Aboutcleggsan Expertise All technical areas of Electronics Engineering.
Experience BSEE, MBA, Design, R&D, University Research.
Senior Life Member of IEEE. Life Fellow of AES.
Organizations IEEE, Consumer Electronics Society, Audio Engineering Society.
Broad teaching experience; work experience mostly in consumer electronics and conversion from analog to digital technologies. Pioneer in digital audio at all levels.
Question QUESTION: Dear Mrs cleggsan,
I'm doing a final year project on harmonics control in low voltage applications such as analyzing the harmonics generated from a non linear load like a PC and filter the harmonics. To that end, I'm designing a filter bank tuned at those specific frequencies. My filter bank consists of notch filters using UAF42. I'm planning using comb filters. Can you give me some guidance for that. I think there are some ICs incorporating these comb filters.
Thank you
ANSWER: Here is a TI sheet on their 60Hz notch filter using their UAF42:
If you want to pull out the harmonics on the power line when a non-linear load is on the line you should use a standard harmonic distortion analyzer and take the output of it which is then easily analyzed either qualitatively on a scope or analyzed further with a DSP.
So, I am not so sure comb filters are the right thing to do be using in an instrument application.
That being said, here is some design ideas for your application:
Most of the ICs that I am familiar with are used in television receivers for video chroma enhancement and do not apply to low frequency harmonically related signal extraction.
is adaptable for use at low frequencies or not. I am guessing it is not.
Hope this helps out.
C
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QUESTION: Thanks a lot Mrs cleggsan, for answwering my questions. I would like to ask you one more thing. Do you know any link or where they have built workable and simple active filters. Those from the IEEE seems a little too advanced and complicated for undergraduate students. Active filters are supposed to produce a wave of opposite phase and cancel the incoming harmonics.
Thanks a lot
QUESTION: Dear Mrs cleggsan,
I bought the UAF42 IC and tuned it to give a notch filter of 150Hz, 250Hz, 350Hz, 450Hz, 550Hz. I tested the 150Hz filter with the signal generator and it works. The other filters are not working at all. Now, after 1 month, the 150 Hz filter also stopped working. im putting the filters in a filterbank which is connected to a 4V voltage provided by a 12V voltage divider fed from a stepped down transformer.
What could be the reasons that suddenly all filters stopped working? The filters are only in breadboard not yet converted to PCB
Thanks
Answer First, check the voltages and make sure all the dc levels look good.
Next put the scope on the IC and check out each pin for waveforms. If no waveforms, even tho voltages are correct, you may have a bad IC. Check the current drain, for example., Is it running hot? If too hot it may be burning up.
I think basic examination should tell you what is not working right. Could be a wire came loose or bad connection, etc. You can check it one by one since it is in breadboard config.
