Ever wanted to 'see' WiFi? With just an LED and a diode you can!

When I read this blog post I had to build one. I already had some red LEDs, but I had to buy the special diodes. When they arrived, I quickly soldered them together, making sure the white band on the diode is opposite the flat on the LED.

It worked really well. It's a very short range detector and will completely stop working if it's touching bare skin.

Orientation matters, It's effectively a dipole antenna. The length of the legs also matters, ideally each leg should be length a quarter wavelength AKA 31 mm. LED legs are different lengths, so they were removed, the diode legs were 28 mm, which was close enough.

After playing with it for a while, I wondered if the missing 3 mm was making a difference. I soldered on a bit of extra wire. I'm not sure if it made a difference, maybe it was a bit brighter.

Attaching it to the antenna of my router showed constant background traffic.

I also tested it around my microwave while it was running and found no signs of leakage, I didn't really expect to because it's fairly modern.

An idea I had when I first read the original articles was to make 8 of them and arrange them in a circle or star pattern so that the polarisation could be observed. Now that I can see how close the detector needs to be, I don't think it will work. Maybe I'll re-visit the idea in the future.