|The Electrad Diode was introduced in 1923, and was intended for detector use (mainly as a replacement for crystal detectors). It was no more sensitive than the crystal detector, but it was more stable and required minimal adjustment. The Fleming patent expired in 1923, and manufacturers quickly took advantage of this event. The Electrad Diode appears to have sold fairly well, as they are not especially rare today.
|This advertisement appeared in the July, 1923 issue of Radio News magazine.