The plans for this code practice oscillator appeared 80 years ago in the September 1946 issue of Radio News. It employed a single 117N7 tube, and put out one watt of audio, which was said to be “loud enough to drive any family out of the house..” It did, however, contain a volume control, just in case that wasn’t desired.

The entire circuit was built into a wall cabinet, with rubber feet on the corners. The magazine assured that with this cabinet, “the code practice oscillator is nice enough looking to be left around on the living room table without incurring the wrath of the ladies of the house.”