[HN Gopher] I built a light that reacts to radio waves [video]
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I built a light that reacts to radio waves [video]
https://rootkid.me/works/spectrum-slit
Author : codetheweb
Score : 437 points
Date : 2026-01-23 05:34 UTC (17 hours ago)
(HTM) web link (www.youtube.com)
(TXT) w3m dump (www.youtube.com)
| ebhn wrote:
| Very cool!
| segalord wrote:
| I love your poetry on a phone project so muchhhh
| milleramp wrote:
| Very cool, was there a conversion or look up table to convert db
| to gamma for more accurate human visualization?
| tzvc wrote:
| I'm not sure what you mean
| milleramp wrote:
| The db scale is logarithmic but doesn't match how our eyes
| sense light. So small changes in db may result in large
| visible light changes, or vise versa. Have you ever looked at
| a raw image, it doesn't look correct untill a gamma is
| applied, even though roughly the same information exists in
| both raw and gamma images. This is a similar concept. To do
| do this: db > linear > gamma This can be precomputed into a
| lookup table with the number of entries being the number of
| current steps, 8-bit 256 entries.
| mock-possum wrote:
| Incredibly cool. I was really hoping to see the more 'edge' cases
| - take the light out to the middle of nowhere, walk towards it
| and away from it with just your phone or a Bluetooth speaker, see
| it react to your approach. The bit at the end about it shifting
| over the course of the day is cool, but I wish the effect was
| more visually apparent - it mostly just looked like random noise
| the whole time to me.
| tzvc wrote:
| I wanted to take it war driving around paris and the
| countryside, maybe i'll make a separate short video for that
| dyauspitr wrote:
| This is fantastic. But the idea where you use a camera that can
| only see the wifi signals in the room like visible light is even
| more stunning. It would be even better if you could block out all
| light from the visible spectrum and only see the GHz band.
| shawn10067 wrote:
| This is such a neat project. The idea of translating invisible
| radio waves into visible light is mesmerizing -- it feels like
| giving your surroundings a new sensory dimension.
| mrtksn wrote:
| It's beautiful. I think I've seen something similar in a Ukraine
| war video where they use a device that lights up on specific
| frequencies that drones use.
| lucid-dev wrote:
| 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 intensity map like
| you have in the slit device..
|
| And then "look through the camera"... you would see a live three
| dimensional overlay of all signals within range (colored!)
| "interacting" with the antenna... but kind of more the "looking
| through the camera" sort of view, like you could "see" how those
| waves were interacting..
|
| And then wouldn't it be interesting to put a tin-foil hat to one
| side of the attennas.. and see how the waves change in real
| time... etc.!!!
|
| (I guess it takes three antennas, to triangulate the field? Maybe
| all three can still be mounted on a single device in close
| proximity?)
| mzhaase wrote:
| Yes it has been done:
| https://youtu.be/sXwDrcd1t-E?si=V75bEPMT8qGbo1wG
| diimdeep wrote:
| 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.
| phrotoma wrote:
| See also: https://youtu.be/o6WHhqDHSQ4
| janez2 wrote:
| your link has the "si=" tracking parameter in it
| johanvts wrote:
| If you buy three (or more) Phillips Hue bulps you can have them
| respond to motion detected by things moving around and
| disturbing the radio waves they use to communicate. So they
| must have pretty much the kind of map you want, but I dont know
| how easy it is to export it.
| ErroneousBosh wrote:
| > and you were able to (somehow?) from the antennas
| perspective, see the "direction" the frequency was coming
| from..
|
| You can kind of do that quite easily at low frequencies, by
| measuring the phase of signals coming in from a pair of
| aerials. If you put two aerials a quarter of a wavelength apart
| and switch between them very quickly at audio rate, then you'll
| get a tone when there's a difference in phase. If there's no
| tone the two signals are exactly in phase - the two aerials are
| exactly the same distance from the transmitter.
|
| If you look on some police cars you'll see a group of four
| aerials about 15cm apart stuck to the roof which used to be
| used for "Lojack" style trackers.
|
| There are a whole bunch of circuit diagrams floating around for
| doing this kind of thing, with the simplest being Ye Olde 555
| timer and a couple of PIN diodes!
