The invention is a combination spool and bobbin holder having essentially separate sections for the spool and the bobbin. At least one comparator is configured to provide an error signal to the pulse modulator based on a comparison between an output signal generated by the power supply and a feedback signal generated in response to the application of energy to tissue. In particular, the calendar user interface provides options to the user to individually select a range or non-contiguous time periods and to specify time periods relative to a current time period where the relative time periods are internally converted to fixed time periods.