Capacitor question

woody · 15th January 2002, 12:39 AM

If I were to build a power supply using a center taped transformer and a full wave bridge to supply + and - 30vdc
at 5a what would be the minimum ripple current rating needed
for the filter caps?

Thanks

bob12345678 aka Woody I had some trouble logging on!

Keithj · 15th January 2002, 03:23 AM

Here's some formulae...

The ripple current through a capacitor for a full wave rectifier system is:

Ir = Er * 2 * pi * f * C

Where Er is the ripple voltage, f is the frequency in hertz and C is the capacitance in farads.

Calculation of Er is more difficult. You need to know all the source resistances. Better to measure it. If you want the details, and you're able, find a copy of the Radiotron Designer's Handbook and read pages 1177 to 1182.

Good luck, Keith

kuma33 · 1st February 2013, 06:26 AM

Hi guys,
can anyone tell me what are the electrolytic's specifications what influencing the audio signal? Or just the dielectrics material, the foil material, etc.? I have some Hitano EHR series el.caps, but the documentations aren't containing informations about the usability in audio applications..

DF96 · 1st February 2013, 11:37 AM

Such a simple innocent question!

If there was a straightforward agreed answer then many threads on here could disappear and audio design would be more of an engineering discipline with less space for snake oil merchants and postmodern tree huggers.

DUG · 1st February 2013, 11:53 AM

Quote:

Originally Posted by kuma33

Hi guys,
can anyone tell me what are the electrolytic's specifications what influencing the audio signal? Or just the dielectrics material, the foil material, etc.? I have some Hitano EHR series el.caps, but the documentations aren't containing informations about the usability in audio applications..

The usual answer to general questions is:

It depends.

It depends on what you are using the cap for.

Electrolytics for power supply filtering...If lower ability then increased ripple or droop under load could cause increased 120Hz in output of amplifier or clipping at lower power levels. Transient or sudden power requirements may not be provided for with "lower grade" caps.(all other factors the same)

Electrolytics for signal coupling...here is where opinions vary.

IMHO, if the Electrolytics cap can maintain a low enough impedance throughout the frequency range of interest then there is no issue with its use for signal coupling.

Some data sheets will have information that will help you decide but it may not be blatantly labeled as "for use in xxxxx application"

Hope that helps.

kuma33 · 1st February 2013, 05:18 PM

Okay, i know the boof stuff, like "woodknob-resonance" or "amp chassis sound conduction", but the caps are different, because they are really in the signal path, like coupling or output elements..
But there are hundreds of cap types from low esr to long life, etc., and audio types too, like the silmics, with many, many parameters...

15th January 2002, 12:39 AM	#1
woody diyAudio Member Join Date: Jan 2002 Location: Tyrone Ga. U.S.A.	Capacitor question If I were to build a power supply using a center taped transformer and a full wave bridge to supply + and - 30vdc at 5a what would be the minimum ripple current rating needed for the filter caps? Thanks bob12345678 aka Woody I had some trouble logging on!

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15th January 2002, 03:23 AM	#2
Keithj diyAudio Member Join Date: May 2001 Location: New Zealand	Here's some formulae... The ripple current through a capacitor for a full wave rectifier system is: Ir = Er * 2 * pi * f * C Where Er is the ripple voltage, f is the frequency in hertz and C is the capacitance in farads. Calculation of Er is more difficult. You need to know all the source resistances. Better to measure it. If you want the details, and you're able, find a copy of the Radiotron Designer's Handbook and read pages 1177 to 1182. Good luck, Keith

1st February 2013, 06:26 AM	#3
kuma33 diyAudio Member Join Date: Jan 2013 Location: Szeged	Hi guys, can anyone tell me what are the electrolytic's specifications what influencing the audio signal? Or just the dielectrics material, the foil material, etc.? I have some Hitano EHR series el.caps, but the documentations aren't containing informations about the usability in audio applications..

1st February 2013, 11:37 AM	#4
DF96 diyAudio Member Join Date: May 2007	Such a simple innocent question! If there was a straightforward agreed answer then many threads on here could disappear and audio design would be more of an engineering discipline with less space for snake oil merchants and postmodern tree huggers.

1st February 2013, 05:18 PM	#6
kuma33 diyAudio Member Join Date: Jan 2013 Location: Szeged	Okay, i know the boof stuff, like "woodknob-resonance" or "amp chassis sound conduction", but the caps are different, because they are really in the signal path, like coupling or output elements.. But there are hundreds of cap types from low esr to long life, etc., and audio types too, like the silmics, with many, many parameters...