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Old 4th August 2008, 12:40 PM   #1581
Shinja is offline Shinja  Japan
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Default 2SJ74 and J108 will be discontinued?

I had heard the infomation on a Japanese blog that 2SJ74 will be discontinued .
It means ,J108 ,almost same with J74,will be also discontinued .

Then,I saw the website of Toshiba-semiconductor and serch J74 and J108.
But any results was not found...

They may be a lot of stocks over the world ,
but you should buy them before sold out.

While ,what will be the replacement of them ?J103 and K246?or J104 and K364?
We have only few coices left.
It will be disscuss on Japanese web too.
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Old 4th August 2008, 03:07 PM   #1582
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I don't get it why is this semiconductor company discontinuing this part, which is pretty much still in demand? They could still make a lot of money out it, specially with the DIY'ers around the world. Do you think they will come up with a better JFET?
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Old 4th August 2008, 10:12 PM   #1583
mlloyd1 is offline mlloyd1  United States
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unfortunately, i think the big picture that we don't see is Toshiba really doesn't make much profit on those jfets, especially considering the numbers of other devices like memories, mosfets (for switching supplies), microcontrollers, etc. their bean counters prefer to sell. discrete semiconductor sales to high performance audio manufacturers is insignificantly buried under the noise

too bad some of the other premium jfet manufacturers haven't got high performance p channel devices.

allegedly, they're working on it. but the word is don't hold your breath ...
not to mention all our screaming at the high prices if/when they do.



mlloyd1
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Old 5th August 2008, 10:31 AM   #1584
dhole is offline dhole  United Kingdom
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Default Jfet Matching

I have my boards nearly populated and eveything wlse ready to go. As far as I can tell matching the P to N mosfets isnt so critical. Is the JFet matching critical ? I am unsure of how to test them for idss ( I have searched alot for a diagram of a circuit ) Im just chuffed to bits that my first homemade pcb worked and Im on a roll !

dave
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Old 5th August 2008, 11:44 AM   #1585
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JFets should be matched.

Look at page 11: http://www.passdiy.com/pdf/diyopamp.pdf
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Old 5th August 2008, 12:04 PM   #1586
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Erno Borbely also has a pair of articles archived on his site -- which includes a JFET tester circuit.

http://www.borbelyaudio.com/adobe/ae599bor.pdf

and

http://www.borbelyaudio.com/adobe/ae699bor.pdf

Somewhere in this mess of an office I have a USB Based JFET analyzer based on the Measurement Computing data acquisition card -- it's written in VB.net
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Old 5th August 2008, 01:40 PM   #1587
pencoat is offline pencoat  Canada
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Quote:
Originally posted by Nelson Pass
Perhaps you would like to give each channel its own LC leg.


Thanks Nelson for the good advice
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Old 5th August 2008, 11:04 PM   #1588
skidave is offline skidave  United States
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Sorry I'm a little late on the F5 project...due to a baby and an ugly thing called WORK.

Was the article in AudioExpress? I read my issues top to bottom??? Also, are circuit boards being made for this project?

Dave
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Old 6th August 2008, 02:36 AM   #1589
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Quote:
Originally posted by yggdrasil
JFets should be matched.

Look at page 11: http://www.passdiy.com/pdf/diyopamp.pdf
Matching P to N channel devices is not practical, but using the same
selection codes (BL, GR, V) is desirable.

I don't match P to N devices, just like types.
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Old 6th August 2008, 03:07 AM   #1590
paulb is offline paulb  Canada
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Quote:
Originally posted by skidave
Was the article in AudioExpress? I read my issues top to bottom??? Also, are circuit boards being made for this project?

Dave
Yes, and yes.
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