I don't think that there is many usual applications for the function generator. I suppose that you might be able to test or simulate a component that sees or generates a square wave or pulse. I did use it yesterday to test 2 oscilloscopes. I wanted to see if the were capable of displaying a very narrow pulse at 8000 hertz. I was looking at Mechanic Mindset's post Don't be fooled crank sensor or oscilloscope. He was looking at a Mercedes crankshaft sensor with 8 pulses per revolution. I wanted to see what my scope would display. I was able to set the DM303 at 3% duty cycle and see a pulse on my OWON portable and Bench scopes. If there were a lot of missing pulses i would determine that my scopes cannot display such a signal and not condemn the sensor. I have an other function generator but it cannot vary the duty cycle. The OWONs did well at 8000khz. I could also check my graphing volt meters to see what they are capable of displaying. I hope this was helpful. Thanks for your comment.

Correction; I made a 60 times mistake. The frequency would only be 133 hertz. I was thinking 1000 RPM times 8 pulses. I forgot to divide by 60 to get seconds. I should retest all my meters to see what they would read at 133.3 hertz. I need to go back and look at Mechanic Mindset's video. I am not sure why any scope couldn't display that signal. It may be that i misunderstand what the sensor is outputting. I don't have a Mercedes to test.