Hi. Thimios,
The circuit is right but the part numbers don't match.
R24 on the plan is R25 on the schematic
The trimmer is R24
The R27 to the left of the trimmer is R23
Also check the foil. There is a link missing on one of the small transistors.
Have you determined which is the Best CFA circuit yet or is that still evolving? But if there are going to be changes again and again.....
I will never get to building anything. Give me the best CFA schematic spec-wise... IPS and OPS. The whole thing.... best of everything.... so far. But only CFA.THx-RNMarsh
"The R27 to the left of the trimmer is R23"
No Terry,isn't R23.It is R28 ,from the collector of Q9 to GND.(according to schematic).
The other resistor to the right of the trimmer is R29 from collector of Q10 to the GND.
The resistor R24(PCB artwork) is the R25 on the schematic.
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In the response curve ?
If you want my opinion, never allow this. Never !
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Have you determined which is the Best CFA circuit yet or is that still evolving? But if there are going to be changes again and again.....
THx-RNMarsh
That is the whole reason for the modular setup. Have your ready output stage
"a waiting" for the next "evolution". OPS is perfected !
The one still4given is presently building (kypton-c) is the end result of
6 months of "playing" with CFA topologies.
While I do appreciate you getting me interested in the CFA's , my VFA experience (mirrors , ccs's , better VAS's) allows me to output a CFA
with 5ppm THD20 , 100db psrr , and no offset.
As no one has complained about the 20ppm "cfa-x" , I assume it is a
pleasing project. In fact , it was sold out (I did not even get a sample 🙁 ).
Going in the opposite direction - knowing what attributes make the
CFA's desirable has allowed me to make the kypton-V, A vfa with
250v/us slew that has a similar bode response to a cfa.
The last one (IPS) I will do is a CFA/VFA IC hybrid "eyesee". The
current feedback node is the output of a op-amp ! 2 feedback loops ...
one VFA (the op-amps local FB) and the op-amp- I/V convertor (discrete
current FB).
OS
Aah, so 'EyeSee' is still in the queue. I am eager to see what you do with that one.
Just wait till you meet "Spartacus S-500", my pet VFA with CFA slewing, with HEC included NFB. 1KW/8R 20K bridged sub-ppm =)
Sorry, I wrote that from memory. My bad. I got it right when I installed them.
I have a pair for you. PM me.
Again, just my opinion, if you drive a formula one (CFA ?), fight for speed.. And don't worry too much about reasonable HD ;
if you drive a Rolls Royce (VFA ?), fight for comfort ;-)
The character of both is in listening.
Mark Alexander like ? (Current mirrors on the power pins of the OPA ?)
http://scopeboy.com/original.gif
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I fixed them all ... The schema HAS to be right (simulation would not work).
The art work was in error (below -fixed) Q12 - R21 had a missing bridge -
was that what was seen ??
Even as this IPS gets stellar performance "as is" ....
You can increase the current in the feedback network (R14/15 -R16/17
39R - 1K) plus increase the current mirror I (R7 +R9 - 8.2k ... 1.4ma).
for 1-2ppm @ 20k. (below 2).
Kypton C is very "friendly" to "tweaks" !!
OS
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Alrighty then, a bit of Spartacus for you then 🙂 Who needs bulky class A when you can have a powerful AB with a distortion profile lower than about what any class A pushes out!?
kgrlee: note C28, the gateway to unconditional stability 🙂
Edit: It may disappoint some, but yes, Spartacus is a VFA.
kgrlee: note C28, the gateway to unconditional stability 🙂
Edit: It may disappoint some, but yes, Spartacus is a VFA.
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