Fake 2n3055's - Page 1
Forum section: electronics / beginners

author: lordvader88
author_rank: Frequent Contributor
timestamp: June 25, 2019, 05:51:13 am
content: I bought some cheap ones, assuming they shouldn't cost much anyway, and they are garbage. I lost 2 whose collector-emitter junc. fried under 1.5A in a homebrew PSU (that works good).And just now fried the base-emitter with 300mA I(col) on there for about 5 minutes. I wasn't looking at it when it happened, I just looked over and the output was zero volts. Vce was 10-20V iirc.I better test the PNP versions I bought too.I bought them last year, I should have checked them right and claimed for buyer protection for fake parts.

author: Dabbot
author_rank: Regular Contributor
timestamp: June 25, 2019, 07:49:33 am
content: Pop them open and take some pics. Where did you get them?https://www.eevblog.com/forum/repair/warning-fake-mj16012-transistors-on-ebay/

author: Yansi
author_rank: Super Contributor
timestamp: June 25, 2019, 09:15:03 am
content: Problem is, even the genuine ones are absolutely useless these days!!! The so small barely visible silicon die coupled with the steel case with zero to no good thermal conductivity makes the transistor useful only as a paperweight and even that would not be good enough.Ditch 2N3055, use TIP3055 (TO247). That at least, when kept within reasonable limits, works wonders.

author: amyk
author_rank: Super Contributor
timestamp: June 25, 2019, 11:25:00 am
content: You did heatsink them, right...?

author: strawberry
author_rank: Super Contributor
timestamp: June 25, 2019, 11:32:23 pm
content: good component metal tab should fry blue before going short/open or unsolder wires

author: lordvader88
author_rank: Frequent Contributor
timestamp: June 25, 2019, 11:53:20 pm
content: Yeah it was ok, was just warm at the time.What do real ones cost ? I just figured they are that cheap.

author: james_s
author_rank: Super Contributor
timestamp: June 26, 2019, 12:23:00 am
content: Real ones tend to be fairly expensive, they're vintage parts that are no longer made, modern versions should not even be called 2N3055 because they're not the same. Then you have all the fakes which are even worse. If you don't need a 2N3055 then use something more modern and readily available. Original 2N3055's that work in all the old designs made around them are getting scarce.The TO-3 package is generally considered obsolete these days, the parts still made in it are typically aimed at servicing old gear.

author: strawberry
author_rank: Super Contributor
timestamp: June 26, 2019, 06:19:08 am
content: TO-220 fits TO-3 heatsink

author: Yansi
author_rank: Super Contributor
timestamp: June 26, 2019, 06:30:32 am
content: TO247 fits too, and TIP3055 ain't nothing expensive. Costs about 1-2$ a piece from a reputable distributor.//EDIT: I see them even below $1 from a local distributor, when you buy a couple of them.

author: rstofer
author_rank: Super Contributor
timestamp: June 26, 2019, 03:13:14 pm
content: DigiKey sells the On Semiconductor version of the 2N3055 for around $6.40 each. I would expect those to meet all of the datasheet specifications. Floor sweepings from China? Not so much...Mouser doesn't carry them at all - obsolete.

author: rsjsouza
author_rank: Super Contributor
timestamp: June 26, 2019, 04:07:14 pm
content: Quote from: rstofer on June 26, 2019, 03:13:14 pmYes they do:https://www.mouser.com/Search/Refine?Keyword=2N3055

author: rstofer
author_rank: Super Contributor
timestamp: June 26, 2019, 04:49:11 pm
content: Quote from: rsjsouza on June 26, 2019, 04:07:14 pmI guess I shouldn't have filtered on TO-3. Yes, Mouser has them.

author: schmitt trigger
author_rank: Super Contributor
timestamp: June 26, 2019, 05:29:38 pm
content: From Mouser's page.....TO3 ??Someone did not proof read the complete listing.

author: rsjsouza
author_rank: Super Contributor
timestamp: June 26, 2019, 06:28:39 pm
content: Quote from: rstofer on June 26, 2019, 04:49:11 pmAlthough named differently, the Central Semiconductor part is a TO-3 as well (and in stock):https://www.mouser.com/datasheet/2/68/2n3055-1108522.pdfQuote from: schmitt trigger on June 26, 2019, 05:29:38 pmAlthough the photograph is of a TO-18, the Microsemi part is in fact TO-3:https://www.microsemi.com/document-portal/doc_download/6038-2n3055ne-datasheet

author: schmitt trigger
author_rank: Super Contributor
timestamp: June 26, 2019, 07:44:48 pm
content: I know, I know... My post was only about the photo not fitting the description, thus my comment that it wasn't proofread.

author: MagicSmoker
author_rank: Super Contributor
timestamp: June 26, 2019, 10:39:17 pm
content: It's not just the TO-3* package that is obsolete, so is the double-diffusion fab process that made it. Modern "2N3055" are almost certainly made with the epitaxial process which generally produces a faster transistor (due to lower junction capacitance) but one that is also less robust. Then again, if it's a cheap knock-off from China then it might very well be a 2N2222 die in a TO-3 package...* - now called TO-204AA, for dog only knows why.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: June 27, 2019, 02:32:56 am
content: Quote from: MagicSmoker on June 26, 2019, 10:39:17 pmThe original fabs died in the 80s, AFAIK; they've been epitaxy since then. Which means the average 2N3055 you get, will exceed its spec by 2-10 times or better, and you'll never know in which parameters until you test them a lot at a time. Or maybe you get some ancient relics!If you must have old fashioned packages, I wouldn't recommend anything older than, say, MJ15022 or the like. If you must have BJTs, newer On Semi parts have excellent specs, and will most definitely deliver the power and SOA they claim. They aren't at all expensive, considering how much faffing with alternative sources you are saving in the process!Even better still is using FETs in an SMPS, but that is a more advanced topic so I won't complain further in that direction.Tim

author: cvanc
author_rank: Frequent Contributor
timestamp: June 27, 2019, 01:27:22 pm
content: Interesting discussion. Somewhere around here I have a few marked '2N3055H' from decades ago. I never knew what the H signified - homotaxial, perhaps? I remember they cost a bit more than the non-H version at the time.

author: MarkF
author_rank: Super Contributor
timestamp: June 27, 2019, 01:37:56 pm
content: Quote from: Yansi on June 25, 2019, 09:15:03 amSlightly off topic question:Does anyone know where in its life-cycle the TIP-3055 is for new designs?

author: rsjsouza
author_rank: Super Contributor
timestamp: June 27, 2019, 03:21:40 pm
content: Quote from: MarkF on June 27, 2019, 01:37:56 pmThat depends on the manufacturer. TI's TIP3055 (the original) was obsoleted a long time ago, whileONandSTstill have them.

author: Yansi
author_rank: Super Contributor
timestamp: June 27, 2019, 09:49:39 pm
content: TIP3055 is still actively manufactured, I would not be afraid using it in a design.