1. The problem statement, all variables and given/known data http://i.thespiffylife.com/files/1/trans1.jpg [Broken] i have to find Vc(t) 2. Relevant equations I know that Vc(0+) = Vc(0) = Vc(0-) and Vc = Vs*e^(-t/RC) 3. The attempt at a solution What i'm unsure on is what the equivalent resistance of the circuit would be so I could find the time constant. I know since the Capacitor is fully charged it now behaves as a voltage source, but for any nodal / mesh equation I come up with I'm always one equation short of having equal unknowns & equations. So ... any help on how to find the Req would be nice.