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Interference Technology

For EMI / EMC Engineers

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Shielding

Shielding Design Flow Chart

 

The flow chart in Table 1 will assist the designer in selecting the appropriate shielding options necessary to meet their shielding and environmental requirements. The shielding requirement flow chart begins by identifying the type of NEMA or IP enclosure based on the intended environment (indoor/outdoor, military/commercial, marine or land/desert). Then, using the resulting … [Read more...]

Some of the Many Stories of Medical EMI

 

Introduction I have been collecting stories about EMI for a long time, publishing many of them in the ‘Banana Skins’ column of The EMC Journal, www.theemcjournal.com. Some come from official reports, some from anonymous whistleblowers, some are amusing, and some concern deaths and injuries. At the present time, I have published 855 of them, all indexed by application and by … [Read more...]

EMI Basics and Board Level Shielding Design

 

Introduction In today’s world full of digital electronic devices, electromagnetic interference (EMI) is a major concern in both military and commercial marketplaces. Electrical equipment can become susceptible to these undesirable emissions and malfunction due to their presence. The simplest and most cost-effective method for reducing EMI is to first attack it at the board … [Read more...]

Can 5G Sites Be Good Neighbors?

 

Baseball Hall of Famer Yogi Berra was notable for his skill on the field and was equally notable for many of his quotes. “Yogi-isms” were things he often said that were both amusing and insightful. Referring to a popular restaurant, he said, “Nobody goes there anymore; it’s too crowded.” Sounds like a contradiction, but it’s easy to follow his meaning. Customers chose not to … [Read more...]

Drag Races, a Cashless Society, and the Threat of EMP

 

About a month ago, my 12-year-old son and I made his first-ever trip to the NHRA Drag Races near our home. It’s something that I always did with my dad, and I have looked forward to taking him ever since he was born. It’s a typical father-and-son day, wrought with loud, fast cars, terrible food, and the occasional waft of nitromethane fuel in the air. The drive is about … [Read more...]

Essential Performance for Medical Products

 

Introduction Essential Performance has been a mysterious term ever since its introduction in International Standard IEC 60601-1-2 in 2001. Essential Performance is not unique to IEC 60601-1-2, but originates in the general standard, IEC 60601-1, and is used throughout all the collateral and part 2 standards of the IEC 60601 family of standards for medical electric equipment, … [Read more...]

Design for Compliance Essentials

 

INTRODUCTION While unrealistic to discuss all aspects of product design in a single article, I’ll try to describe the most common design issues I find in the hundreds of client products I’ve had a chance to work on. These issues generally include PC board design, cables, shielding, and filtering. More detailed information may be found in the Reference section below. As … [Read more...]

Filter Installation Issues Pt. 3: Mounting and More

 

This article is the 3rd and final part of a three-part Filter Installation Issues series. Read Part 1: Input and Output Conductors here. Read Part 2: The Synergy of Filtering and Shielding here. There are now many suppliers of PCB-mounted shielding-cans that can be used with three-terminal filters, and they have many types that can be automatically assembled like any … [Read more...]

How to Specify Board-Level Shielding

 

The Purpose of Board Level Shields Board level shields (BLS) are generally small metallic shielded boxes mounted directly to PC board ground return layers. There are three primary purposes of board level shields: Isolation of sensitive circuitry from other noisy circuits on the board Trapping the emissions from noisy circuits on a board from propagating to the outside … [Read more...]

Filter Installation Issues Pt. 2: The Synergy of Filtering and Shielding

 

This article is part 2 of a three-part Filter Installation Issues series. Read Part 1: Input and Output Conductors here.  Some mains filter manufacturers only design and specify their filters to provide attenuation over the frequency range of the conducted emissions tests (typically up to 30MHz for commercial and industrial products), to keep costs low. Unfortunately, if … [Read more...]

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