Positive feedback, or regeneration, played an important part in radio engineering during the two or three decades following its development for electronic circuits around 1912–15. This paper reviews the earlier history of the subject, considers the controversial inventions of 1912–15 in some detail, and goes on to examine some other applications of positive feedback in self-oscillating detectors, e.g. the autodyne, the homodyne and the super-regenerative receivers.