Electronics: Fun & Fundamentals
Written and photographed by Charles Platt
Time Required: 1 Hour Cost: $10–$20
THE MICROPHONES IN OLD-FASHIONED WIRED TELEPHONES were relatively heavy, large, and expensive, and their sound quality was terrible. Thanks to materials science developments in the 1990s, electrets are now tiny, high- quality, and available from some sources for less than $1 each.
The electret microphone performs its magic with a pair of thin electrostatically charged membranes. When sound ...