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Old 30th January 2012, 09:27 PM   #5011
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Sampler, i have to digest it but error feed forward is a great way to do it. I can make a better mirror too then in the Pardise but i decided on moderate output impedance because of DC offset issues.
What i would really like to see is your design in parallel symmetric ( if better or necessary ) with a balanced, differential input stage. J-Fet input or not. If we only use N-Channels this is not a component sourcing problem anyway. We can call that the Starless-Balanced and i would 100% support that design.
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Old 30th January 2012, 09:38 PM   #5012
MiiB is offline MiiB  Denmark
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and what does Q53.. do..???

I think i have some place where this could fit nicely....now some current feedback must be.. thought out...
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Old 30th January 2012, 09:50 PM   #5013
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I would say that the emitter of Q53 is the buffer output.
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Old 30th January 2012, 09:55 PM   #5014
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I will draw the schematic how i understand it.
Nevertheless i do not like to change the Paradise. This is the Paradise and that is something different.
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Old 30th January 2012, 10:04 PM   #5015
MiiB is offline MiiB  Denmark
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oh yes.. paradise is made with concept that is, this could have its place in other applications...
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Old 30th January 2012, 10:07 PM   #5016
RCruz is offline RCruz  Switzerland
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Quote:
Originally Posted by Joachim Gerhard View Post
My schematic says R47 = 10 Ohm R51 = 15 Ohm
so they are different
This resistors set bias in the output stage so there is 50% more voltage over the 15 Ohm resistor
That affects output DC offset, that is corrected by the servo anyway.
Say 2mA flow over the 10 Ohm so we have Ube plus 10 Ohm x 2mA = 0,65V plus 0,02V = 0,67 V. That develops also from base to output in the output so the output idles at 1,333mA. You can calculate the same in the other polarity with 15 Ohm. Ube can be different in NPN and PNP transistors though. That values look a bit off to me because the input stage would idle more then the output stage that may have a harder load to drive. 22 Ohm seems to be more correct.
So R47 = 10 and R51 = 22 ??
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Old 30th January 2012, 10:16 PM   #5017
MiiB is offline MiiB  Denmark
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22 ohm is the correct value...the size depends on the current injected by the mirrored current source. Target is that the output buffer has app 5 mA running.
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Old 30th January 2012, 10:25 PM   #5018
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So I keep R51 as 22r and reduce R47 until I get 5mA running in the buffer...
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Old 30th January 2012, 10:26 PM   #5019
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This is how i understand it.
I call it Starless Sampler Mirror Balanced.
SSMB.
Attached Files
File Type: pdf Starless Sampler Mirror 1.0 31.1.2012.TSC - TINA.pdf (8.6 KB, 95 views)
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Old 30th January 2012, 10:36 PM   #5020
RCruz is offline RCruz  Switzerland
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Hi Miib could you please explain why the difference in R19... Inittially was different, than I believed it was 15k as in the board, but this final schematic says 8.1k...
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