Bipolar Caps for decoupling?

jtsaudio · 26th March 2009, 05:06 PM

Can you use non-polar electrolytics as local (power supply) decoupling capacitors?

I've searched and found only threads about polar electrolytic caps as coupling caps...

My power amp's input diff-amp circuit specifies a 100uf/50v polar electrolytic, but all I have are some (high quality)220uf/50v non-polar electrolytics on hand.

Will these work ok?

If no, then why not ?

-Joe

AndrewT · 26th March 2009, 05:17 PM

The nonpolar will work, they are capacitors.
You have paid a premium for the nonpolar capacity, that does not get used in this instance. This results in poor value.

Polar capacitors designed specifically for decoupling duty also sell at a premium, but in this case the extra performance is of some benefit. Maybe better value?

jtsaudio · 26th March 2009, 05:28 PM

Quote:

Polar capacitors designed specifically for decoupling duty also sell at a premium, but in this case the extra performance is of some benefit. Maybe better value?

Thanks Andrew, but what benefit, if any?

Does this mean that (in my case) Nichicon Muse polar caps will outperform the more expensive Muse NP types? Enough to warrant replacing these NP types?

While I'd spend a bit more for better results, are the NP's in any way inferior?

Anyone??

-Joe

clm811 · 26th March 2009, 06:05 PM

Hi Joe!

I have done this before and they worked fine; however, I don't know if they are any better/worse than polars in this application.

There's quite a bit written about using Black Gate N-series (nonpolar) as decoupling caps, so I don't see where there should be any problems using the Nichicons.

Maybe Andrew can elaborate on what benefits a high-grade polar cap would give (maybe related to ESR)?

jtsaudio · 27th March 2009, 06:09 AM

Thanks Chas

It's not that I can't afford to buy good polar electrolytics, just that I had these lying around and I figure that if they're good enough quality for signal path, that they might be great in a power supply.

-Joe

MCampbell · 28th March 2009, 06:04 PM

Continuing on the same tangent, I recently came across a metallised polyster film capacitor series that is in standard production which goes as high as 470uF @ 63V. They're certainly wouldn't be cheap, and they're obviously quite chunky, but I guess they would definitely represent and interesting alternative to electrolytics....
And you'd only need 21 of them in parallel to form a 10,000uF @ 63V PSU cap !!!!

alan monro · 29th March 2009, 08:58 AM

Goday Jts audio. Absolutely no advantage using bipolar caps in power supply . Why do it?? Can you give us a reason , Kind regards , Alan .

jtsaudio · 29th March 2009, 11:35 AM

Quote:

Why do it? Can you give us a reason?

Please re-read post #5.

-Joe

26th March 2009, 05:06 PM	#1
jtsaudio diyAudio Member Join Date: Dec 2007	Bipolar Caps for decoupling? Can you use non-polar electrolytics as local (power supply) decoupling capacitors? I've searched and found only threads about polar electrolytic caps as coupling caps... My power amp's input diff-amp circuit specifies a 100uf/50v polar electrolytic, but all I have are some (high quality)220uf/50v non-polar electrolytics on hand. Will these work ok? If no, then why not ? -Joe

26th March 2009, 05:17 PM	#2
AndrewT diyAudio Member Join Date: Jul 2004 Location: Scottish Borders	The nonpolar will work, they are capacitors. You have paid a premium for the nonpolar capacity, that does not get used in this instance. This results in poor value. Polar capacitors designed specifically for decoupling duty also sell at a premium, but in this case the extra performance is of some benefit. Maybe better value? __________________ regards Andrew T.

29th March 2009, 08:58 AM	#7
alan monro diyAudio Member Join Date: Apr 2008	Caps Goday Jts audio. Absolutely no advantage using bipolar caps in power supply . Why do it?? Can you give us a reason , Kind regards , Alan .

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26th March 2009, 06:05 PM	#4
clm811 diyAudio Member Join Date: May 2002 Location: Northern California	Hi Joe! I have done this before and they worked fine; however, I don't know if they are any better/worse than polars in this application. There's quite a bit written about using Black Gate N-series (nonpolar) as decoupling caps, so I don't see where there should be any problems using the Nichicons. Maybe Andrew can elaborate on what benefits a high-grade polar cap would give (maybe related to ESR)?

27th March 2009, 06:09 AM	#5
jtsaudio diyAudio Member Join Date: Dec 2007	Thanks Chas It's not that I can't afford to buy good polar electrolytics, just that I had these lying around and I figure that if they're good enough quality for signal path, that they might be great in a power supply. -Joe

28th March 2009, 06:04 PM	#6
MCampbell diyAudio Member Join Date: Nov 2008	Continuing on the same tangent, I recently came across a metallised polyster film capacitor series that is in standard production which goes as high as 470uF @ 63V. They're certainly wouldn't be cheap, and they're obviously quite chunky, but I guess they would definitely represent and interesting alternative to electrolytics.... And you'd only need 21 of them in parallel to form a 10,000uF @ 63V PSU cap !!!!

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