Instructables
Picture of Mechanical Wave Driver for Chladni Plate
I volunteered to help a friends child with her science fair which we decided to do on sound. After seeing the chladni plate displays on YouTube I thought this would be a great display for the project. I assumed you could drive the plate with just a simple speaker but the lower frequences just bounced the salt right off while the higher had to be unbearable loud to even get the salt to move. Overall a regular speaker produced limited results for the loudness you had to deal with.
A lot of people use a piezo but I found this to be to small to produce a good effect. I ran across a website Cymatics which had a link to a wave driver you could buy and after looking it over I realized it was just a modified speaker which could be easily made for cheap. This is my first instructable.
 
Remove these adsRemove these ads by Signing Up

Step 1: Materials and tools and Misc

Materials I used:
A discarded 8" speaker with its coil intact
small sink strainer
cardboard (an old cereal box)
heavy canvas (optional)
8-32 X 6" threaded rod (1)
3/8 X .171 X 1 Nylon spacer (1)
1/4" plexiglass
8-32 Insert Lock Nuts (4)
Standoffs (4)
Metals spacers (4)
8-32 screws (8)
9 1/2" X 9 1/2" metal plate (cut from old VCR casing)

Tools:
Safety Goggles
Gloves
Nut driver
Wrench
Vise-Grips
Hot-glue Gun
Razor Blade
Scissors
Sabre Saw with Sheet Metal Blade

WARNING
This project involves cutting metal and plexiglass with a sabre saw, which can be dangerous.
Plexiglass is not easy to work with at this thickness. It cracks, shatters, and melts. You might want to use wood or metal instead of plexiglass.
amyasdfghjkl6 months ago

Do I have to use the nylon spacer? And could I use a thinner plexi-glass?

Alekxos1 year ago
I tried building this configuration for a high school physics project. The design works well, but after about 20-30 seconds of repetitive motion, the wave driver's magnetic coil stops working. The failure usually occurs at a frequency around 300Hz, even on low amplitudes. The first speaker produced a strong smell of burning metal when it burned out around 900Hz. So far, I have burned out three speakers. What am I doing wrong, and is there any way to ensure that this does not happen again if I build another one?

Thanks,
Alekxos
Misac-kun Alekxos9 months ago

You probably put too much weight on the voice coil. A lighter build should solve the problem, like a lighter metal plate or a lighter rod.

Great instructable! Has helped me out a ton! Im looking to get a wide range of patterns from different frequencies, what size speaker would you recommend to bet the broadest range? also can you suggest an amp wattage for this too? Thanks!!!
gabstar6 years ago
if i have a new speaker... do i still need to cut everything and leave it like this? Sorry if the question is stupid.... but i need to ask....
Nope, you don't !
http://www.instructables.com/id/How-to-make-a-Chladi-plate-vibrating-membrane/
I made this instructables just for that purpose : You can make a vibrating MEMBRANE (not a plate) so you don't need to destroy your speaker, and you can use a less powerful speaker and amplifier. You will get Chladni figures at lower frequencies and you can always re-use your nice new speaker later on :)
mathiastang3 years ago
Would it be possible to connect something like a digital drumpad?
pocketspy4 years ago
So I made one of these, and using a frequency generator I got from work, I decided to do some experimenting on different materials. I got some from a local creek that is known for it's gold. It took me awhile, but I can now separate the gold dust from the normal sand. I held a magnet over the plate to remove any iron particles. After two days of playing around I managed to get maybe a tenth of an ounce out of 5lbs of sand. But it works.
matthewvenn4 years ago
 nice instructable thanks, I just made my own nice and quick!
papacito235 years ago
Where I can find the generator of functions?
In my AlgebraII (2) class, we have quite a number of functions generated for our disposal. Isn't being in an advanced math class great?
kmpres5 years ago
Nice instructible.  Kinda wish I'd thought of it when I was in school. 

FYI, re-entering Edit mode and briefly accessing each step would restore the formatting in your text. This has happened to me a few times.
stasterisk6 years ago
Here's a way easier/more fun way to do the demonstration:


