Terry: The voltage on the coil is only sinusoidal for the case with no top loading, such as by a sphere or toroid. With enough top loading the voltage should rise linearly from the base (at least if there's no discharge taking place). Ed P.S. Will fire up the PC and download your work. I happen to be a QBasic fan, but that's a matter of taste and the "big boys" seem to be favoring languages like C+++, of which I am totally ignorant.