A reader recently asked me what the top design rules were that they could implement on their product to maximize the chances of passing FCC and CE testing. There’s no doubt that there are countless ways to fail emissions and immunity tests, but a pattern of failure modes did emerge at my EMC lab.Regardless of the type of product I was testing, be it medical, industrial, … [Read more...]
A Report from the Southeastern Michigan EMC Fest
I recently attended the Southeastern Michigan EMC Fest, so this posting is dedicated to the show. I have a lot of admiration for Scott Lytle (Chapter Chair) and the Southeastern Michigan chapter he runs, so I decided to attend this year’s EMC Fest. The key attraction was Doug Smith, who gave attendees the benefit of his wisdom on diagnosing automotive EMC issues.The … [Read more...]
Linearization of EMC Amplifiers and Fixing the Broken Automotive Emissions Test Fixture
Read other posts in the "Elephant in the Test Room" series here.Linearization of EMC AmplifiersThis section of the posting got a little long-winded but it at least serves two purposes. It is a step closer to closing Elephant in the Test Room #2 ‘Disharmony in Harmonic Limits,’ and it also helps determine the linearization target on the TWT amplifier we are working with.The … [Read more...]
A Crossword Just for EMC
ACROSS3) and 6) down. If the walls have ears in this judge’s room, don’t expect a reply 7) and 8) across. EHT can cause this to light up the dark8) See 7) across10) A heck of a lot of power, apparently12) The theme of this crossword13) Germany’s own version of 12) across14) A few billion of these involved in 7) across16) With 15 down the bible of EMC since 1970 18) Abbreviated … [Read more...]
Elephant in the Test Room #3 – Fixing the Broken Automotive Emissions Test Fixture
Read other posts in the "Elephant in the Test Room" series here.Please note, regarding the fate of Elephant #2 – ‘Disharmony in Harmonic Limits’, it has now fallen under the umbrella of ‘Linearization of EMC Amplifiers’ and will be alluded to again during the part of the design exercise that determines practical harmonic levels. And so, with no further ado, onto a whole new … [Read more...]
Elephant in the Test Room #2 Continued and The Design Guide Article
Read other posts in the "Elephant in the Test Room" series here.Elephant #2 - Disharmony in Harmonic LimitsThe Room: RF immunity testingThe Elephant: The curbing of the contribution made by harmonics to a calibrated test-field varies wildly from standard to standard, and within standardsThe Culprit: Harmonic limits that are seemingly not well thought through, and / or are open … [Read more...]
Training the Intern and Elephant in the Test Room #2 Continued
Read other posts in the "Elephant in the Test Room" series here.Elephant #2 - Disharmony in Harmonic LimitsThe Room: RF immunity testingThe Elephant: The curbing of the contribution made by harmonics to a calibrated test-field varies wildly from standard to standard, and within standardsThe Culprit: Harmonic limits that are seemingly not well thought through, and / or are open … [Read more...]
Elephant in the Test Room #1 Continued – Linearization of EMC Amplifiers
Read other posts in the "Elephant in the Test Room" series here.Recap On this ThreadThe room: MIL-STD RF immunity testing – 1-18GHz 200v/mThe elephant: everyone in the room is aware that a significant fraction of the ‘calibrated’ 200v/m test field is actually created at the wrong test frequency.The culprit: notoriously high ‘start of band’ harmonics produced by all octave band … [Read more...]
They’re Everywhere, They’re Everywhere – Part II
In part one of this post, I noted that there are three primary EMC coupling problems that are associated with the green wire safety ground: 1. The green wire conducted noise current modulates the signal and shows up as a differential voltage change across the load.2. The green wire forms a pick-up loop and acts like a magnetic field antenna.3. The green wire loop acts as a … [Read more...]
The First Practical Approach to EMC for Functional Safety (EMC Risk Management)
Keith Armstrong Cherry Clough Consultants Ltd. There are now many standards on Functional Safety (Risk Management) that apply to relevant electronics, including IEC 61508 [1] and the standards developed from it listed in Section II of [2], and ISO 14971 [3]. They all require that EMI be dealt with, but complying with emissions and immunity EMC test standards, even using … [Read more...]
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