[sdiy] Harmonic effect of rectification

[aankrom]

I'm going to jump in without reading all the replies first. Consider 
that unsymmetrical waves always have even-order harmonics and some have 
odd-order harmonics. Like when you use a two-diode string and a reversed 
diode to clip a waveform unsymetrically. The octave up effect happens 
when you use a fullwave rectifier because the wave-half traversing down 
is flipped up making a wave of twice the frequency, but with other 
harmonic components was well because it is an unsymmetrical wave. I have 
always wondered if there was a simpler waveform to visualize a rectified 
sinewave that had the same harmonic components, but with different phase 
relationships (just like an up-ramp and a down-ramp have the same 
harmonics, but different phase relationship - 180 degrees. They sound 
virtually the same to the ear.) Full-wave rectified power supply hum has 
120Hz, less 240Hz, even less 480Hz... (100Hz, 200Hz & 400Hz for the 
folks in the UK & Europe...) It seems like there should be some 
odd-order harmonics...

I hope that didn't sound like rambling.

AA


On Fri, 20 Apr 2012 13:59:15 +0100, Neil Johnson wrote:
> Hi,
>
> Richie Burnett wrote:
>> Thinking of sinewave rectification as amplitude modulation by a 
>> squarewave might
>> help you to figure out where all those harmonics come from.
>
> This guy has a good take on it:
>
> http://www.youtube.com/watch?v=tCZdVu3TfUs
>
> (parts1 and 2)  Sorry its a bit mathsy Tom, but he does show quite a
> few maths tricks to keep things simple too.
>
> Cheers,
> Neil