Update: Based on Ray's input I tried different combinations of resistors and capacitors at my disposal to try different cutoff frequencies. Also, I replaced the Arduino with a datalogger to read the output voltage. See the attached image for the results at different duty cycles (25kHz and 5.25Vpp). As before, we see the output drop from 5.2V to 0V between 100% and 50%. However, it is interesting to observe the that voltages become negative at 30% and 0% and mirror the magnitudes at the positive end.
Have a look and let me know what you think.
