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Old 15th September 2012, 11:34 PM   #1191
gootee is offline gootee  United States
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"Parallel decoupling capacitances", taken to one of its logical conclusions:

(Of course, this would be done for each power rail. Only one is depicted.)
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Old 15th September 2012, 11:42 PM   #1192
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Thanks Gootee, will tickle your bone tomorrow got a football game to watch
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Old 15th September 2012, 11:47 PM   #1193
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Originally Posted by OnAudio View Post
Thanks Gootee, will tickle your bone tomorrow got a football game to watch
Enjoy! (That reminds me... there's still some beer in my refrigerator.)

But how do you have time to watch football?
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Old 15th September 2012, 11:52 PM   #1194
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Quote:
Originally Posted by gootee View Post
"Parallel decoupling capacitances", taken to one of its logical conclusions:

(Of course, this would be done for each power rail. Only one is depicted.)
Great Tom, thank you!

(taken to extreme the idea, I would go for one only reservoir capacitor, i.e. no Cres-L-Cres. Wouldn't you?)

Stefano

Last edited by seppstefano; 15th September 2012 at 11:54 PM.
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Old 16th September 2012, 12:00 AM   #1195
gootee is offline gootee  United States
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Originally Posted by seppstefano View Post
Great Tom,
but taken to extreme the idea, I would go for one only reservoir capacitor, i.e. no Cres-L-Cres.

Wouldn't you?

Stefano
Stefano,

Could you please explain further?

I can't quite picture what you mean. I think that what I showed would give the lowest impedance, as seen by the load, since the Cs would tend to multiply by N and the L and R of the capacitors AND of the CONDUCTORS would tend to be divided by N, where N is the number of duplicated power/gnd rail pairs.

Or did you mean to use only one reservoir cap per pair? Maybe one before they divide and one per pair would be better. Or add one before they divide, just after the rectifiers, so the charging pulse currents could be kept out of the rest of the circuit.

Tom
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Old 16th September 2012, 12:14 AM   #1196
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Originally Posted by gootee View Post
Stefano,

Could you please explain further?

Or did you mean to use only one reservoir cap per pair? Maybe one before they divide and one per pair would be better. Or add one before they divide, just after the rectifiers, so the charging pulse currents could be kept out of the rest of the circuit.

Tom
I was just simply imaging the first option. To remove the inductance between reservoir caps. The resonance between the single reservoir cap and the local cap would be damped by the resistive components of the wire in between (so a sort of Cres-Lwire-Rwire-Clocal).

Should I need more capacitance, voilą just add another whole line.

But it's late in the night here, and I've got some red wine.... hic!
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Old 16th September 2012, 12:20 AM   #1197
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Quote:
Originally Posted by seppstefano View Post
I was just simply imaging the first option. To remove the inductance between reservoir caps. The resonance between the single reservoir cap and the local cap would be damped by the resistive components of the wire in between (so a sort of Cres-Lwire-Rwire-Clocal).

Should I need more capacitance, voilą just add another whole line.

But it's late in the night here, and I've got some red wine.... hic!
Now I think I understand. But those are assumed to be electrolytic caps and their ESR should be enough damping that we don't have to worry about any resonant LC "tank" circuits being formed. (That WOULD be a danger, if we put a film cap near the electrolytics.)

Your point about just adding another whole parallel pair, if more capacitance is needed, is well taken.

(Yeah, I think I have a nice Cabernet or Merlot here, somewhere. Sounds like a good idea.)

Last edited by gootee; 16th September 2012 at 12:22 AM.
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Old 16th September 2012, 12:26 AM   #1198
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...hope that will also "tastes" like a good idea

Thank you, I simply didn't take in enough consideration the ESR of reservoir caps... (I wrote it was late, etc etc)
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Old 16th September 2012, 12:31 AM   #1199
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Originally Posted by Nico Ras View Post
Tom, those graphs reveal a lot of information provided that the observer realises that the output signal (driving the load is fixed) and only the error benefits can be had. Now at what point does the error represent noting more worth pursuing.

From the data you present I would select 6000uF as being overly suitable for all three applications.and will split them into 6 x 1000 uF or even 12 x 500uF, if real-estate is not at premium I would go for 60 x 100uF.
Nico,

Yes, the question is, "How low is low-enough, for the distortion?".

Maybe I will play some music through the simulated amplifier and listen to the result, for different capacitances, and listen for any difference.

I can make the WAV files from the output, for several different capacitance values, and then burn a CD and take it to my good audio system (i.e. not use the computer's sound card to play them).

If the results are interesting, I could even post the WAV files on line.

(I hope I still have that WaveEdit demo software. I definitely can't wait for it to process an entire song.)

Tom
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Old 16th September 2012, 12:46 AM   #1200
gootee is offline gootee  United States
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Quote:
Originally Posted by seppstefano View Post
...hope that will also "tastes" like a good idea

Thank you, I simply didn't take in enough consideration the ESR of reservoir caps... (I wrote it was late, etc etc)
Hey, at least you're thinking about the possible resonances! That doesn't even occur to most people. Good work.
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