Publisher Summary The section deals with the last flight, the check-ride, with the FAA examiner, which seems to be time of great tension and a little fear. It is a flight meant to summarize all the phases of flight, where it is asked to put all the knowledge that has been gained during the training into practice. This section explores the possibility of producing audio signals using, Output Compare modules of the PIC24. When in the pulse width modulation (PWM) mode and in combination with more or less sophisticated low-pass filters, the Output Compare modules can be used effectively. It is rather used as digital-to-analog converters to produce analog output signals. If it is managed to modulate the analog signal with frequencies that fall into the range that is recognized by the human ear, approximately between 20 Hz and 20 kHz. The pulse is produced at regular intervals (T) typically provided by a timer and its period register. The pulse width (Ton) is not fixed but is programmable and it could vary between 0% and 100% of the timer period. The ratio between the pulse width (Ton) and the signal period (T) is called the duty cycle.