Crystal Radios / Fox Hole Radios: For me, it all started here | N6CCAbove: Showing the detail of the safety pin used to hold the pencil lead against the razor blade. The copper wire connects the “lead” to the safety pin and the antenna circuit. This assembly functions as the “Cat’s Whisker” of classical crystal radios. My cat was especially appreciative of this alternate design.
自作コンパウンドクロスボウの作り方 How to make homemade PVC compound crossbow - YouTube