Patron Update: Chladni Plate

I think adding together multiple frequencies like a Fourier series is much more important than multiple sources

Tony B

like this, kind of? https://www.youtube.com/watch?v=f54aXn61MoE

Hi i’m pretty sure you will have to play with more then one vibration source

Also - If i dont mention that you seem to have gained weight - do i get a Keysight scope, or am i banned for life?

With only one sound (vibration) source, the resonnating standing waves will always be symmetrical around it. I am guessing that the pattern is being formed by salt gathering in the throughs of standing waves on such a plate. In order to get a 'vertical stripe' on an A4 kind of sheet i think you would need low frequency and high current, but you would get two of them, one on each side. Source: Hobbyist with no idea

Oh, it says Keep Calm and Make On! They gave it to me in some exhibition. I have a bunch of shirts like this I use as my comfy home clothing!

ElectroBOOM [Mehdi Sadaghdar]

Andy Kirby brings up a good point that may be expanded to acoustics. What about using two (or more) transducers (loud speakers) and adjust the frequency and phase of each such that you get a big trough whose position you could control by changing the phase of one of the speakers.

Ron Jones

what does your digi-key shirt say? and how do i get digikey to send me one?

> ... the vibration creates these patterns on the surface ... Okay, I'm with you. > ... without the help of gravity Now I'm afraid you've lost me... see this video for the reason I'm confused: https://www.youtube.com/watch?v=GBtHeR-hY9Y

Not *exactly* the same, but there is such a thing as an optical conveyor belt, in which two counter-propagating laser beams generate a standing wave pattern and trap particles at the minima/nodes (e.g. https://physicstoday.scitation.org/doi/full/10.1063/1.4797169 ). By changing the relative phase of the two beams, you change the position of the nodes. Doing this continuously is exactly equal to introducing a slight frequency difference in the sources. The underlying physics is remarkably similar to your setup. As an aside, I'd probably suggest using acoustic exciters to couple directly to the substrate (e.g. Dayton Audio) and I'd make the substrate large compared to the distance between the sources, to minimise the effects of edge reflections. Good luck!

I think you will need to find a sequence of frequencies that produce nodes in their standing waves at each position in the path you want the sand to follow. Of course each frequency will also produce nodes at various other positions, so you will have to look for a set of positions where the nodes at your path positions are not too close to other nodes, which would cause the sand to become scattered. In theory you could formulate some optimization criterion for this and calculate it, but this will probably be pretty complicated. As Andrew says, you could also just do it experimentally although this will take a lot of time and you will be finding sand everywhere for years to come!

Alexander Thomas

Or are you just trying to use constructive interference/standing wave to move them?

What I would do is map out the table into a grid. then define the path you want the particles to take. Test each frequency and record the movement of the particles in each grid along the desired pathway. Once you have recorded the movement associated with each frequency you can then create the correct frequency pattern needed to move the particles through the defined pathway. It will take a lot of resetting the sand, but if you record each test, you will not have to reset for each grid observation at least, but just each frequency.

:D oh right! Thanks! Should fix it in my real video!

ElectroBOOM [Mehdi Sadaghdar]

It can be done. I hope you figure it out! https://youtu.be/wYoxOJDrZzw?t=190

You mean Chladni Plate, right?

So Serious suggestion.. coat your class with a thin layer of wax, about 1/8th of an inch. If you make grooves in the wax that have an inclined angle / such that when you tilt the glass, one edge of each parallel groove is pitched slightly up, When the glass vibrates, the bits of sand/salt will bounce up from the groove it is on and be caught by the tip of the groove above it. It will help if the glass vibrates in a slightly circular motion rather than strictly up and down. The idea is to get the particles of sandsalt to act like the penguins on the penguin ladder toy toy, Also, instead of wax, 3d print a plane of perfect grooves :-) Video of the toy I'm talking about: https://www.youtube.com/watch?v=sYWGkFXQHO0 In an odd coincidence Kevin from Vsauce2 just used the toy to illustrate an idea on how you can win by playing 2 loosing games... https://www.youtube.com/watch?v=PpvboBJEozM

Lupo

Easy, set piece of glass at 45 degrees.

If you deviate slightly from the resonant frequency of the medium, you might see (apparent) slowly moving standing waves and nulls that can migrate the sand? I don't know how you got lines of sand like that on the plastic with the power source (speaker) at the bottom; some subharmonic of the sheet's resonant frequency?

I didn't even know the Chlandi effect was a thing until now so sadly I can't throw in any ideas

Zephy Foxy

There's a song and video (it's on utoob) "Cymatics" by a guy (scientist? musician? performance artist? Not sure) Nigel Stanford for some ideas (or look up that search term for other videos on the same subject.) Also check out "Automatica" if you think it would be cool to see a Kuka robot arm playing a bass guitar, drum kit, piano and turntables. Actually Mehdi if you could look at that one, would give me your opinion on how much of that would be possible without destroying the instruments (I mean in the early part)? I assume it was all sequenced in a DAW but it looks pretty synced and believable to me!

Jason Hoffman

Oh sweet new video~

Zephy Foxy

Seams impossible! The salt will fall off the plate! Maybe if you can prevent the sand from falling off the plate ? With silicone at the outer edges? With the right series of frequencies played in the right delay, you may be able to get the effect of movement :)

That's what I'm trying!

ElectroBOOM [Mehdi Sadaghdar]

Aha... moving sand and salt. Would be nice to see a chocolate ball on it. I am guessing that you will need 2 vibration sources...

Marcelo Henrique Gonçalves

Could you use two speakers, one on each side, with different frequencies? Maybe the particles will move from one to the other depending on what frequency you've set for both.

the answer is bitcoin :)

Seems impossible. At least Your eyebrows are moving many years but they're still on the same place.

Gimmie da met... oh, sorry - habit.

For the particals try French Chalk as it is ultra fine.