It's a 12 year old thread, man. Maybe that horse has bolted?
There's a lot of good advice on these forums. And some bad. But I should think that would go for any hobby forum.
I haven't found DIYaudio particularly cliquey or unhelpful... If you want some help perhaps try starting a new thread with your questions, or a wrong answer, that's sure to get you a response [emoji1787]
Your disappointment is not for newbies and new members only. Being over thirty years in the electronics industry, I noticed a gradual decline of availablity and an increase in counterfeits for the last ten years where the popularity of easy webshop purchases has replaced sincere physical shops in towns with dedicated staff to mine the desired parts from distibutors.
We cannot go back to the past so noticing not so genuine parts and ditto webshops is an usefull mark for others at any electronic level.
Even more, the skilfulness to select alternatives is presently not anymore at the level as I had aquired during study and experience.
Your confusion about suggested alternatives do I share. And it becomes even harder in time to extract the proper data from suppliers to share satisfying results. For the 2SB647 / 2SD667 -- 2SB649 / 2SD669 range I haven't found exact substitues, such are just not made anymore. Closest matches rely now heavily on local availablity. Markets differ substantiously between continents and even the closer UK-EU market differ or will increase to differ.
Most members on this forum are willing to contribute sincere to your question. Deviation and off-topics are always present, but the more narrow the question, the more precise the answer.
If it's green, and from Taiwan, is it more likely to be real?
2pcs - HITACHI 2SB649A / B649A Transistor - NOS | eBay
2pcs - HITACHI 2SB649A / B649A Transistor - NOS | eBay
Thank you for a response. I don't understand why transistors have such a short life-cycle. Where are the improvements? Why the need to keep reinventing the wheel with slightlyu different parameters? Seems so unnecessary and wasteful.
I want a genuine 2SB649A..
And why are people so anti-NTE? What's wrong wioth NTE? The NTE374 seems to be the closest to the 2SB649A I have found so far..
Mainly by commerce, patents, production methods, market demands etc.
Improvements need not to be in technical terms: if one can resell a package of primes and subprimes it can be / is more profitable. That is another thing indeed. We now live in a topsyturvy world.
There are abundant examples in the world which are unnecessary and wastefull, that's the human footprint.
I have not (yet) digged deeply in NTE data. People are mainly recognisable by opinions.
One can find green PNP bjt's in 70's / 80's japanese amplifiers. The made them green to distinguish PNP's from NPN's which was usefull in the production line in that time.
There is no garantee that current green bjt's are genuine pnp's as stamped with a partnumber on it. Consider it a casino with a possible jackpot.
If that horse had bolted. Why would I be asking the same question? Strangely that's how forums work. You know. Someone asks a question that someone else might have already asked. Unless of course you are suggesting that no one ever will come to DIY Audio ever again asking about 2SB649A. Is that what you are saying?
Because I think you should make that clear. Perhaps with a message such as 'dear diy audio member' please don't ask any questions about the 2SB649A because ubergeeknz has decreed that all questions about the 2SB649A have been answered. Thank you for your cooperation. I do hope DIY audio appends such a message to the welcome to new members asap. It will avoid any confusion about horses and transistors.
I think we should go one step further and no allow anyone to ask anything about electricity.
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Hi
This chap is in Taiwan. I trust Taiwan a bit more than China. He's been a member on ebay for 17 years. I guess these are real?
2pcs - HITACHI 2SB649A / B649A Transistor - NOS
Although.. more confusion.. 2SB649A-C
I wonder if that is different to 2SB649A
?
AAAAaaagh!
Or is it a 2SB649A.. do they all have a C on them?
What does the C mean?
Why is this not easy?
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The suffix "-c" point to the beta (Hfe) subdevision.
There are:
2SB649A-A low beta (eg 100 - 200)
2SB649A-B mid beta (eg 150 - 300)
2SB649A-C high beta (eg 250 - 500)
Exact specs to dig up in datasheets (not always easy).
Other manufacturers use colors (jfet's):
Y yellow low S
G green low-mid S
B blue high-mid S
V violet high S
Your supplier has the high beta bjt's available.
When ordered and received, check them with a beta-meter anyhow.
There are:
2SB649A-A low beta (eg 100 - 200)
2SB649A-B mid beta (eg 150 - 300)
2SB649A-C high beta (eg 250 - 500)
Exact specs to dig up in datasheets (not always easy).
Other manufacturers use colors (jfet's):
Y yellow low S
G green low-mid S
B blue high-mid S
V violet high S
Your supplier has the high beta bjt's available.
When ordered and received, check them with a beta-meter anyhow.
I hope to ease some frustation by giving you as much as appropiate answers as I can. Hopefully this 'other' section of the topic will end this way.
Regards to both/all.
I'm not sure how what I said has been interpreted this way.
