High 3rd harmonic on the neutral

Chris Pearson:

Denis McMahon:.

Higher harmonics can also add, but they are less of an issue because they are much smaller.

I gave this more thought as I was clipping my yew hedge this afternoon.


A flute produces something near a sine wave, but a clarinet does not. However, if the magnitude of any harmonic were greater than the fundamental, would that frequency not be the fundamental?


I then wondered what would happen if all the current were at the third harmonic. It seems fairly clear that now we simply have a supply at 150 Hz.


. . .

Isn't gardening therapeutic! Many of my inspirations come when I am in the shower.


Anyway, taking the points on sound waves. The sound of a clarinet is stronger in harmonics than that of a flute, so its waveform is less like a sound wave. The oboe gives even richer harmonics, thus more of a piercing sound. Now take a quite different instrument, the violin, where the harmonics are so strong and ordered that it is almost saw-tooth in shape.


If a harmonic had greater magnitude than a fundamental, would it not be the fundamental? My answer would be "no". The fundamental is by definition the lowest frequency. It usually has the largest amplitude but this does not need to be so. A telephone line cannot handle frequencies less than 300 Hz so low harmonics are suppressed. This makes a voice over the  phone sound "thin". The fundamental of the human voice is less than 300 Hz; male speech fluctuates around 100 Hz. But the fundamental effectively "modulates" the higher harmonics. These modulations are heard over the telephone, and the brain can interpret them to derive the fundamental. So if, for example, someone sings over the phone, we can follow the fundamental pitch.


What if all the current were at the third harmonic? The harmonics are produced as a result of the response of the circuitry to the fundamental frequency of the supply p.d.  The only way I could see all three phases at 150 Hz would be if that were the supply frequency. In which case, they would be fundamental frequencies, cancelling one another if equal, and the third harmonics would be 450 Hz.

 

Chris Pearson:

Denis McMahon:.

Higher harmonics can also add, but they are less of an issue because they are much smaller.

I gave this more thought as I was clipping my yew hedge this afternoon.


A flute produces something near a sine wave, but a clarinet does not. However, if the magnitude of any harmonic were greater than the fundamental, would that frequency not be the fundamental?


I then wondered what would happen if all the current were at the third harmonic. It seems fairly clear that now we simply have a supply at 150 Hz.


. . .

Isn't gardening therapeutic! Many of my inspirations come when I am in the shower.


Anyway, taking the points on sound waves. The sound of a clarinet is stronger in harmonics than that of a flute, so its waveform is less like a sound wave. The oboe gives even richer harmonics, thus more of a piercing sound. Now take a quite different instrument, the violin, where the harmonics are so strong and ordered that it is almost saw-tooth in shape.


If a harmonic had greater magnitude than a fundamental, would it not be the fundamental? My answer would be "no". The fundamental is by definition the lowest frequency. It usually has the largest amplitude but this does not need to be so. A telephone line cannot handle frequencies less than 300 Hz so low harmonics are suppressed. This makes a voice over the  phone sound "thin". The fundamental of the human voice is less than 300 Hz; male speech fluctuates around 100 Hz. But the fundamental effectively "modulates" the higher harmonics. These modulations are heard over the telephone, and the brain can interpret them to derive the fundamental. So if, for example, someone sings over the phone, we can follow the fundamental pitch.


What if all the current were at the third harmonic? The harmonics are produced as a result of the response of the circuitry to the fundamental frequency of the supply p.d.  The only way I could see all three phases at 150 Hz would be if that were the supply frequency. In which case, they would be fundamental frequencies, cancelling one another if equal, and the third harmonics would be 450 Hz.