| amelius wrote:
| This is sort of that idea with sound:
|
| https://www.youtube.com/watch?v=jL2JK0uJEbM
| mw67 wrote:
| Someone makes a kickstarter out of it please
| ggm wrote:
| I cannot find the YT video but an artist in residence did a short
| film with scratch-over of footage in an RF lab which tries to
| give a visual impression of the waves emitted by things present.
|
| We're bathed in EMF. It's what light is, but aside from that we
| use electricity so much now, we're in a sea of radiation in other
| frequencies too.
| cush wrote:
| The sounds were so cool -straight out of sci-fi movie.
| nickcw wrote:
| Traditional fix for coil hum is a blob of glue from a hot glue
| gun.
|
| It is fun making it part of the show though.
| cush wrote:
| His other projects are so interesting. I love this one
|
| https://rootkid.me/works/exhibit-a
| CrzyLngPwd wrote:
| Oh, that is fantastic.
|
| What would really finish it for me, though, is if, when the
| button is released, the device shows a website, with URL
| visible, with a photo of the criminal, with added facial
| recognition and lookup of social media to find their identity.
|
| What fun!
| simgt wrote:
| 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".
| abrookewood wrote:
| It's in teh description: "launching a fully functional
| darknet marketplace (http://spectretjag3wni6fzt445qwgokqlxnfz
| 7fxkicj5efxjywlinibm...) that offers a trove of illegal data
| for sale across borders"
| simgt wrote:
| > offers a trove of illegal data for sale
|
| I'm precisely asking for speculation on what this data
| could be, which is the goal of the artist as stated in his
| video
| pixl97 wrote:
| Stolen PII/identities/passwords are one of the most
| common you'll find.
| MPSimmons wrote:
| I don't need that, I already have a Twitter account
| louwrentius wrote:
| Let's call this what it really is: it's an _art_ project. It 's
| not 'just' a cool technical work.
|
| [0]: https://news.ycombinator.com/item?id=46729428
| amelius wrote:
| All those inductors... Isn't there a cheaper way to drive those
| lights, e.g. using DC voltage+pwm?
| seszett wrote:
| Those inductors are cheaper than what PCBWay charged for making
| that wooden box, I don't think their cost matters much here.
| tzvc wrote:
| Yes each LED channel has an inductor. I needed this because I
| wanted the LED to be constant current driven, to reduce flicker
| and improve their longevity
|
| (and they cost like 5ct each)
| 01100011 wrote:
| 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.
| saaaaaam wrote:
| That would still be cool - but what I really like about this is
| that it says something quite interesting about human existence,
| how we live, and in particular how we live in cities when we
| are in proximity to each other.
| Surac wrote:
| 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
| smellington wrote:
| Very appropriate soundtrack too:
|
| https://youtu.be/B_gLxVZuk60
|
| Uranium by Radioactiveman
| tzvc wrote:
| I had to dig deeep in my soundcloud to find it!
| TrackerFF wrote:
| 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.
| tzvc wrote:
| Yes, in the parisian apt. where I filmed the RF landscape is
| wild
|
| But tuning in to the specific wifi channel you router use you
| could even use this piece as a signal strenght plotter!
| ricardonunez wrote:
| That's what I was thinking, the project should yield a few
| different useful tools. That was a great video.
| pixl97 wrote:
| >use this piece as a signal strenght plotter
|
| Seems like it wouldn't be hard to filter this for something
| like the 2.4 or 5GHz range then put a different color
| filament at the demarcation point for each of the channels.
| fnands wrote:
| 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.
| alansaber wrote:
| I'm glad we can all agree this is really cool
| consumer451 wrote:
| Yeah, same here. Also, I can't recall a time since back when I
| used to make music that I got actually jealous of someone
| else's abilities, but here I am. :)
| pKropotkin wrote:
| Why do you need another source of irritation in your room?
| saaaaaam wrote:
| I don't think anyone is arguing that you NEED this. But it's
| the intersection of technology and art, and says something
| about the way we live. You can view it as nothing more than an
| irritation, but I think that's a shame.
