Introducing The Acoustic Prism

The traditional optical prism has a new family member. Engineers have created the acoustic prism, and it's exactly what it sounds like.
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Fifty-Year Old EMI Testing Problems Solved!

There have been inherent problems with audio frequency conducted susceptibility tests since their inception. These are: ensuring that the injected signal drops across the test sample; monitoring the signal that is developed across the test sample, both from the point-of-view of isolating the instrumentation so it doesn’t ground the input power return and, more problematically, monitoring injected ripple riding on an ac bus potential. These issues are resolved using a novel but inexpensive transducer described herein.


EMC Archaeology: Uncovering a Lost Audio Frequency Injection Technique

Injection of audio frequency ripple on equipment input power conductors has a long history, going back to 1953 (MIL‑I‑6181B) in the United States military, and at least as far back as 1961 in commercial aviation (RTCA/DO‑108). Audio frequency injection has been accomplished by inserting the secondary windings of a coupling (isolation) transformer in series with the power conductor to the test sample. While various transformers had been used prior to the 1960s, one has become standard since 1963. That Model is the Solar Electronics Model 6220, designed in 1962 and accepted by the United States Air Force in 1963 as being superior to previously used injection transformers. [1]