[sdiy] Question about "Musical Applications of Microprocessors" book

[ebrombaugh1 at cox.net]

Look closely at fig 1-6 and you'll see that he's not synthesizing a pure 50% duty-cycle square wave, but rather a rectangular pulse wave with about 30%. Since 50% is the only case for which all even harmonics disappear, this diagram is not incorrect.

Eric
  
---- Sam Ecoff <secoff at execpc.com> wrote: 
> Hi Gang,
> 
> So, at the kind advice of the list, I'm wading through "Musical  
> Applications of Microprocessors". Very enlightening, and very  
> enjoyable! I have a question, though. I was always taught that square  
> waves were composed of only the odd harmonics. I believed that meant  
> you *wouldn't* have a harmonic an octave higher than the fundamental,  
> but on pages 23-25, it shows the process of creating a square wave by  
> adding sine waves, one of which has a frequency which is double that  
> of the fundamental. I have also noticed that while some books count  
> the fundamental as the first harmonic, others treat an octave higher  
> as the first harmonic. Regardless of which system, the info in the  
> microprocessors book doesn't seem to work as they also show that you'd  
> have to combine a sine wave whose frequency is three times the  
> fundamental to get a square wave. What am I missing here?
> 
> Thanks!
> 
> Sam E.
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