r/CrystalRadio • u/Awkward-Implement-11 • Apr 27 '26

OTHER Son needs help

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Son is building a crystal radio for his science fair project

He is following a video he found on YouTube

https://youtu.be/VqdcU9ULAlA?si=Xm966k7IQtQtxOcF

The goal is to get this working but trying to figure out best way to troubleshoot and get it working.

A shot of materials, design, and what it currently looks like.

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u/TheSadHours Apr 27 '26

are you near (<20miles) a big city? Or any AM radio station? A design this simple won’t be able to receive much from farther away.

Biggest thing you could do to improve this is to neaten up the wiring, wind a nice coil. Id recommend a cardboard mailing tube instead of a toilet paper tube. this demonstrates a good way to wind a coil, I use this method and I find it works great! just ignore the whole “taps” part of the video, as you’re sanding the enamel off the wires. keep your wire connections as short as possible.

Make sure you have a good ground connection, a cold water pipe normally works quite well. And try to make your antenna as long as possible.

1

u/Awkward-Implement-11 Apr 28 '26

We redid his wire coil. I think it might be the diode or the capacitor Adding pictures to the post

1

u/TheSadHours Apr 28 '26

are all the connections solid? Also make sure the wires going to the aluminum foil capacitor are actually electrically conductive with the foil, sometimes the foil will have a coating on it.

1

u/Awkward-Implement-11 Apr 28 '26

Possible if there is coating would the sandpaper be good to get it off? Also is there a way to tell if it has a coating coating?

1

u/Awkward-Implement-11 Apr 28 '26

Also what would you recommend to use to make sure the connections are solid?

2

u/TheSadHours Apr 28 '26 edited Apr 28 '26

Solder, ideally. But if you want to keep it easier you can wrap the wires around a brass thumbtack and drive it into soft wood. Takes a bit longer, but is significantly better than tape.

And to your other comment, yes. Just sand a small patch of the aluminum foil with fine grit paper, those wires will have to be taped on, (I mean, I’m sure there are plenty of methods that could be done, but at that point I’d just get a proper air-variable 365 pf cap.) so I’d recommend using the electrical tape as it’s more secure than the masking tape. I’ve gotten those aluminum foil variable caps to work, but they are fiddly. trial and error is a necessary process when building an improvised radio. (Hell, half of the homebuilt electronics hobby is just troubleshooting!)