The young man shown here is working on his Morse Code skills thanks to a combination oscillator/blinker from the December 1943 issue of Popular Mechanics.

The set could make use of either a type 37 or 76 tube. Since both of these were older varieties, they were commonly found in discarded sets or the junk box.

The circuit ran on 6 volts, which could be supplied by either a car battery or four dry cells.