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Old 10th April 2003, 07:31 PM   #11
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Default Re: When the theorical meet....

Quote:

PS: I have seen some japonese constructors even with +-45 volts rails use 25 Volts rated elect. capacitors in series with the lower arm resistor of the feedback voltage divider...maybe they are pushing their luck to far!!
No, I guess it is reasonable design practice. Under any normal
operation circumstances it is sufficient, and if something goes
terribly wrong, you will most likely end up with more important
components being damaged, perhaps even your speakers.
However, I guess my point was that when you build an amp
yourself and it is not yet tested, something may be wrong so
you actually get rail voltage over the capacitor. Most likely the
amp is not sealed within a box when testing it, so an exploding
electrolytic can be a nasty epxerience. That said, exploding
semiconductors can also be nasty and dangerous -- I have
experience of that. Wear protective glasses when working
with untested circuits.
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Old 10th April 2003, 07:35 PM   #12
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It seems we got so involved in voltage ratings that we forgot
Christians other question, whether it is OK to use a 2.2uF
capacitor instead. The answer is no, even 10uF is lowish, since
it gives a low frequency cutoff at 16Hz. I would recommend
at least 22 or 33uF.
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Old 10th April 2003, 07:48 PM   #13
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Default when the theorical meet...reprise...

Quote:
so an exploding
Quote:
electrolytic can be a nasty epxerience
Of corse!!!

But try this...if you have a old 25 volt capacitor...connect it reverse biased to a your lab power supply set at 30 Volts DC via a 21 k resistor....you will see that the cap will not explode and doesn't even become warm...
Quote:
exploding
Quote:
semiconductors can also be nasty and dangerous
Quote:
I have
Quote:
experience of that
Me to!!...and the worst of all is the smell!!!

Cheers
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Old 10th April 2003, 08:04 PM   #14
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Default Re: when the theorical meet...reprise...

Quote:
Originally posted by Tube_Dude

But try this...if you have a old 25 volt capacitor...connect it reverse biased to a your lab power supply set at 30 Volts DC via a 21 k resistor....you will see that the cap will not explode and doesn't even become warm...
Probably the leakage current will be so large that it never gets
charged to sufficiently high voltage. I don't think one should
count on that, however.
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Old 10th April 2003, 09:18 PM   #15
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Default Re: What is this capacitor for?

Quote:
Originally posted by Christian
I'm about to build a gainclone, and I don't have that cap ( encircled in the schematic), so could I use the caps in the picture, 100V, 2.2 microF?

I do have 10 microF caps, but their only 25 Volts rated, so they might blow up if I apply +- 30 V to the circuit right?

/Christian
Hi Christian,
I would use 4 or 5 pieces of the orange MKT 2.2F in parallel or better still 10F polypropylene.


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Old 11th April 2003, 12:13 AM   #16
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Default WOW.

Hi,

Just finished reading this thread for the fun of it.

Quote:
I would use 4 or 5 pieces of the orange MKT 2.2F in parallel or better still 10F polypropylene.
At long last...guess it pays to be Dutch and have your feet firmly on the ground.

No offense to anyone,
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Old 14th April 2003, 04:02 PM   #17
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Ok,

so I went with the 25 Volt Caps anyway. But there's only one problem with these, they are polarized

I understand that I'm taking a slightly larger risk by using polarized caps, but will it affect the sound, and how? I've tested this configuration and it seems to work juste fine.

Here is what the modules look like, I'm building a 5 channel amp with these.

/Chris
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