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Why didn’t I see this coming?

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The equipment should have passed the emissions scan. It should not be susceptible to this noise. The filter analysis said this was not a problem. The case should be an excellent shield. Why doesn’t this pass?

There are two statements I have heard about electromagnetic interference which are both related and true: EMC is the science and engineering of things that are typically not on the schematic [1], and EMI is often caused by issues of geometry [2]. The first statement speaks to the issues of parasitics, or cross coupling of energy due to magnetic induction or capacitance. The second says that the parasitics can be controlled or reduced if the proper routings and separations are maintained, and that once a degree of understanding about these coupling mechanisms is understood the control of them can be obtained.

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Are You Ready for Entry to China?

1308 F3 coverChina is becoming the largest consumer market in the world. Electronic equipment especially high-tech devices are most popular in China. An attractive market, yes, but are you prepared to enter this vast marketplace? Like any country in the world, China has its own regulations for electronic equipment. China Compulsory Certification (CCC) is the most widespread certification you need to overcome.

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The Value of Certification

1308 F5 coverWhat does “certification” mean to you? What is the value of becoming “certified?” The answer to this question has to include an answer to another question, “what is being certified?” In the electrostatic control arena, the world’s premier organization for education and standards development is the EOS/ESD Association, Inc.

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Systems EMC in Medical Electronics

1309 F1 coverConsidering EMC techniques during the design phase will minimize EMC problems and avoid disasters uncovered at EMC test time. At this time, the remedial measures are usually very painful.

In the typical case, where the electronic equipment is contained within a single enclosure, enclosure shielding along with cable filtering or shielding are commonly employed to meet EMC requirements.

The Basic Principles of Shielding

1403 F4 coverToday’s electrical and electronic devices are subject to mandatory EMC requirements throughout the world. Many devices operate at high frequencies and are very small. They are placed in nonconductive plastic cases providing no shielding. Essentially, all these devices cannot meet these mandatory requirements or they may cause interference to other devices or receive interference causing susceptibility problems without a proper program of EMI control. This program consists of identifying the “suspect” components and circuits that may cause or be susceptible to EMI. This is completed early on in the program to allow for an efficient design in keeping the cost of dealing with EMI as low as possible. A complete EMC program consists of proper filtering, grounding and shielding. This article will discuss the latter, but the other factors cannot and will not be ignored or given insufficient priority.

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Marking and Labeling

1309 F2 coverIt is common for every marketed product to contain some type of marking—label, silkscreen, engraving, stamping, or any combination of these four. Every safety standard has a section or clause that is concerned with marking. Among these markings, a label is the one that is commonly used in most products.

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EMC Lab Selection – Revisited

1310 F1 coverDesigners and manufacturers of electronic products are frequently faced with the question: “How do I find a high-quality EMC testing laboratory where I can confidently test my products?” The emphasis of the great majority of design and/or manufacturing entities is on obtaining (1) quality preliminary testing of EMC characteristics to refine the design of their products and (2) quality final design testing of their product for regulatory approvals. The final design, of course, is what gets manufactured and released to the general population for their use in daily life. This article is intended to aid designers and manufacturers in finding and utilizing high-quality EMC testing laboratories.

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Product Design: How to Get the Design Right the First Time

1403 product-design coverMany manufacturers design a product first, then attempt to “fix” the design later to meet the applicable safety standard. Prior knowledge of the applicable safety standard and its requirements for the product will help meet deadlines, keep design costs down, and result in a properly designed product.