1957 Self-Powered Radio

1957SeptRadioElectronicsThe little circuit shown here appeared sixty years ago this month in the September 1957 issue of Radio Electronics magazine. Almost anyone who has experimented with electronics has probably tried a variation of this circuit. It’s simply a way to run a small electronic device from the “free” energy of a nearby broadcast station. The signal is picked up by the antenna, is rectified by a diode, and the resulting energy is used to provide power to a transistor audio amplifier.

The example shown here appears to use a single diode to both provide power to the transistor, and the signal. According to the magazine, the diagram comes from U.S. Patent 2777057, issued to one  Jacques J. Pankove, and assigned to RCA.  While the patent contains drawings for circuits that are slightly more complex, the diagram here does not appear in the patent itself.

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