Pocket Edition

So far, no one had built a practical radio as small as a wristwatch.* But last week, a National Bureau of Standards physicist announced that scientists had come close. A tiny new "skeleton" set, no bigger than a pack of cigarets, could be hidden in the palm of one hand, said he.

The miniature set is a descendant of the famous proximity fuse--which was a complete transmitter-receiver in the nose of a 5-inch shell. Part of the secret is the dwarfish tubes, no bigger than lima beans. Part is the system of "wiring." Instead of the conventional radio's bulky tangle of wires, designers used lines of silver-bearing ink, printed accurately through a stencil on a small ceramic plate. The "resistors" are printed too, in carbon ink. The condensers are paper-thin discs of ceramics, silver-coated on both sides and stuck on the plate. Even the coils can be printed: they are nothing but spirals of delicate silver lines.

Problems that need some working on before the little wonder is manufactured in mass: a mobile source of power and an amplifier.

* But the Dick Tracy comic strip last week featured one.

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