Different values of C7 (CE) in Alephs - diyAudio
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Old 4th February 2003, 02:28 PM   #1
Josep is offline Josep  Europe
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Join Date: Jan 2002
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Smile Different values of C7 (CE) in Alephs

Hello all

I am making an Aleph 30 with Kristijan PCBs for Aleph 5.
It is easy to adapt but my doubt is about C7.
The only difference in my A30 is that C7 is from the collector to emitter instead collector to base in original A30.
BrianGT ask to Mr. Pass about similar problem and he say :
"The value of the npn compensation cap pretty much depends on the placment. .001 for CB or .01 for CE."
I see different schematics with 0.047 or 0.01 for collector to emitter placement. What it is the correct value in this case?
Thank you


Note : Sorry for my bad English.
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Old 4th February 2003, 02:39 PM   #2
uli is offline uli  Austria
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Join Date: Dec 2002
Location: Vienna, Austria
Default try and error

this cap is either nfb (CB) or output to gnd (CE).
It forms a lo pass with R18 in the CE config.
in CB it forms a fb loop thus "slowing down" the npn
to avoid oszillation.
I would put either .001 in CB or .047 in CE.
Try it!

'Jazz is not dead, it just smells funny' F.Zappa
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Old 4th February 2003, 02:39 PM   #3
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I would trust Mr. Pass!
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Old 4th February 2003, 05:28 PM   #4
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Lots of times it works fine without a cap, but not
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