>> A quick simulation suggests approximately 1.6 volts pk-pk >> with the output unloaded, assuming 5v pk-pk input. >> > >that's interesting, how did you simulate that? (n00b hat on) A good way to simulate such circuits is with Switchercad III from Linear Technology. http://www.linear.com/company/software.jsp -- http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist