On Sun, Dec 12, 2004 at 09:54:14AM +0000, Karel Kulhavy wrote: > On Mon, Aug 23, 2004 at 09:33:31PM -0400, Dan McMahill wrote: > > On Sun, Aug 22, 2004 at 06:13:34PM +0000, Karel Kulhav? wrote: > > > Hello > > > > > > MMI promises to compute distributed paramteres of copper strips on > > > PCB. > > > > looks neat once it can be built. I've started and found some issues > > with the build system. Haven't fixed them all yet... > > > > > > > I am lured by an idea of computing how many picoforad 1cm^2 of PCB trace > > > on my > > > 1.5mm FR-4 board makes. > > > > try out mcalc.sf.net to find impedance (sqrt(L/C)) and velocity > > (1/sqrt(LC)) of > > your line and then solve for L and C. > > Yes it works thanks. > > > > > Thats useful for lines which are relatively long compared to their width. > > for a simple parallel plate thing like what you have, you can > > > > a) note that 1cm is a good bit more than 1.5 mm so just use C = eA/d > > (e = permitivitty of FR4 which is around 4.8x free space permitivitty) > > (A = area) > > (d = distance) > > > > or > > > > b) use something like fastcap if you want a more accurate field solution. > > Don't you know where to download it's files? > I didn't find it on freshmeat and opencollector.
Here's a good collection of links (including fastcap): http://www.fastfieldsolvers.com/links.htm What problem are you trying to solve ? -- Daniel Nilsson
