John Curl's Blowtorch preamplifier part II - Page 4847 - diyAudio
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Old 18th February 2014, 07:57 PM   #48461
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Originally Posted by Nelson Pass View Post
Can you spell Cascode?

Frederick Vinton Hunt Harvard 1939

Last edited by Triodethom; 18th February 2014 at 08:01 PM.
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Old 18th February 2014, 07:58 PM   #48462
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HTTP 301 This page has been moved

Ignore the text it links to the real package.

Was this the daddy of todays leadless SMD packages?
Yes that's the one. That package was a problem, sort of custom because our QA dept refused to deal with the vendors of cheap automotive SIP's. Believe it or not our cost was $0.95 at the 100k level, killed margins. I have played 8 Ohm bookshelf speakers with these (the sound of the thermal shutdown going off and on was something else).

BTW Walt J's 823/815 composite amp is a great line/headphone stage.
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Old 18th February 2014, 09:21 PM   #48463
RNMarsh is offline RNMarsh  United States
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Quote:
Originally Posted by scott wurcer View Post
The complements listed are usually at the same breakdown voltage and ft. The mobility of holes vs. electrons will push some parameters out of complement, it's the users choice which.
Some sources are "matched" compl only by their dc parameters - like Vbe and arent remotely alike for hfe or much of anything else. Some to92 compliments from NTE are like this. So, just noting that 'matched pair' can mean just about anything from mfr to mfr. Same breakdown and ft are hardly what we need for low distortion so finding matched pairs on the curve tracer is a good starting point.

THx-RNMarsh
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Old 18th February 2014, 10:06 PM   #48464
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RNMarsh,
This is exactly why I asked earlier if there are times when devices from different manufacturers could actually be the better match between devices. Matching the parameters that are important to you rather than something that really won't be the most effective for an audio application.
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Old 18th February 2014, 10:26 PM   #48465
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> Some to92 compliments from NTE are like this.

NTE is a supplier, not a manufacturer. I would
not use them as any kind of referance.

@ Kindhornman:
I still maintain my original stance on this question

http://www.edn.com/design/analog/440...ar-transistors

2n3904 - 2n3906
http://www.fairchildsemi.com/search/...&showAll=false

Last edited by hitsware; 18th February 2014 at 10:46 PM. Reason: addition
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Old 18th February 2014, 10:52 PM   #48466
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Originally Posted by hitsware View Post
>
@ Kindhornman:
I still maintain my original stance on this question
Yes, beta at the same Vce anymore is probably a waste of time.
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Old 18th February 2014, 11:01 PM   #48467
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Hitsware,
Okay, but Scott's earlier comment made it sound like the matching even what is being done is not really much of a match except at a very narrow range of value. Doesn't sound like any true complementary devices between NPN and PNP really exist even from the same manufacturer due to the process and plain old physics.
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Old 18th February 2014, 11:07 PM   #48468
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> Doesn't sound like any true complementary devices between
> NPN and PNP really exist even from the same manufacturer

OK , But I say the closest to being 'true' complementary pairs
are those designed as such. There may be some flukes that
indicate otherwise, but very few .
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Old 18th February 2014, 11:23 PM   #48469
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Quote:
Originally Posted by hitsware View Post
> Doesn't sound like any true complementary devices between
> NPN and PNP really exist even from the same manufacturer

OK , But I say the closest to being 'true' complementary pairs
are those designed as such. There may be some flukes that
indicate otherwise, but very few .
Same story on 2N3906/3904 hoe's very different.

BTW I don't get the big deal, designs should not need obsessive matching.
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Last edited by scott wurcer; 18th February 2014 at 11:26 PM.
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Old 18th February 2014, 11:30 PM   #48470
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> BTW I don't get the big deal, designs should not need obsessive matching.

To a certain degree, but that's like saying your transformers centertap
shouldn't need to be that close to the center
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