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Wiimote Rubens Tube: Control Fire With Sound! (And a Nintendo Wiimote!)

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A Ruben's tube is essentially a demonstration of standing waves in air.



Numerous very small holes are drilled at lengths through the top of the tube and propane or a similar gas is fed through it. By forcing sound waves into the tube through a speaker at one end, varying areas of pressure are created. The higher flames occur at points of higher pressure (nodes) and smaller flames at lower pressure (antinodes).



I'll even show you how to control the sound with a Nintendo Wiimote so you can play god and control fire with gestures.



This is an easy physics experiment that might take a little time to assemble the parts, but the construction of which is straightforward with a fantastic reward!

REMEMBER!! Anytime you are dealing with fire, take the necessary safety precautions such as :
--Clearing the area of all flammable substances
--Using care when adjusting the propane valve
--Use ONLY in a well ventilated area
--If underage, operate ONLY under the supervision of a responsible adult

To help you remember, here's a safety haiku:

Danger! Hot Fire!
Keep Space Clear of Kids and Pets
Poor Burning Puppies


 
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Step 1: What the heck is this?

Picture of What the heck is this?
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A bit of history from Wikipedia:

"August Kundt, in 1866, demonstrated an acoustical standing wave by placing seeds of lycopodium or cork dust in a tube. When a sound was made in the tube, the material inside lined up in nodes and antinodes in line with the oscillation of the wave, creating a standing wave. Later that century, Behn showed that small flames could be used as sensitive indicators of pressure. Finally, in 1905, using these two important discoveries, Heinrich Rubens, whom this experiment is named after, took a 4-metre-long tube and drilled 200 small holes into it at 2 centimeter intervals, and filled it with a flammable gas. After lighting the gas (whose flames all rose to near-equal heights), he noted that a sound produced at one end of the tube would create a standing wave, equivalent to the wavelength of the sound being made."

In many basic physics classes the Ruben's tube is used as a demonstration of the relationship between frequency and wavelength. Students visually measure standing wave. Then, because the speed of sound in propane is 235 m/s, the students can calculate the frequency being played into the Ruben's tube. 

As the sine waves are played through the propane, they compress the propane in certain sections thereby increasing its density. This in turn increases the pressure, and because the area is at a high pressure (and air likes to flow from high to low pressure... thank you Le Chatelier) more air molecules are forced out these holes in an effort to reach equilibrium causing the flames rise higher. In areas where the propane is not as compressed, the area specific pressure is lower resulting in lower flame heights. Essentially when you are visualizing the wave with fire you are seeing a standing wave. 

Since we know that frequency (f) equals speed (v) divided by wavelength (lamba) we are able to quantitatively determine the frequencies running through the Rubens tube. (f=v/lambda) Now, when doing this, remember that "v" is not the velocity of sound in air, (roughly 344 m/s) but rather the velocity of sound in your gas ( in this case propane, so 235 m/s). Also keep in mind that elevation and temperature affect this, but 235 is a good estimate. So, measure your wavelength from peak to peak (flame maxima) or trough to trough (flame minima), plug into the equation, and you get your frequency.

After some digging at the college library, I was able to unearth the original journal publication by von Heinrich Rubens:

It was published on December, 8th 1904 in the Verhandlungen der Deutschen Physikalischen Gesellschaft- a German physics journal.  The original tube used was brass. It was four meters long, 8 centimeters wide, and had about 100 holes which were each about 2 mm wide. He used Coal Gas which was inserted on one end through a brass cap, and then covered the other end with a rubber diaphragm. Interestingly his sources of sound were bells, an organ pipe, or tuning forks.


jrapp11 year ago
Excellent article, and kudos on the great photos too, mate. Also check out this article that details the seriousness and danger involved with fixing propane regulator problems - I'm glad I did!
Yay for Blue Man Group!
namit2 years ago
We made this over last weekend for event coming up have few improvements to make but very nice.


Its 9 feet hight with 150 hold 2mm wide drilled ever 1.5mm in staleness steel.