All I was saying is, it seems a little pointless to dig up a long dormant thread and complain about its content. Whoever made the posts you refer to are quite probably long gone.
And, as you can see, there's a very helpful community here willing to help answer your questions. I'm new here too, and not by any stretch a pro tech, and have found people here very helpful.
All the best.
I just read an analysis about the recent dispute if a dress was blue-black or white-gold (Scientific American, september 2019 edition), dividing people in two about the true truth of relative perception and not able to accept another view, as ones own had to be the real true truth.
Given the workings of the ego (following a faint thread to the Minotaur's labyrinth), responses are driven by mechanics (instinct, emotion, ratio), fed by the senses (intuition-providence, sense, taste and smell, sound and vision), to be interpreted and made meaningfull through primitive syntheses (ego, mechanics, senses) and creative syntheses (awe, submission, polarisation, clearification), and expressed in likewise ways as primitive, magical, religious or scientific manners.
(Cough...)
Clues are intrinsic in the responses above in how to deal decent and civilised with them. And it is true a serious mountain to climb to decently respond, garde (*) and care for fellow dudes during the trip.
Once you're stuck in the belief the dress is white-gold or blue-black, you're polarised, say better framed, into a lockdown perspective which is not what is available from the top.
No matter if said things are valid or not, ones perspective is only a representation of reality, not the reality. Opinion is a result from experience.
Talking about experience. What are currently good representatives of B649/D669 bjt's? Anyone recently doing some research?
Today I was... eehm 'vectorising' a new supplier about the issues addressed in this topic as a counterweight in the discussion. Boy o boy, we've lost so much. It ended up with some but not all bc550/bc560's, arid supplies of bc489/bc490 (those were really awesome!), hardly to get proper bd139/bd140's and so on. And this the scatterous european continental stock only. American 2N's and oriental 2sa/2sc--2sb/2sd are not anymore as I've known them for years.
I'm an old man... and shifted from perspective completely.
(*) Hence 'garden': protect the abundency
Given the workings of the ego (following a faint thread to the Minotaur's labyrinth), responses are driven by mechanics (instinct, emotion, ratio), fed by the senses (intuition-providence, sense, taste and smell, sound and vision), to be interpreted and made meaningfull through primitive syntheses (ego, mechanics, senses) and creative syntheses (awe, submission, polarisation, clearification), and expressed in likewise ways as primitive, magical, religious or scientific manners.
(Cough...)
Clues are intrinsic in the responses above in how to deal decent and civilised with them. And it is true a serious mountain to climb to decently respond, garde (*) and care for fellow dudes during the trip.
Once you're stuck in the belief the dress is white-gold or blue-black, you're polarised, say better framed, into a lockdown perspective which is not what is available from the top.
No matter if said things are valid or not, ones perspective is only a representation of reality, not the reality. Opinion is a result from experience.
Talking about experience. What are currently good representatives of B649/D669 bjt's? Anyone recently doing some research?
Today I was... eehm 'vectorising' a new supplier about the issues addressed in this topic as a counterweight in the discussion. Boy o boy, we've lost so much. It ended up with some but not all bc550/bc560's, arid supplies of bc489/bc490 (those were really awesome!), hardly to get proper bd139/bd140's and so on. And this the scatterous european continental stock only. American 2N's and oriental 2sa/2sc--2sb/2sd are not anymore as I've known them for years.
I'm an old man... and shifted from perspective completely.
(*) Hence 'garden': protect the abundency
I would posit a reason that many bjts, which were a mainstay for decades, have gone by the wayside. I think in a similar way that tubes were gradually replaced in the mainstream by BJTs. They're obsolete. Stay with me here.
For one, consumer electronics has moved on from discrete components. For the small stuff (and even power amplifiers now) everything is done by an IC or, better, a microprocessor.
Second, for power applications, BJTs have been all but replaced by better performing FET or IGBT devices. So there is little demand for power BJTs any more.
I'm not an industry expert so it's just my armchair observation. Read it as you will.
It's possible that if things get too bad, and stocks of usable BJTs fade away, a cottage industry will start up to pick up the pieces. But I don't think we are quite there yet.
For one, consumer electronics has moved on from discrete components. For the small stuff (and even power amplifiers now) everything is done by an IC or, better, a microprocessor.
Second, for power applications, BJTs have been all but replaced by better performing FET or IGBT devices. So there is little demand for power BJTs any more.
I'm not an industry expert so it's just my armchair observation. Read it as you will.
It's possible that if things get too bad, and stocks of usable BJTs fade away, a cottage industry will start up to pick up the pieces. But I don't think we are quite there yet.
Great analysis and conclusion.
I like this cottage, but it is like a worn photo from a washed ashore bottle from the past. We need this shift of perspective.
So, now it's up to the next generation. I'll be here to support thou all in my manners proper.
Cheerio,