This is a very common phenomenon in all circuit analysis specially in AC, that harmonics get into circuitry and we have to work around with an RLC combination to smooth things out. And this is one of the reasons ideal components differ from real time scenarios.
The perspective of harmonics is wide but as in daily techy life and specially on WP. The main harmonics are usually discussed in UPS output and Phone lines. I usually think of SNR and attenuation of a phone line to be something associated with environmental factor more then of equipment and technology. This is mainly due to the line arrangement as well as poor knowledge of harmonics and attenuation from vendors end.
In UPS etc we face the same issue while getting a dirty sine wave on the output side. And that is clearly depicted by the sound coming out of fans and speakers.
The purpose of this thread is to discuss the knowledge of circuit analysis we posses whether its RLC combinations in clearing out these noises, or band pass filters etc. Use this knowledge and discuss ways of solving some common problems such as variable SNR margins and humming sound from speakers etc.
I believe there are few combinations that when used with individual devices, can help them work normal. The way Ijaz Ahmed, Asad and others helped in making things like inverters for routers and stuff like these, can also be used in this thread. I know its getting long But the beauty of this thread would be to discuss real time Local issues.
Hope this fancies someone and we could have some constructive discussions going on.