Marko Rodin Coil -- 007 Device

[minnie]

   If you try "Allaboutcircuits square wave" there's a lot there that seems to
agree with Poynt's point of view.
    Just having a little break from wielding my 14lb. sledge hammer.
           John.

[tinman]

Brad,

I'm curious if you read this and if you watched the animation?

Does it make sense?

I tried to open the animation folder,but it says it is invalid or corrupt.

Quote: A square wave is a non-sinusoidal periodic waveform (which can be represented as an infinite summation of sinusoidal waves.
An infinite amount of sinusoidal waves would just be a solid block--a wave form that occupies all space. This is becoming more confusing--not easier.


Brad

[poynt99]

Yeah, the zip didn't work for some reason.

Well, the animation is on the web page I linked to.

An infinite amount of sinusoidal waves would just be a solid block--a wave form that occupies all space. This is becoming more confusing--not easier.

You need to look at it a different way than you are.

I seems you are envisioning a whole mess of equal amplitude sine waves drawn on an x-y plot. That is a start but you need to take a couple of more steps to get there.

Draw a sine wave with amplitude 1V. Now on the same plot draw a sine wave triple the frequency and 1/3 the amplitude. Next, draw a sine wave of 5 times the frequency and 1/5 the amplitude. Break the x axis into say 100 points. At each x point you add the y values of the fundamental and the 3rd and 5th harmonics that you drew. The progression should look like the attached pics if you were to add the fundamental and 3rd together first, then the 5th . See how it is becoming square-ish?

As you keep adding more and more harmonics (7, 9, 11, etc), it becomes more square.

[picowatt]

I tried to open the animation folder,but it says it is invalid or corrupt.

Quote: A square wave is a non-sinusoidal periodic waveform (which can be represented as an infinite summation of sinusoidal waves.
An infinite amount of sinusoidal waves would just be a solid block--a wave form that occupies all space. This is becoming more confusing--not easier.


Brad

I have not looked at .99's zip file but if it says the above, just ignore that for now and go with the "contains an infinite number of odd harmonics" definition.  This assumes, of course, that you are dealing with a perfect square wave as I previously discussed.

Just think of all the crazy 1kHz waveforms you can create using your FG by selecting sine, triangle, or square wave and messing about with the duty cycle and rise/fall times.  All those different waveshapes and yet your scope and FG continue to just readout 1kHz.  The difference between each waveshape is the additional, higher than the 1kHz fundamental, harmonics/frequencies contained in each waveform.

I believe your FG has two channel outputs.  You could combine a 1kHz sine wave (fundamental) from one channel with a 3kHz sine wave (3rd harmonic) from the other channel and begin to see a square wave develop.  If you could continue to add additional odd harmonics (or at least imagine doing so), each additional harmonic would fill in a bit more of the observed ripple.  5 harmonics makes a pretty good looking square wave, but as they say, the more the merrier...   

I do not believe that as an experimenter, this concept is going to "click" with you until you see evidence of it for yourself.  Consider performing the simple tests I have described using an audio graphic equalizer.  I think it will help solidify the concept.

You should also become familiar with the FFT function on your scope.  Feeding various waveforms from your FG into your scope's FFT function will reveal the additional frequency content of any particular waveshape. 

It would be time well spent...

PW

[picowatt]

Yeah, the zip didn't work for some reason.

Well, the animation is on the web page I linked to.
You need to look at it a different way than you are.

I seems you are envisioning a whole mess of equal amplitude sine waves drawn on an x-y plot. That is a start but you need to take a couple of more steps to get there.

Draw a sine wave with amplitude 1V. Now on the same plot draw a sine wave triple the frequency and 1/3 the amplitude. Next, draw a sine wave of 5 times the frequency and 1/5 the amplitude. Break the x axis into say 100 points. At each x point you add the y values of the fundamental and the 3rd and 5th harmonics that you drew. The progression should look like the attached pics if you were to add the fundamental and 3rd together first, then the 5th . See how it is becoming square-ish?

As you keep adding more and more harmonics (7, 9, 11, etc), it becomes more square.

In my previous post #123 I stated that the 3rd harmonic was 2/3 the level of the fundamental.

Funny thing is I originally wrote 1/3.  I was thinking in decibels and that the 3rd harmonic is down close to 10dB, which is roughly a factor of three, and had it right the first time.  By the end of my long winded post I changed it to 2/3 for some unexplainable reason.  Brain fade I guess.

.99 is of course correct, the level of the 3rd harmonic will be 1/3 the fundamental (close to 10dB down).

I am going to calmly write off the error to old age and the onset of dementia...

PW