For more videos and to see other revisions, http://www.tog.ie/

SpagoPizza2 years ago
It looks like the bellagio fountains at night :-)
sn0manX3 years ago
instead of pvc could i just use metal end caps, brass fittings, and whatnot?
(removed by author or community request)
why not? it seems more logical
budsiskos3 years ago
about what is the life of one of the propane cans when used for this?
RonnieJi3 years ago
What exactually is this for?
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Handy_Andy3 years ago
I don't know if it's been mentioned already, but I think you got the nodes and anti-nodes backwards in the intro (as far as i can remember from physics class last month). Nodes are low pressure points and anti-nodes are the points in between the nodes. Otherwise, nice Instructable. http://hyperphysics.phy-astr.gsu.edu/hbase/waves/funhar.html#c3
Blackross6 years ago
Instead of a straight pipe, would a curved tubing work? or square (might not with that one) but i was thinking about covering a good frequency range and coiling it and placing it into my fire place.
ScaryBunnyMan (author)  Blackross6 years ago
I had thought about this before and hadn't originally thought it would work thinking the effect was solely determinant of the cylindrical shape of the tube. However, in researching to find the original journal article written by Heinrich Rubens, I stumbled upon two articles written by Harold Daw. One was written in 1986 when he was at New Mexico State University and a follow up of the work they did on "Flame tables" in 1991. They were in different triangular, circular, or just square shapes. It was rather interesting reading. So in a concise and not drawn out explanation, yes.
that sort of research sounds fascinating. don't suppose you could do a link dump here, or pass on some recommended reading? I've recently decided to get into all of this wonderful Victorian era science.
cool, have you tried different size speakers, like a small simple headphone speaker? since all i've seen are ones that use larger speakers and vent tubing... although yours uses smaller tubing which is cool, but desktop speakers.
ScaryBunnyMan (author)  Blackross6 years ago
I had tried other speakers in the past, but really these desktop speakers can be too much for the tube. Those specific ones were choses because of their cost and great fit into the pvc cap. If I turn the volume on these up past even 1/2 the way, the flames get to large/distorted to produce a decent effect. Keep in mind that the original tube built by Heinrich Rubens only used tuning forks, bells, or organ pipes placed next to a rubber membrane on one end of the tube to drive sound waves. Good luck!
I may be interpretting you wrong, but it sounds like you're thinking that a longer tube will give you a greater frequency range, right? Actually, the frequency response is affected by the length of the tube, but not the frequency range per se, because it isn't a spectrograph, it's just showing the areas of constructive and destructive interference. So there is some fundamental frequency which is a function of the speed of sound in the devices environment and the length/shape of the tube. Then any harmonics of that frequency will also create pretty patterns on the tube. So a longer tube will show you more (higher frequency) harmonics. Perhaps that's what you mean by frequency range. If so, then disregard this comment, but just checking.
I wonder if the effect would be more grand if you were to use a 6" pipe 10' long with 1/8 " or maybe 3/16 " holes and a 6" 2-way speaker a propane tank from a grill with a larger supply line , and a electric igniter to remotely light the gas , with a electric soleniod valve to turn the gas on and off . any thoughts ?
ScaryBunnyMan (author)  stevens19886 years ago
In general, a larger diameter tube does seem to produce a greater effect. As it is now, only with a length of 4' or so, there is a slight unevenness in flame response close versus far from the speaker. The larger diameter seems to equalize that, and as long as you made the diameter sufficiently large, I'm sure 10' would look great . The problem therein lies in finding a speaker with the right diameter to fit the tube or otherwise building a funnel to adapt speaker size- I didn't have much luck with it but thats not to say others wouldn't. More gas flow unfortunately doesn't make it look better but rather worse. There's a 'sweet spot' so to speak when the flames are only maybe 1"-2.5" high... (for this size at least... with bigger tubes it's probably more). Once it's above that, the effect increasingly diminishes.
Chart from other Indstructable

the chart above from another instructable that was posted shows length versus frequency.... sorry just off from 10hr work day an not thinking right mind, but yeah what you said was what i was asking.
wocket3 years ago
so friggin cool!
yoyology3 years ago
Amazing Instructable.  Cool build, clear explanation, and well-researched background info.  Extra points for digging up Rubens' original work AND the haiku!

