Normally you would do this with a low-pass filter. On Fri, Nov 16, 2012 at 12:19 PM, Manu Abraham wro= te: > Hi Scott, > > On Fri, Nov 16, 2012 at 10:27 PM, Scott Dattalo wrote= : >>> In a push pull H bridge configuration, aren't the even harmonics >>> supposed to get cancelled ? >> >> The even harmonics of a square wave are cancelled only if the duty cycle >> is 50%. In general, the harmonics have the component: sin(n*pi*d), where= n >> is the harmonic number and d is the duty cycle. For 50% duty cycle, only >> the odd harmonics are present. For a 1/3 duty cycle, every third harmoni= c >> is cancelled. > > > Thanks for the detailed info. > > I have a sine table over here, for which it's entries are a sinusoidal > variation > of the duty cycle. > > viz: > > 0, 2409, 4794, 7134, 9404, 11585, 13653, 15590, > 17377, 18997, 20433, 21673, 22704, 23517, 24103, 24457, > 24575, 24457, 24103, 23517, 22704, 21673, 20433, 18997, > 17377, 15590, 13653, 11585, 9404, 7134, 4794, 2409, > > Looking at the output spectrum, I can see all the harmonics, including th= e > fundamental, with amplitude gradually reducing for the higher order harmo= nics. > > Is there any way that I can eliminate the harmonics, leaving the fundamen= tal > as is ? > > Thanks, > Manu > -- > http://www.piclist.com PIC/SX FAQ & list archive > View/change your membership options at > http://mailman.mit.edu/mailman/listinfo/piclist --=20 http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist .