AC Electrolytic Capacitor Question

[backjourne]

Hello All,

I have a brief question regarding polar electrolytic capacitors in AC applications. My understanding is that the use of polar electrolytic capacitors is acceptable in AC circuits if two are placed in series but with opposite orientations. What is the effective capacitance of this arrangement?

My understanding is that these capacitors will conduct if a voltage >2V is imposed in the reverse polarity. Because of this, I think the effective capacitance is equal to that of a single capacitor (i.e., it’s not halved) while the ESR is doubled. I can’t measure this with my RCL meter because it does not have a great enough output voltage.

Thanks for any help.

 

[MacGyverS2000]

And where did you learn these nuggets of understanding?

Dan - Owner

http://www.Hi-TecDesigns.com

 

[Skogsgurra]

Don't do that!

You can have the back-to-back arrangement, but put a diode parallel to each capacitor so it doesn't get any reverse polarity. Reverse polarity erodes the Al2O3 insulating layer very quickly.
You will get zero-crossing distorsion. But that a price you have to pay if you select this sneak solution. Better buy real AC electrolytics - or us film capacitors.

Gunnar Englund

http://www.gke.org

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