5 stars, my man.
jazzu6 years ago
Could you make a video with the music patched in directly to the tape? The echoy nature of the space you performed in kind of interfered with interpreting the effect of the music on the flames. Not that I'm complaining, it would just be very neat to see the effects with a proper soundtrack (kinda like the "Wizard of Winter" video with the christmas lights).


stukass jazzu4 years ago
now imagine that was ur neigbor, going to bed with that every night,  itll be cool for tghe firs five seconds
holy shamoley
 I love the safety haiku!
We really want to build this, but the pages that are linked for the wii are down. Any reccomendations?
Andrew105 years ago
whats better # Galvinized # Steel # PVC # Aluminium irrigation pipe to use for tubing
do not use pvc it will melt. galvanized will create a stinky chemical reaction do not use. aluminum is cheap but idk if it will work. steel works.
But aluminum does have the lowest melting temp (around 1200 degrees) and steels is in the 2,000's
ReCreate5 years ago
hmm,no video showing at least the flame...Add a video and also dont add it from youtube just an .avi file
Andrew105 years ago
Good experiment_ What is the dimensions you used for the tube...... And the material, from what I've seen and heard galvinized pipe should explode in this experiment. Can you please tell me what material you used???
lunasol3216 years ago
that was a lot of fun to build. thanks for the great instructable.
J_SCAP6 years ago
screw controlling fire i think you just invented the new electric instrument that requires body movement try hacking the wiimote and making it look diffrent and sell the thing and you will become rich
phenoptix6 years ago
Fantastic. I need a wii and a Ruben's tube for that matter!!
Try Golden Slumbers by the Beatles, Baba O Riley by the Who, or Sow by Red Hot Chile Peppers they all work really well with a Rubens Tube.
So I just got a prototype working with 1/2" copper pipe and a funnel design, I'm ganna expand on it a little more, but it works:

Rubens Tube vs. 1 (1).jpgRubens Tube vs. 1 (2).jpg
Just out of curiosity, is this something that you could indeed run for a long period of time without worries or are you limited to 5-10 minute durations?
ScaryBunnyMan (author)  AnimattersInc6 years ago
The original designs would heat up too much and melt the connecting pvc when other tube materials were used. With the aluminum irrigation pipe, siliconed in fittings however, I've run the tube for around 30 minutes before. It will heat up quite hot, but seems quite fine afterwards. I'm not sure if I would recommend extended durations, but I see no problem with it assuming you take the necessary precautions and/or use a different end cap than pvc.
Well, what fun that was. Here's what I did (and perhaps you can help me troubleshoot). My local hardware store only had a 1 7/8" galvanized pipe (and end pipe for chain link fencing) so that's what I was working with. The pipe is 6' 6" long and I left it at that length. Per instructions I started 6" from one end and went up to the 48" mark for a total of 81 holes. This left about 2 feet to the other end. I found a PVC sleeve that slipped over the ends of the pipe and on one side affixed a loose speaker the same diameter (just a touch larger actually) and the other end had the req'd reducers to the fuel line with a drilled out nozzle on the regulator. Inlet on 24" end / speaker on 6" end resulted in decent effect but nowhere near as pronounced. Inlet on 6" end / speaker on 24" end resulted in little to no effect. I suspect two things: One - the speaker not only may be too weak (especially when not enclosed in it's factory casing) but I believe the multimedia setup with subwoofer incorporates a crossover to limit the frequencies passed to the satellite speaker I used; and Two - perhaps my pipe diameter is too small or the excess on the end is too great. Any pointers? I'm close but still far somehow. My apologies if this is not the forum for this.... Thanks for a fun night in the workshop BTW.
ScaryBunnyMan (author)  AnimattersInc6 years ago
Sounds like you made a time of it! Pointers? Sure! A couple things to look for that I suspect may be giving you trouble: As a general rule of thumb, it seems that the longer the pipe, its diameter needs to increase a bit as well. If not, you get a "lopsided" effect where one end might respond too big and the other not at all. So I might try a shorter tube if you'll stick with that diameter. Also, what were you trying to play through it? Start with a simple sign wave to test as a lot of times the music can be too "busy" to give you an idea if it's working or not. When you light the tube without the sound on, can you get an even flame about 1-1.5" on all the holes? If not, start shooting for that. Most of the time when you can't get a good effect either you have TOO much gas going into the tube or the sound is up TOO high. You'll hit a "sweet spot" for your particular tube and materials at some point. Let me know how it goes and good luck!
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