Radio-Electronics Magazine, April 1949


Miss Mary Jane Padgett checks the charge on an electret.

The cover of Radio-Electronics magazine from April, 1949 shows a remarkably well-dressed young lady testing a new "electret" in a laboratory.

What's an electret, you ask? The simplest comparison is with a capacitor, which as you may know, has dielectric layers that can temporarily store an electrical charge. An electret also stores a charge, but the charge (polarization) is permanently embedded rather than transitory. The most familiar example is an electret microphone, which converts sound vibrations into electrical energy without using an external power supply.

The cover story describes a way to make electrets that were more stable and powerful than previous examples, using a mixture of Carnauba wax and hydrogenated resin.

More interesting to me was an article on page 34, entitled Magnetic TV Enlarger. The first illustration caught my eye because it shows a Pilot TV-37 television like mine. Furnished with a tiny 3-inch picture tube, the Pilot was often used with a magnifying lens to enlarge its picture.

The article describes a novel idea for enlarging the picture electronically rather than with a lens. Rather than spoil the punchline, I'll just let you read the rest and enjoy!


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