A few months ago, we posted about the history of the “foxhole radio,” a crystal set made with a razor blade detector, As reported in the New York Times in June 1944 and Time Magazine in July, soldiers at the beachhead in Anzio made these receivers to pass the time. The receiver was later popularized in Jack Gould’s book All About Radio and Television.
Among those to see the plans was Radio Craft editor Hugo Gernsback. In the September issue of Radio Craft, he pointed out that the original Razor Blade Radio Detector had actually been published by him, in the January 1909 issue of Modern Electrics. He also shows two other similar detectors published in 1906.
The 1909 razor blade detector actually differed from the “foxhole” version, however. The Modern Electrics detector uses two razor blades with a pencil lead balanced on top. The razor blade seems to be serving the function of “cat’s whisker,” as opposed to being the crystal in the foxhole version.