If you want calculators for impedance of traces on PC boards, check out http://www.ultracad.com. Otherwise, what is it that you want? Carl Van Wormer Cipher Systems 1815 NW 169th Place, Suite 5010 Beaverton, OR 97006 Phone (503)-617-7447 Fax (503)-617-6550 -----Original Message----- From: Mauro, Dan [mailto:[log in to unmask]] Sent: Friday, March 15, 2002 5:28 AM To: [log in to unmask] Subject: [TN] Impedance calculator Does any one know a good tool to model impedance calculations.