Abstract: A circuit for providing protection for power factor correction (PFC) boost converters from conditions such as input voltage surges that can otherwise cause failure. The circuit also prevents unnecessary down time of the boost converter after a power failure or on startup. The circuit detects the real time rectified input voltage and provides a real time comparison of the detected input voltage and the output voltage. The boost function is controlled as a function of the comparison. The circuit enables the boost converter to start and restart more quickly, even before the output voltage becomes stabilized, since boost is permitted as soon as the output voltage exceeds the real time sampled input voltage. By enabling boost during this period, the circuit eliminates the need to wait at least a few cycle times until the output voltage is higher than the peak of rectified input voltage.

Abstract: A soft-start circuit for a power converter including a switch controlled to cause the soft-start interval for the converter to be terminated when a predetermined condition is fulfilled. The predetermined condition is preferably the output voltage of the converter stabilizing at its normal operational level. The soft-start circuit detects when the predetermined condition is fulfilled and enables the converter to more rapidly recover after the initiation of a soft-start. In a preferred embodiment, the soft-start circuit includes a protection circuit for adjusting the soft-start voltage linearly as a function of the duration and magnitude of an overcurrent condition at the output so as to provide a scaled level of protection for the converter.

Abstract: A circuit for protection of the operation of power factor correction (PFC) converters from conditions such as input voltage surges that can otherwise cause failure, and to prevent unnecessary down time of the boost converter after a power failure or on startup. The circuit detects the real time rectified input voltage and provides real time comparison of the detected input voltage and the output voltage. The boost function of the PFC is controlled as a function of the output of the comparison circuit so as to quickly inhibit the boost function of the PFC controller thereby disabling boost and protecting the circuit from burning out. The circuit enables the PFC to starts and restart more quickly, even before the output voltage becomes stabilized, since boost is permitted as soon as the output voltage exceeds the real time sampled input voltage.

Abstract: Templates are used in methods of improving the perceived intonation of musical notes by modifying each note to provide certain frequencies between adjacent pairs of notes. The template modifications provide, in a sequence of twelve notes per octave, or extended octave, that each note is separated from an adjacent note according to one of frequency ratios of 25/24 (h), 16/15 (m) and 27/25 (s). The templates can be used with keyboards and virtual keyboards and applied to recorded music, musical input signals, or data, as required.