This simple code practice oscillator appeared 75 years ago this month in the December 1944 issue of Radio Craft. The idea was sent in to the magazine by William McGee of Baltimore, MD, who noted that the idea required fewer parts than most other oscillators. The idea was self-explanatory, as it used “the principle of feedback which all sound men have to combat.” It consisted of a microphone set in front of the speaker of a radio. If the set had a phono jack, it could be connected there. If not, the submitter showed where to wire it into the radio.