EEVblog Electronics Community Forum
EEVblog => EEVblog Specific => Topic started by: EEVblog on April 25, 2014, 01:23:27 pm
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Part 3 of microphone technology with Doug Ford, former head designer at Rode Microphones.
This video discusses both regular condenser and electret condenser microphone construction and physical properties.
All videos in this series are here: https://www.youtube.com/playlist?list=PLvOlSehNtuHv98KUcud260yJBRQngBKiw (https://www.youtube.com/playlist?list=PLvOlSehNtuHv98KUcud260yJBRQngBKiw)
EEVblog #608 - Condenser & Electret Microphone Construction (https://www.youtube.com/watch?v=yKOH0DyRWRU#ws)
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For pre-polarized microphones, I don't think there is a static charge on the Teflon (or other polymer film), but I might be wrong. Don't they simply fabricate the films in the presence of an electric field, which aligns the dipoles in the polymer? As the Teflon cools and crystallizes, the dipole direction is locked in. Or do they actually charge one surface by spraying an electron beam onto the film?
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As a follow-up, the wiki article on microphones has a confused description of "permanently embedded static electric charge (which, due to the high resistance and chemical stability of the material,..." But then they talk about dipolar alignment, which is not the same thing as a static charge. The decay of dipolar alignment has nothing to do with high resistance. It depends on how easily the polymer chains can re-orient. On the other hand, decay of a static charge would depend on resistance. So, which is it?