How Lo-Tek Can You Get?

Here are some pieces of Galena and Pyrite. Both can be used as detectors in crystal radio sets. These pieces were bought at rock shops, but both minerals are common rock-hound finds in the Northeast and elsewhere, as shown on the maps to the right. What we have here are the first makings of a radio receiver that you could literally make with local rocks dug out of the ground. If you visit https://www.minedat.org you can search to see if Galena, Pyrite, or any other mineral is/was found in your area.

This is an old variable capacitor which I think was salvaged out of a junked antique radio. I’m not sure because the construction is simple enough for me to think that it might have been homemade. It was made by sandwiching a square of plastic insulating material between two metal plates. The capacitance of the device varies with the distance between the plates. It’s another swap-meet find from one of the many junk boxes you find under seller tables. That’s where the good, cheap stuff is. While usable as is, it also serves as a good example template for when you want to roll your own components for simpler radio experimentation. Yes, such a thing is possible.

This is one of the late Dave Wildflower’s home-brew crystal sets. The detector is a piece of Galena set in a copper pipe cap. The tuning capacitor and coil are all home-brew. He used a Radio Shack Amplified Speaker for the audio. You can watch the radio in action at https://youtu.be/B_OYORo4-tA?si=uCfqLWiOkQvSN2p1.

Wildflower found a lot of info on building crystal sets on the Internet. One of his favorites was The Boy’s Book of Crystal Sets which you can download a PDF at https://www.worldradiohistory.com/UK/Bernards-And-Babani/Bernards/126-Boys-Book-of-Crystal-Sets-v12.pdf. This one is small and worthwhile enough print out. There is one that’s even better though, but you’re gonna have to go and buy a copy online.

The absolute must-have book for primitive radio experimenters is H.P. Friedrichs’ Voice Of The Crystal – How To Build Working Radio Receiver Components Entirely From Scratch. This book will show you how to build a working crystal radio receiver from junk parks you can find anywhere. Friedrichs’ web site is one you need to visit. There is a wealth of information on there. This copy of the Engineer’s Mini-Notebook – Communications Projects has seen some things, but it’s one of the less common ones that you’ll find in the wild. I discovered this one in the bottom of a junk box at a swap meet with a few other piece parts. While not as stone tools and bare hands in project content as Voice Of The Crystal, it has a lot of simple, functional projects that use common discrete components.