One hundred years ago this month, the March 1926 issue of Boys’ Life showed how to build a crystal set for only 80 cents. And the radio editor, Zeh Bouck, even suggested some ideas for shaving that cost to a little less. (He also pointed out that the headphones could be had for $3.) Tuning was accomplished by a slider on the coil, and the author points out the importance of making sure the slider makes contact with only a single wire. One tip was to wind thread between individual windings.