If you read the December 1970 issue of Mechanix Illustrated, you’d be treated to [Len Buckwalter]’s crystal radio build. He called out Modern Radio Labs as the supplier for parts. That company, run by [Elmer Osterhoudt], got so many inquiries that he produced a kit, the #74 crystal set. [Michael Simpson] found an unopened kit on eBay and — after a bidding war, took possession of the kit. The kit looked totally untouched. The crystal detector was still in the box, and there were period-appropriate newspaper wrappings.

The kit itself isn’t that remarkable, but it is a classic. An oatmeal box serves as a coil form. There’s a capacitor, a crystal detector, and headphones. The original cost of the parts was $7, but we imagine the eBay auction exceeded that by a large amount.

If the name [Len Buckwalter] sounds familiar, he was quite prolific in magazines like Electronics Illustrated and also wrote several books about transistors. [Michael] also shows off his innovative coil winder made from plastic cups and a coat hanger.

We’d love to find some old kits like this, although, from one way of thinking, it is almost a shame to build them after all these years. With an added audio amplifier and fiddling with the cat whisker, it sounded just fine.

If you don’t like oatmeal, you could fire up the 3D printer. While the basic circuit is simple, you can make it more complex if you like.