Re: JU570-2 caps and fix

From: HÁRSFALVI Levente <>
Date: Wed, 22 Jul 2015 19:54:09 +0200
Message-ID: <>
On 2015-07-22 17:46, William Levak wrote:
> On Mon, 20 Jul 2015, H�~ARSFALVI Levente wrote:
>> Hmmm... connecting two unipolar caps antiparallel appears to me like
>> making it sure that either of the caps _will_ be charged up with wrong
>> polarity as soon as a voltage is applied.
> Except that the one will not charge because it is the wrong polarity,
> and the other will. ...

I was curious and looked up some information. On page 6 of this guide, one can find the 
equivalent circuit of a regular alu electrolytic capacitor, amongst 
other interesting things. In short, 1.) such caps can just be considered 
bipolar capacitors as long as reverse voltage bias is kept below 
1...1.5V, since there's no change in their parameters under these 
circumstances, and 2.) they'll survive short high reverse voltage bursts 
(although with high leakage current).

So, the above antiparallel arrangement should work as long as those 
limits are kept (ie. operating voltage across the cap terminals is less 
than 1..1.5V). ...Though, one could then ask what the fuss was about if 
a single cap should just work under those conditions equally well.

(I hope there's no disagreement whether a unipolar cap, with high i.e. > 
1.5V continuous reverse voltage bias, will go up in a burst sooner or 

> Nothing would go through that arrangement, as one or the other capacitor
> would block the signal.  It's like connecting two diodes is series back
> to back.

To my best knowledge, that arrangement is regularly used to substitute 
bipolar electrolytic caps.

Best regards,


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