# is second harmonic practically zero

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#### avlsi

##### Member level 3
Is second harmonic practically zero. what is the typical value ? is it arounf (0-2) or else in the order of 0.001

Does that turn out to be in -ve on the dB scale.

#### v_c

Second harmonic of what type of waveform are you referring to?

If you have a perfect sinewave, yes the second harmonic is exactly zero.
If you look at an outlet on your wall, you should have a pretty good sinewave and you will have some harmonics but yes, the second harmonic in that case should also be very small.

Let's say you have a sinewave and you put it through a full-bridge rectifier. The output of the full bridge rectifier are waveforms that look like the waveform on the right.

That rectified waveform on the right will have a substantial 2nd harmonic, it will also have a dc value. However, the rectified sine wave will not have any fundamental frequency components. Fundamental frequency being the frequency of the input sinewave (on the left).

Best regards,
v_c

#### keith1200rs

##### Super Moderator
Staff member
A sawtooth waveform has a lot of second harmonics. With a 1V peak amplitude (2V peak-peak) the output is 0.64 fundamental, 0.32 second harmonic I think.

Keith.

sinoo_jahagirdar

### sinoo_jahagirdar

Points: 2

#### permute

for a periodic waveform, even-ordered harmonics correspond to the symmetric portion, while odd-ordered harmonics correspond to the anti-symmetric portions. Most common test signals have no intentional even-ordered harmonics. PWM signals with a duty ratio other than 50% will have both even and odd harmonics.

If you want test signals with lots of even harmonics, you should aim for signals that are periodic, but lack any obvious symmetry.

sinoo_jahagirdar

### sinoo_jahagirdar

Points: 2

#### sinoo_jahagirdar

##### Newbie level 6
Thanks keith..ya i have simulated all the waveforms (incl. sawtooth waveform) using fourier series.Got the 2nd harmonic value but practically i need to generate sawtooth waveform to synchronize with the mail ckt...

---------- Post added at 05:55 AM ---------- Previous post was at 05:52 AM ----------

thanks . will try it n cme back 2 u soon for further doubts : )

---------- Post added at 05:56 AM ---------- Previous post was at 05:55 AM ----------

thanks . will try it n cme back 2 u soon for further doubts : )

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