| bethekidyouwant wrote:
| Are you asking why he needs another light? His project doesn't
| make radio waves.
| tzvc wrote:
| Creator here, thanks for posting. And feel free to ask me
| anything!
| xtoilette wrote:
| I love your works, what kind of background do you have?
| tzvc wrote:
| CS background, but I've always been a "bricoleur" on the side
| flexagoon wrote:
| Love your channel! Do you have any plans to eventually open
| source your projects? (Both in terms of hardware and software)
| mechazawa wrote:
| I'm personally especially interested in 'Latent Reflection'.
| I've tried to make something similar never got to a point
| where I was happy with the output the AI model gave me.
| tzvc wrote:
| Lots of tuning to get the model to not immediatly spiral
| into nonsense. But small models are getting better by the
| minute, maybe i'll revisit it with a better model and share
| all the code
| tzvc wrote:
| To be honest, all of the hardware and software is really
| poorly documented. But I guess i coudl still publish it as is
| flexagoon wrote:
| Yes, would be still great! I'm sure a lot of people would
| have fun playing around with it even without the
| documentation
| cheschire wrote:
| Do you have a list you would be willing to share of trusted
| manufacturers & suppliers that you reference for different
| products or materials?
| flexagoon wrote:
| At least in the last video it seems like he used both PCBWay
| and JLCPCB for manufacturing
| cheschire wrote:
| Yep! The choice of JLCPCB after having used PCBWay is what
| inspired the question.
| tzvc wrote:
| I used JLCPCB for the pcb cause they integrate well with the
| pcb design software i use (kicad or easypcb)
|
| And I used pcbway for the sheet metal fabrication
|
| Honestly they are both great and similarly priced
| jenowigner wrote:
| amazing project ! well done ! inspiring to see it this morning
| the youtube algo recommended it for me. I was thinking what
| would be a budget way of creating this ? maybe a $20 SDR
| instead of the hack rf , seems to be a waste of the hack rf to
| use it as a lamp :)) I think the way you did must have cost you
| over $1k. Thanks for the inspiration !
| orbsa wrote:
| IIRC, a regular SDR dongle will not be able to process the
| full bandwidth of GHZ range.
| pixl97 wrote:
| I do think most people implementing something like this,
| especially in the exact way this one was implemented would
| really just be interested in the Wi-Fi ranges.
|
| When I was doing wireless stuff we'd show customers the
| output of RF analysers to show that even with their wifi
| turned off their spectrum was packed full of noise.
|
| Having a large viceral display of this would quickly
| enlighten them.
| tzvc wrote:
| Hackrf is defo overkill for this. I got it cause my initial
| plan was to cover the whole spectrum
|
| You could probably do it with a cheaper SDR, but it would be
| slower
|
| Total budget for this is around $1k
| 1e1a wrote:
| The $5 nrf52840 should be sufficient, it can scan 114
| channels (from 2400-2514 MHz) several times per second,
| measuring the approximate RSSI.
| bethekidyouwant wrote:
| You could not use that as an SDR to make a waterfall which
| is required in this case
| direwolf20 wrote:
| HackRF isn't a good SDR by any metric except for the date it
| came out.
| ipdashc wrote:
| What would a better alternative be?
| proee wrote:
| How much did that sheet metal frame cost you from PCBWay?
| Thanks for sharing.
| tzvc wrote:
| Around $200 delivered to france
| dangoodmanUT wrote:
| You're very good, I'm jealous of your work
| djhworld wrote:
| Awesome project & video, thanks for making it
|
| Where did you learn all the PCB design stuff to make your
| circuit boards that controlled the filaments?
| thinkingtoilet wrote:
| Very cool project. Thank you for sharing. It's rare where
| something so technical can have such an artistic manifestation.
| Well done.
| steeve wrote:
| very very cool !
| sergioisidoro wrote:
| I just watched all the other videos of their pieces, and all of
| them are absolutely amazing conceptual explorations of our
| relationship with technology. Really amazing stuff
| SiempreViernes wrote:
| The bit in the phone project where he cuts out the poem authors
| intro seems a bit scummy though, all that work he's _making_
| uncredited... then he finishes the video by showing _him_
| signing the piece.
