THE salt-water cell powering this transistor radio has all the advantages of a dry cell, costs only pennies to make, and lasts for months. The complete radio receiver, with battery but less earphones, can be built for $3 or less.

As shown in the photos, the battery delivers about three-tenths of a volt. The radio consumes only 12 microamps while running, and in actual tests ran three days continuously without any detectable dip in volume.