Replacing electrolytic with ceramic capacitors?

hcmtnbiker · Post by **hcmtnbiker** » Tue Jan 02, 2007 1:49 pm

I was wondering if there's any special stuff i should concider besides the piezoelectric effect if I wanted to swap out electrolytic capacitors for ceramic ones....

Retromaster · Post by **Retromaster** » Tue Jan 02, 2007 2:01 pm

well, I don't really no what difference it makes, but electrolyctic capacitors have polarity while ceramic don't. I'm not really concerned with the chemistry of this stuff when i'm building, but maybe someday it'll bite me. stay tuned as i might go get my 'for dummies' book.

sammy · Post by **sammy** » Tue Jan 02, 2007 6:25 pm

Electorlytic capacitors have both a capacity and an inducitvity because they consist of rolled up plastic with metal on top (rolled up metal =inductor) so it's not the same. It depends on what you are going to use the capacitors for but mostly you can't replace them.

hcmtnbiker · Post by **hcmtnbiker** » Tue Jan 02, 2007 9:32 pm

I was thinking of swaping them out in a NOAC circuit, and there's no more then 5 volts anywhere on the board so i figured it would be possible. Most of the caps from what i can tell are for smoothing out the current so i think it should work, tell me how i'm wrong.

codeman · Post by **codeman** » Wed Jan 03, 2007 12:17 pm

When it comes to behaving like an ideal capacitor, an electrolytic is pretty much the worst. The only reason they're so popular is because they're really cheap, and they can get very high capacitances per unit area when compared to other capacitor types.

Basically all i'm saying is that going from electrolytic to ceramic should be fine as long as you make sure the values are the same and the voltage breakdown of the ceramic is sufficient. You only really run into problems when going the other way around, replacing a ceramic cap with an electrolytic one can cause problems.

ArtemisGoldfish · Post by **ArtemisGoldfish** » Thu Jan 04, 2007 7:36 pm

If the electrolytic caps are of a very, very small capacitance (Like...low uF to high nF) then you can go ahead and replace them. If they're blue, you might not want to replace them, since as far as I can remember, blue are decoupling caps.

timmeh87 · Post by **timmeh87** » Thu Jan 04, 2007 10:35 pm

if anything you'd be better off with ceramic than electrolytic for decoupling.

like codeman said, electrolytics have pretty high ESR which slows down their response time.