|
| I guess it's a good commentary on how tech people value other
| peoples work.
| fanatic2pope wrote:
| Indeed, and the final result isn't particularly good as an
| art piece.
| curiousgal wrote:
| I wasn't surprised by that, I studied in one of the best
| schools in France and that attitude was prevalent amongst
| students.
| sush1612 wrote:
| you have everything right in front of your eyes, next if you add
| a transformer which convers these light signals into what they
| actually are then Voila, you can see what's travelling in the air
| (Photos, conversations, music)
| levidos wrote:
| Except it's encrypted with TLS
| sush1612 wrote:
| not far away
| asgerhb wrote:
| Sawing the first shot, I thought the LED candle on the coffee
| table was the device. That would have also been cool, having
| flickering affected not by wind, as with real candles, but by
| radio waves.
| kh_hk wrote:
| Cool project. Here's some OT: where do people learn to make these
| videos? Fast paced but calm narration with chill music and sped
| up action mixed with regular speed. It's a matter of consuming a
| lot of this content until the form clicks, or you need to go to
| influ-school?
| xtiansimon wrote:
| Yo. You have to make videos. Then, seeing videos that you like,
| you secretly try to "steal" those ideas you articulated.
|
| Just don't tell anybody you're a copy-cat.
| wpietri wrote:
| "Good artists borrow. Great artists steal." -- me
| tzvc wrote:
| No influencer school, no video experience whatsoever actually
|
| I watched TONs of youtube videos growing up and I guess I took
| inspiration from what I liked in each: fast pace, always shows
| what you are talking about on screen (no talking head), include
| tiny projects in the main one, explain the science, use an
| intro to captivate and an outro to nail the point, use music to
| drive rythme
|
| I film and record audio with just my phone
| kh_hk wrote:
| Thanks! That kind of makes sense. It's always interesting to
| me when I see patterns that make videos work well, and I
| usually have a lot of questions about the production.
|
| Another question that I hope is not disrespectful: does
| PCBWay and JLCPCB pay for brand placement during the video or
| was it just a tribute from your side?
| dangoodmanUT wrote:
| Man iphones have come a long way
| pixl97 wrote:
| My wife has worked in marketing for years and setting up
| photo shoots/video shoots has changed massively. A huge
| amount of the video and pictures that don't require a
| specialized lense are just done with feature phones these
| days.
| relaxing wrote:
| Remember the days when you could just _make art_ , without having
| to be a Content Creator?
|
| Respect to the artist, I know I couldn't do it.
| pixl97 wrote:
| You can still make art without being a content creator. I would
| assume with the accessibility to both knowledge and products
| more people than ever are.
|
| With this said, if they are not content creators, you'll never
| know about them. That's not any different than the past were
| art was typically only known to those with in viewing range of
| said art.
| Mouvelie wrote:
| What an excellent video.
|
| Depsite visiting Hackernews multiple times a day, I am not a tech
| person. Seeing people creating such thing in a way I can
| undestand (which is maybe...10-15 % of the posts here ?) is so
| refreshing !
|
| The editing is sharp, the setup looks so cool and the channel !
|
| Thank you for making this !
| halfmatthalfcat wrote:
| Looks like Circuit Python is used?
| dwa3592 wrote:
| very very impressive.
| pringularity wrote:
| The lights sort of did this already on accident, but making a
| more robust audio-output version of this would be fascinating as
| well.
| m3kw9 wrote:
| would look good if he put a heavily frosted material infront.
| Right now is gonna cause more headaches than a 5g transmitter in
| your room
| SilentM68 wrote:
| That's a great design and idea. Have you considered designing a
| light-based Morse code device? The light would be invisible to
| the naked eye, requiring special glasses/detector to translate
| either mechanically or digitally. The source light (e.g. neon,
| lamps, something new) would be encoded with encrypted messages,
| so it doesn't look like obvious Morse code by using aspects of
| steganography where encrypted data would be hidden in pseudo-
| random light intensity/pulse patterns mimicking candle flicker,
| noise, etc.). It would require a custom protocol, error
| correction, obfuscation. All made on the cheap.
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