# 4+4.5+5uf 250 VAC Fan Capacitor CBB61



## keeperofthegood (Apr 30, 2008)

4+4.5+5uf 250 VAC Fan Capacitor CBB61 on eBay.ca (item 120612730056 end time 20-Jan-11 11:15:13 EST)












Some of the old designs use very low capacitance filter caps. I was just wondering, is there any reason these fan caps would not do in such a power supply? 1 to 8 uf values would be fine, just wondering about the cap itself.


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## jb welder (Sep 14, 2010)

That would be an AC voltage rating so you would need to know what kind of DC they can handle.
As far as using bi-polar caps. (as opposed to electrolytics) as filter caps, maybe others here can comment on this as it is unknown territory for me. 
In crossover applications we see both bi-polar electrolytic and non-electrolytics used so I would think something like this would work for crossover applications, but as far as filter caps go I know not.
Would like to hear from Wild Bill on this one!


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## WCGill (Mar 27, 2009)

If this is a motor run capacitor, it will work in a power supply. If it is a motor start capacitor, it's not suitable for continuous duty. DC voltage rating would be 1.4 times AC rating, conservative value, possibly double.


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## keeperofthegood (Apr 30, 2008)

CBB61 (MKP) Metallized Polypropylene AC motor run Capacitor-Box type

I think all the cbb61's are motor run caps. I find they are mostly listed that way or as a 'start/run dual application suitable' or words to that effect.

What I do not understand on that data listing is the line:

[FONT=Arial, Helvetica, sans-serif]Withstand Voltage(VDC)[/FONT] [FONT=Arial, Helvetica, sans-serif]2.0Ur (2S), 1.75Ur (5S)[/FONT]

What is Ur?


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## WCGill (Mar 27, 2009)

I'm not conversant with these specs, it would be best to ask the supplier, although if this is from ebay, there could be some difficulty.


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## keeperofthegood (Apr 30, 2008)

True, and from China if I bought that route. Though I think I have encountered them at a decent price locally, it tickles the greying matter a bunch. I am going to keep my eyes open next time I am at some of the various surplus shops  Though, as to who's specs to chose, I think they should all be the same as they are an ISO spec no?


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## jb welder (Sep 14, 2010)

From what I can decipher, it can withstand DC at 2 times rated AC for 2 seconds?
Extrapolated from this:
Operating Conditions for RF Capacitors | Capacitor Tutorials | Operating Conditions for RF Power Capacitors
Still doesn't suggest what actual working DC volts would be.


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