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Old 29th August 2012, 05:27 AM   #471
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No, Hfe isn't one of the fundamentals of transistor operation, there's significant process variation.
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Old 29th August 2012, 05:34 AM   #472
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Quote:
Originally Posted by EUVL View Post
1/22mS = 46 ohm.

And 22mS comes from first page of data sheet :
2SK170?Junction FETs (Single/Dual)?TOSHIBA Semiconductor & Storage Products Company

Mr. Wavebourn is assuming the NPN has zero emitter resistance, which is of course not 100% true.
It depends on the bias.
No, Mr Wavebourn does not assume that emitter resistance is zero, as well as that beta is infinite. But I assume that 47K would be close enough.
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Old 29th August 2012, 05:45 AM   #473
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47 ohm I guess, not quite so close to 47k.
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Old 29th August 2012, 05:46 AM   #474
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Originally Posted by EUVL View Post
47 ohm I guess, not quite so close to 47k.
Yes, sorry for the typo.
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Old 29th August 2012, 06:01 AM   #475
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Originally Posted by abraxalito View Post
No, Hfe isn't one of the fundamentals of transistor operation, there's significant process variation.
Pardon my (evedently) **** poor education on the subject.
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Old 29th August 2012, 06:03 AM   #476
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Default Spec goal in design -

Here is were some spec numbers came from as goal - see line #279 of Marsh headphone amp forum.
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Old 29th August 2012, 06:03 AM   #477
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Originally Posted by Wavebourn View Post
No, Mr Wavebourn does not assume that emitter resistance is zero, as well as that beta is infinite. But I assume that 47K would be close enough.

47 Ohm or 47 kOhm ?
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Old 29th August 2012, 06:05 AM   #478
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Originally Posted by hitsware View Post
Pardon my (evedently) **** poor education on the subject.
But you have been educated on this subject - you yourself said that 'the enlightened know transistors are voltage controlled' That Hfe isn't well defined is a corollary of this I believe.
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Old 29th August 2012, 06:59 AM   #479
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Originally Posted by scott wurcer View Post
At 20k the base current re-capture lowers the open-loop distortion by 30dB.
Cute. Brings memories of Malcolm Hawksford.
So far the only real novelty in the barrage of 'me-too' circuitry

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Last edited by jan.didden; 29th August 2012 at 07:01 AM.
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Old 29th August 2012, 07:36 AM   #480
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Cute. Brings memories of Malcolm Hawksford.
So far the only real novelty in the barrage of 'me-too' circuitry

jan
This is a critical tool, and as I and Jung have shown elsewhere, dates back well before Hawksford to Boxall and Aldridge. Walt is working on the all-JFET history so I won't go into that here.
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