 yeah ive done the same thing but its quieter and if you can have it just as loud from your computer or something you should play a sine wave between 120 hertz and 60 hertz nice job i used crusted powder instead and its the same was that your kid sining along lol cool
Azraelsrebellion (author)  stasterisk6 years ago
Thank you for the comment but this hardly the same thing! Chladni Plates work by the plate resonating at different frequencies setting up the standing waves which produce the patterns in the sand or salt. This video appears to be cornstarch and water on top of a normal speaker protected by saran wrap. This will never produce the same effect.
could you use a subwoofer speaker for this? instead of a big regular speaker?
 it might work but wouldn't be effective as subs are meant for low frequencies so it might be better with a regular speaker
bob_dobbs5 years ago
Thank you for posting this! This looks like an excellent project. It seems like the best alternative to buying a wave driver. I am in the process of acquiring the necessary materials for the project, however i was unable to buy all the necessary materials because i need the specific measurements of the parts ( i was able to find the threaded rod, insert lock nuts, sink strainer, and nylon spacer). I would be most sincerely appreciative if you could please provide the specifics for the materials used. Thank you. Best regards.
pocketspy5 years ago
My question is, if you can find the proper freq. for gold to vibrate into the center of a circular plate, would it be possible to build a chladni device to separate gold dust from the soil it is in? I was thinking of building a portable device that could save me alot of time instead of panning. Someone let me know if this sounds plausible.
Actually use a magnet to remove all the magnetic materials from the gold, such as iron, copper, etc. Oh and if you do that, put a piece of paper or something between the magnet and the dust, or that pesky metal dust will be hugging your magnet forever! (Gold isn't magnetic so it won't be attracted to the magnet)
alessiof765 years ago
I also wanted to do this project but you were faster and more talented than I! nice work!
evga5 years ago
How is the speaker powered and what are the alligator clips connected to. I plan to use an amplifier and a notebook computer using a software called tTone Generator 4.0 Thanks in Advanced
maiyahi16 years ago
thank you for the instructions. I saw a youtube video too and thought I would make one. but I didn't know how until I found this. its for my science fair. I just want to know what the plexiglass for? I didn't use it but it still worked OK. it didn't look as nice as your but it still worked. just wondering.
Azraelsrebellion (author)  maiyahi16 years ago
The plexiglass was used as a support for the rod to pass through. It helps stabilize the top plate but should not prevent the rod from vibrating freely.
i'm doing this for my schools science fair and ive run into some problems 1. my image isnt coming out right. is it because my metal isnt flat enough? is my aluminum thick enough? is it because i didnt support the central beam? 2. its too loud. if i cut away the fabric of the speaker will that muffle it? what if i just cover the speaker in foam?
Azraelsrebellion (author)  psychofish256 years ago
1. Your metal isn't flat? How thick is your aluminum? Not supporting the central beam may cause problems if your plate is not centered on the beam causing an imbalance which may set off irregular vibrations. 2. Yes cutting away the paper inside the speaker will take away most of the sound and this is most likely what is causing the problem. The plate is being vibrated at more than one place by the sound waves coming off the cone then bouncing of the plate. Vibration at one point on the plate is crucial to the shapes being formed.
rickharris7 years ago
Hi, When we cut acrylic at school (plexiglass) we put a strip of masking tape on the top surface and mark the cutting line on that - When you cut through the masking tape for some reason the acrylic will not melt back together - and this is with a thin fret saw blade.
well, when you cut acrylic and it melts, you're doing something wrong anyway, either the blade is the wrong type or it's going too fast... or both.
crapflinger7 years ago
that's pretty nifty but...how much did the child DO...and how much did they think of?
Yeah, looks cool, and its a good instructable, but when i was little i always hated the kids whose parents did all the work for them at a science fair. And you can ALWAYS tell. This one won't we hard to recognize as an adult-made project. I'd like to know if the child was involved in the research you say you did. this would have been a perfect learning opportunity.
Azraelsrebellion (author)  Andrew5467 years ago
Well yes we have thought of that. The fact that I made the wave driver will be posted on her backboard as per the rules of the science fair. She is being taught how to use the device along with the basic idea behind why it works. She will be the one running the function generator that day to bring up the different patterns. She will still be doing her own report and learning the material to give answers to the judges. That is the most important part really. This is only a third grade project so a parent/ friend participation is expected and the idea is to get kids interested for the more challenging science fairs in the years to come. At this age parents should be helping out more with the project to help spurn more of an interest in science. I guess we could have gone with the old two can telephone routine (we probably will have one sitting there anyway which she has made.) But I wanted something that would keep her interested in the project as well as the judges :)
bah..i typed up some long stuff and it didnt post.. i'm not trying to insinuate cheating...i'm sure with a project of this scale that you're teaching the child alot...i'm glad to see that she will be doing the report and research etc...i think my main questions where: did she actually help with any of the construction process? maybe a little wiring or sanding? and who came up with the idea? i may be biased on the parental help deal in science fairs (i know it's expected)...probably because in third grade i made an AWESOME steam engine from scrap parts my grandpa had in his shop and wrote a 12-13 page report about the history of steam power and the mechanics behind it etc.. only to get second place to some rich kid who's parents did his entire project...from the displa (a crappy diarama of a nuclear power plant) to the 4 page report that was written to look like a 3rd grader wrote it
HamO7 years ago
Excellent instructable, great pix. Well done. Thanks for sharing.
Yeah man, Wild!
That's pretty darned cool.