questions on Capacitor rating?

nina · 2nd April 2006, 05:47 PM

Hi,

Just wonder if there are any recommendation on how to select voltage rating for capcitor, esp. filter cap? How many percent of extra volatge rating required?

Is that safe to use 56Vdc (from 40-0-40 tranformer) with a cap 63V?

Thanks,

anatech · 2nd April 2006, 05:49 PM

Hi nina,
Yes, you are perfectly safe.

-Chris

pinkmouse · 2nd April 2006, 06:08 PM

Well, the caps may be safe, but the chip amp would likely blow up, 56 V rails are way over spec for all the ones I can think of.

AndrewT · 2nd April 2006, 06:16 PM

Hi,
40Vac will take the 63Vdc cap right to the limit if the regulation of the transformer is about 5%.
If the transformer regulation is more than 5% then you should use 75Vdc or 80Vdc caps.

But Pink is right. You probably need a 25Vac or 30Vac transformer.

anatech · 2nd April 2006, 06:24 PM

I guess the question now is, what chip amp? What is the N.L. DC voltage? Some STK chips will run this high.

Andrew is correct in that an unloaded transformer will output a much higher voltage than it's rated at. Your AC mains could very well take this over the cap rating.

It is okay to use a 63V cap when the measured DC is around 56V. I have seen worse in mass market units.

-Chris

poobah · 2nd April 2006, 06:29 PM

Did Nina say chip amp? Who said chip amp?

Caps these days are generally given 2 ratings: "WORKING VOLTAGE" & SURGE.

Caps perform at their peak when run as close to, but NOT over their WVDC (Working Volts DC) rating.

So... 40 times 1.414 times 110% = 63 Volts... PERFECT!!!!!!!!!!

Pull up to the second window...

pinkmouse · 2nd April 2006, 07:11 PM

Quote:

Originally posted by poobah
Did Nina say chip amp? Who said chip amp?

We are in the chip amp forum!

poobah · 2nd April 2006, 07:15 PM

uh... uh... uh...

anatech · 2nd April 2006, 07:15 PM

Yup,
Poobah, some times it's all about location, location, location.

-Chris

poobah · 2nd April 2006, 07:17 PM

Jeeze guys... I'm working with 2 brains cells here... one wants a drink and the other has a hangover.......

2nd April 2006, 05:47 PM	#1
nina diyAudio Member Join Date: Apr 2005 Location: Earth	questions on Capacitor rating? Hi, Just wonder if there are any recommendation on how to select voltage rating for capcitor, esp. filter cap? How many percent of extra volatge rating required? Is that safe to use 56Vdc (from 40-0-40 tranformer) with a cap 63V? Thanks,

2nd April 2006, 06:08 PM	#3
pinkmouse diyAudio Moderator Join Date: Apr 2002 Location: Chatham, England	Well, the caps may be safe, but the chip amp would likely blow up, 56 V rails are way over spec for all the ones I can think of. __________________ Al The miracle is not to fly in the air, or to walk on the water; but to walk on the earth. Chinese Proverb

2nd April 2006, 06:16 PM	#4
AndrewT diyAudio Member Join Date: Jul 2004 Location: Scottish Borders	Hi, 40Vac will take the 63Vdc cap right to the limit if the regulation of the transformer is about 5%. If the transformer regulation is more than 5% then you should use 75Vdc or 80Vdc caps. But Pink is right. You probably need a 25Vac or 30Vac transformer. __________________ regards Andrew T.

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2nd April 2006, 05:49 PM	#2
anatech diyAudio Moderator Join Date: Jun 2004 Location: Georgetown, On	Hi nina, Yes, you are perfectly safe. -Chris

2nd April 2006, 06:24 PM	#5
anatech diyAudio Moderator Join Date: Jun 2004 Location: Georgetown, On	I guess the question now is, what chip amp? What is the N.L. DC voltage? Some STK chips will run this high. Andrew is correct in that an unloaded transformer will output a much higher voltage than it's rated at. Your AC mains could very well take this over the cap rating. It is okay to use a 63V cap when the measured DC is around 56V. I have seen worse in mass market units. -Chris

2nd April 2006, 06:29 PM	#6
poobah diyAudio Member Join Date: Nov 2005	Did Nina say chip amp? Who said chip amp? Caps these days are generally given 2 ratings: "WORKING VOLTAGE" & SURGE. Caps perform at their peak when run as close to, but NOT over their WVDC (Working Volts DC) rating. So... 40 times 1.414 times 110% = 63 Volts... PERFECT!!!!!!!!!! Pull up to the second window...

2nd April 2006, 07:15 PM	#8
poobah diyAudio Member Join Date: Nov 2005	uh... uh... uh...

2nd April 2006, 07:17 PM	#10
poobah diyAudio Member Join Date: Nov 2005	Jeeze guys... I'm working with 2 brains cells here... one wants a drink and the other has a hangover.......

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