I built a light that reacts to radio waves [video] • Hacker News Board

Re: I built a light that reacts to radio waves [video]

#21

Post by simgt » Fri, Jan 23, 2026, 8:53 AM UTC

cush wrote: post #13

His other projects are so interesting. I love this one https://rootkid.me/works/exhibit-a

The narration is very nice. Any idea of what the data could be? He mentions that it's legal for him to store but illegal to sell abroad and ranges from "bad to very bad".

Re: I built a light that reacts to radio waves [video]

#22

Post by 01100011 » Fri, Jan 23, 2026, 8:54 AM UTC

A much simpler and less cool project would be to convert a slice of the RF spectrum into an RGB value with lowest frequencies mapped to red, highest to blue, and the resulting color being how we would perceive the mix.

Re: I built a light that reacts to radio waves [video]

#23

Post by Surac » Fri, Jan 23, 2026, 9:01 AM UTC

I once had a antenna with a lamp on it. It was used to detect best place for the radio. It just rectified the energy it received and used a very tiny light bulb

Re: I built a light that reacts to radio waves [video]

#24

Post by smellington » Fri, Jan 23, 2026, 9:08 AM UTC

Very appropriate soundtrack too:

https://youtu.be/B_gLxVZuk60

Uranium by Radioactiveman

Re: I built a light that reacts to radio waves [video]

#25

Post by amelius » Fri, Jan 23, 2026, 9:21 AM UTC

lucid-dev wrote: post #9

FANTASTIC!! I was just thinking about this the other day, and wondering about directionality... For example, if you had a camera facing a space, and the receiving antenna was within that space... and you were able to (somehow?) from the antennas perspective, see the "direction" the frequency was coming from.. And then map the different specific frequencies within the desired bandwidth to colors... and of course inten…

This is sort of that idea with sound:

https://www.youtube.com/watch?v=jL2JK0uJEbM

Re: I built a light that reacts to radio waves [video]

#26

Post by diimdeep » Fri, Jan 23, 2026, 9:47 AM UTC

mzhaase wrote: post #14

lucid-dev wrote: post #9

FANTASTIC!! I was just thinking about this the other day, and wondering about directionality... For example, if you had a camera facing a space, and the receiving antenna was within that space... and you were able to (somehow?) from the antennas perspective, see the "direction" the frequency was coming from.. And then map the different specific frequencies within the desired bandwidth to colors... and of course inten…

Yes it has been done: https://youtu.be/sXwDrcd1t-E?si=V75bEPMT8qGbo1wG

The title is: This ESP32 Antenna Array Can See WiFi

And every time I see something like this I like to remind to myself and imagine what spherical grid of Starlink satellites linked by laser is really capable of instead of mere internet as it is advertised.

Re: I built a light that reacts to radio waves [video]

#27

Post by TrackerFF » Fri, Jan 23, 2026, 9:50 AM UTC

Cool project. I was going to say, the end resulting light should be a pretty saturated spectrum, given that many RF sources just keep pumping out waves, and the those waves propagating and bouncing around.

I think one fun application would be a light which represents your wi-fi strength around the house. Obviously in a smaller apartment that's really not a problem, but in larger houses it would be fun to see.

Another application would be to find hidden RF sources / leaks. I have a home recording studio, and for the life I could not find some RF source that kept adding noise / interference. I could roughly detect the frequency of the noise, but not its origin. I guess if I had a couple of RF sensors I could try to triangulate my way to it.

Re: I built a light that reacts to radio waves [video]

#28

Post by seszett » Fri, Jan 23, 2026, 9:54 AM UTC

amelius wrote: post #20

All those inductors... Isn't there a cheaper way to drive those lights, e.g. using DC voltage+pwm?

Those inductors are cheaper than what PCBWay charged for making that wooden box, I don't think their cost matters much here.

Re: I built a light that reacts to radio waves [video]

#29

Post by fnands » Fri, Jan 23, 2026, 10:11 AM UTC

Very cool! I was having a conversation with my colleagues yesterday about building something to detect when you get scanned by a SAR (synthetic aperture radar) satellite (we're in earth observation), but you'd have to get a directional antenna to not be drowned out by terrestrial radio signals.

Re: I built a light that reacts to radio waves [video]

#30

Post by phrotoma » Fri, Jan 23, 2026, 10:17 AM UTC

mzhaase wrote: post #14

lucid-dev wrote: post #9

FANTASTIC!! I was just thinking about this the other day, and wondering about directionality... For example, if you had a camera facing a space, and the receiving antenna was within that space... and you were able to (somehow?) from the antennas perspective, see the "direction" the frequency was coming from.. And then map the different specific frequencies within the desired bandwidth to colors... and of course inten…

Yes it has been done: https://youtu.be/sXwDrcd1t-E?si=V75bEPMT8qGbo1wG