:29 pm   #8
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Default Re: No ident markings on BJT ?.

It's trivially easy for dodgy suppliers to mark components with anything they like, including completely unrelated types and fake manufacturer's logos. You can't tell much about components from what's printed on them.

Legitimate manufacturers sometimes supplied unmarked devices to bulk customers, and overstocks or remaindered parts do sometimes turn up on the surplus market. Motorola transistors with just the 'M' logo often turn up, as well as parts only identified with meaningless house codes.
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Old 15th Feb 2024, 8:44 pm   #9
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Default Re: No ident markings on BJT ?.

Back in the 1970s electronics magazines, surplus electronics businesses such as Bi-Pre-Pak listed mixed packs of unmarked/untested transistors. These were probably manufacturer's rejects but were possibly OK for hobbyist use. At least back then they were probably genuine parts.

Nowadays I'd give any unmarked parts a wide berth, it's not really worth the gamble. I can't say I've seen any semis being offered as unmarked in recent years.

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Old 16th Feb 2024, 2:33 pm   #10
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Default Re: No ident markings on BJT ?.

Yes it's ages since bags of off-spec unlabeled transistors and diodes were sold to unsuspecting hobbyist types...

Anyone remember the red/white/green spot transistors sold for ten-and-sixpence in the small ads of early 1960s Practical Wireless??

Given the ubiquitous availability of transistors from reputable suppliers at sensible prices, the idea of buying unlabeled parts from who knows who/where would not seem a sensible path to tread.
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Old 17th Feb 2024, 10:58 am   #11
Malcolm T
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Default Re: No ident markings on BJT ?.

Looks like i will not be buying from that shop in Spain as i got no reply !
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Old 17th Feb 2024, 8:27 pm   #12
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Default Re: No ident markings on BJT ?.

Quote:
Originally Posted by Malcolm T View Post
Looks like i will not be buying from that shop in Spain as i got no reply !
I am suspecting that you have had a good escape! Just what are the transistors that you were looking to buy? Unless they are some deeply-obscure types, surely there are mainstream suppliers [with proper accreditations for their supply-chains] that could provide.
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Old 18th Feb 2024, 1:36 am   #13
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Default Re: No ident markings on BJT ?.

Quote:
Originally Posted by Philips210 View Post
Back in the 1970s electronics magazines, surplus electronics businesses such as Bi-Pre-Pak listed mixed packs of unmarked/untested transistors. These were probably manufacturer's rejects but were possibly OK for hobbyist use. At least back then they were probably genuine parts.

Nowadays I'd give any unmarked parts a wide berth, it's not really worth the gamble. I can't say I've seen any semis being offered as unmarked in recent years.

Regards,
Symon
Around the same time period, a Electronics shop here in Perth WA had two "Lolly jars" at the checkout, one with "cleanskin" NPN transistors, & the other with PNP ones.

They completed the "sweet shop" vibe by putting your selection/s into the same sort of small white paper bags that you might have carried away your "gobstoppers", musk sticks", "Choo-Choo bars" or whatever.

I never had much to do with the PNP ones, but the NPNs were useful just about anywhere you might otherwise use a BC107 or 108.
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Old 19th Feb 2024, 9:02 pm   #14
Malcolm T
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Default Re: No ident markings on BJT ?.

2N2222 s , and just some usual assorted components . I wont be doing un-marked stuff from unknown supplier .
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Old 19th Feb 2024, 9:47 pm   #15
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Default Re: No ident markings on BJT ?.

They can be worth buying for jellybean type applications if the seller seems trustworthy and the price is low enough. You might as well just buy Chinese 2N2222s or 2N3904s though, which are cheap enough. Jellybean transistors are almost never faked as there isn't enough money to be made from faking them.
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Old 20th Feb 2024, 12:11 am   #16
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Default Re: No ident markings on BJT ?.

Never faked, but a Chinese yellebean likely contains a crystal that meets the average specs of tens of jellybean types in a housing with the stamp of the requested jellybean type. Nothing wrong with that, but it could be that it barely meets the spec for one type yet amply the spec for another type.
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Old 20th Feb 2024, 10:30 am   #17
Malcolm T
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Default Re: No ident markings on BJT ?.

So i,m now checking off jellybean components from the big suppliers , thanks for all your help.
Available in the thousands and millions in regular old style packages and also smt etc should keep me for a while.
Easier to order here rather than from Uk what with all the idiocracy to deal with !
But in Britian the web site shopping experience is superior to Spain .
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