Fuzz Buster

The days of fuzzy television may be numbered. Often this annoyance is the result of electromagnetic fields generated by other equipment, say, a vacuum cleaner that shares the circuit with the TV. Banishing the problem entirely would require prohibitively large and expensive versions of devices called filter capacitors. But MIT electrical engineer David Perreault and his colleagues have found a better way to fix TV fuzz and such similar problems as cell phone and car radio static. The approach calls for printing patterns of copper on the circuit boards that carry the filter capacitors. These patterns, called coupled magnetic windings, enhance the performance of the capacitors by generating a tiny voltage from magnetic fields associated with currents in the circuit. The voltage forces the currents to pass through the capacitor for filtering. The payoff: filtering that is 10 to 30 times more effective. And because the copper can be included in the standard manufacturing process at no added cost, “you get something for nothing,” says Perreault, who expects the technology to be commercialized within two years.