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(link to Chuckey stmt) - SMPS EMI reduction techniques

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Full Member level 6
Sep 16, 2010
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In this thread Chuckey said.

"As an RF engineer I am constantly amazed by the thin leads and marginal designs of the new medium power low frequency transmitters ( SMPSs), if it was in a RF transmitter there would be 5 capacitors returned to a 3 mm ali chassis."

I do not fully understand this statement. It sounds like some kind of grounding but from what part of the circuit and what capacitor and connected to the aluminum chassis how? And thin leads where?

If anyone has some Perls of wisdom on lowering EMI on SMPS with secret grounding techniques i would love to learn.

Solving EMC / RFI issues is mostly the preserve of experienced power electronics and RF engineers...there are loads of tips and tricks related to isolating the problems and solving them, but they are all heavily application specific, a good PE engineer can recognise the cause and solve most if not all of the issues in a few days...

Well i would like to be a good PE engineer and learn these things but i have no one to learn from. Information is very sparse on the internet.

The EMC "problem" is nothing new, its been around for over a hundred years.

Like all engineering disciplines, there is a solid bedrock basis of theory, and a long history of empirical knowledge and practical experience that has built up gradually over time.

Bell Telephone Labs started to study the subject very seriously when long distance telephone circuits started to suffer from noise and interference back since about the 1930's.

One of the Bell Telephone Engineers, Henry Ott, decided to assemble all the known knowledge and techniques published in many diverse papers and publish a book.
This original book became required reading for trainee Bell Engineers and others outside Bell, that had particular interest in EMC techniques and topics.

Its been rewritten and expanded over the years and has never been out of print.
Highly recommended reading by any hardware, power electronic, or RF Engineer.
If you google the author, Henry Ott you should be able to find sources for his books both new and second hand, and also reviews.

Its not an inexpensive book, but it is an absolute gold mine of information for anyone seriously interested in EMC and related topics.

Just only now discovered that is all now available for free download:
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