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Parts Where to get, and how to make the best bits. PCB's, caps, transformers, etc.

Equiv. Parts: 2SD669, 2SB649
Equiv. Parts: 2SD669, 2SB649
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Old 11th September 2019, 01:05 PM   #71
MarsBravo is offline MarsBravo  Netherlands
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Quote:
Originally Posted by merly View Post
Because I think you should make that clear.

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.
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Old 11th September 2019, 03:38 PM   #72
merly is offline merly  United Kingdom
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Originally Posted by MarsBravo View Post
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.

You have been very helpful thank you.
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Old 11th September 2019, 04:47 PM   #73
MarsBravo is offline MarsBravo  Netherlands
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You're welcome. If you're stuck next time just drop me a pm and I shall see what I can do.
It is not strange that one feels hindered where support is expected when trying to master a trade or even a usefull live.
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Old 11th September 2019, 07:00 PM   #74
ubergeeknz is offline ubergeeknz  New Zealand
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Originally Posted by merly View Post
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.
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.
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Old 11th September 2019, 09:37 PM   #75
MarsBravo is offline MarsBravo  Netherlands
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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
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Old 11th September 2019, 09:52 PM   #76
ubergeeknz is offline ubergeeknz  New Zealand
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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.
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Old 11th September 2019, 10:11 PM   #77
MarsBravo is offline MarsBravo  Netherlands
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Originally Posted by ubergeeknz View Post
...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,
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Old 12th September 2019, 08:21 PM   #78
Mark Tillotson is offline Mark Tillotson
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dB is a ratio, typically a power ratio, except when refering to sound pressure level.


Wikipedia will explain.
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