Busta Cap
Posted: Sat Aug 09, 2008 4:33 am
I swear my snake oil is good stuff.
This guy did some testing on a variety of Caps and posted about it. I was surprised how some of the caps reacted. Certainly didn't match my orginal gut feel.
http://www.wetterlin.org/sam/BypassTests.pdf
A quick overview, large electrolytic caps in a low pass filter tend to pass higher frequencies. Smaller ceramic caps tend to have a higher block band, and starts to block near where the electrolitic starts to pass frequencies again. Then at even higher frequencies, neither the ceramic or the electrolitic can block the frequencies.
So when attempting to prevent low and high frequencies, use both crappy electrolytic and ceramic's. Say the electrolytic blocks 1MHz to 10MHz, then the ceramic might get 10MHz to 100MHz.
Also keep temp changes in mind, as both are unstable relative to temp.
This guy did some testing on a variety of Caps and posted about it. I was surprised how some of the caps reacted. Certainly didn't match my orginal gut feel.
http://www.wetterlin.org/sam/BypassTests.pdf
A quick overview, large electrolytic caps in a low pass filter tend to pass higher frequencies. Smaller ceramic caps tend to have a higher block band, and starts to block near where the electrolitic starts to pass frequencies again. Then at even higher frequencies, neither the ceramic or the electrolitic can block the frequencies.
So when attempting to prevent low and high frequencies, use both crappy electrolytic and ceramic's. Say the electrolytic blocks 1MHz to 10MHz, then the ceramic might get 10MHz to 100MHz.
Also keep temp changes in mind, as both are unstable relative to temp.