seeing sound and breaking wine glasses - wine glass
This project is driven by a video I saw on YouTube that seems to show the waves that guitar strings appear when they are playing (see video).
I know it's a "scroll shutter" effect, so I want to see what's actually going on when I'm playing guitar strings.
I don't have expensive high speed cameras, so I cheated and made the flash with some spare parts I placed.
Although the guitar strings are quite not in
Interestingly, other objects also vibrate, which is called resonance.
All the materials resonate, and some are quite notable.
Wine glasses are known for resonating and we can break one with speakers and some simple analysis.
The best part is that we can see the standing waves formed by the edge of the glass with the flash we are going to build.
The Libo "scroll shutter" effect is an explanation of the waves in the guitar strings we see in many of these videos.
This effect is the result of how the camera forms each frame, that is, by scanning the data in the frame instead of capturing all the data at once.
If the vibration frequency does not match (329hz)
Capture frequency (30hz)
The frame will "draw" a standing wave.
In fact, guitar strings mainly vibrate in their basic mode.
That is to say, there is a standing wave with a half-wavelength, or a simple motion up and down.
Think about the rubber band that was pulled out
The integer times of this basic frequency exist at other frequencies.
For example, for low E (82Hz)
We also have: 2*82 = 164Hz3*82 = 246Hz. . .
EtcHowever, their contribution is very small compared to the fundamentals.
If we reduce the tension on the string to a high degree of damping in the low-frequency mode, we can start to see the outside sound of the string.
This can be achieved by tying one end of the rope to the speaker and slowly carefully lowering the tension.
The idea of a flash is to use periodic motion to illuminate only certain points in the cycle of these scenes.
At frequencies above 60 hz, most people do not see the flashing of the flash, and our brain tells us that there is only one continuous light source.
The camera flashes or generates scanned artifacts because they sometimes capture dark frames that, unlike our brains, do not merge into continuous images.
If we light it only at the resonant frequency of the vibrating string, then we will see a wave fixed in space that does not move.
If we illuminate at twice the resonance frequency, we will see waves fixed in space with positive and negative amplitude (
As shown in the photo).
If you hold a speaker, play a tone, and match the strobography frequency, the speaker head will not move.
If you just offset the strobography frequency a little by 1 or 2Hz then you will see the motion but it is slow.
This is because the speaker is now illuminated with a motion offset of 1Hz.
Therefore, the position of the speaker is slightly different each time the light is turned on.
Objective: to illuminate a very short scene at a fixed time interval.
The hardware build flash is a relatively simple task, and I have attached a schematic diagram that conveys the overall idea.
You want bright LEDs and good power supply.
I am driving 3 w White led in a series of N-led series
Channel mosfet rated for these current.
Note: Please ignore the name of the component in the schematic.
The Mosfet is 2SK4017.
These are the 3 w LEDs I use.
For this project, I connect all MOSFET gate terminals to a single pin on the Arduino.
The Arduino I use is Leonardo, but any Arduino can work for this project.
I drive my led at a speed of 12 V to be 3 Conservative.
6 ohm 3 w resistor in series.
Tip: If the LEDs are pulsed in a very short period of time, it can handle a much higher voltage than the rating.
Be careful though, as my code changes the pulse duration to a fraction of the delay time.
For a long delay, the time on time can be 10 ms.
The software can complete the frequency pulse part without doing anything special.
In the code, I do the software pulse-
Width modulation (PWM).
The only thing that's special is that I switch between delayMicroseconds ()and delay()
Depending on the frequency of the request.
Become unreliable for large values (10-15ms).
There are more accurate ways to accomplish this task, especially if you have other things you want Arduino to do or want to work at a very high frequency.
The longer the flash is turned on, the more cycles we capture, the more blurry our eyes are.
Therefore, we hope that the time is very short.
The problem here is that this is actually equivalent to a duty cycle.
Therefore, the dimmer and dimmer appear in our strobe lights, the smaller the value is.
I used 10-
20%, good effect.
But, without sacrificing the overall brightness, the smaller the value you can get, the better.
One of the cool things we can do with a flash is to see the resonance in the material, a classic example is a singing wine glass.
We may have all shown the opposite.
At a party at some point, wet our fingers and make our wine glasses hate social behavior.
This is because the glass converts the input energy, such as the vibration of our fingers, into its own vibration, and the frequency is called the resonance frequency.
If we record the sound of the song, we can find the exact tone and induce the vibration by playing back.
The easiest way to find the tone is to go online and find a frequency generator like this, play the tone until you find something on the pitch, and then, before you think you 've dialed it, change the tone carefully.
The most accurate way to find the tone is to record the song and perform a Fourier analysis.
I won't go into details here, but a quick search in google will find some ways to do this.
I brought the data into MATLAB and did it directly, but I believe a lot of audio programs will do this analysis standard as well.
There are some web tools to get you into the pitch, but I can't find the one I really like.
This Fourier Analysis Network tool will allow you to get into ballparkIn in any situation, and you can check your work by setting the flash to this frequency and having the glass sing.
If the frequency is close, you can see the edge of the glass moving.
The slower it moves, the closer you get to the tone.
Play back the tone and break the glassI drill a 1 "hole in a piece of 0. 25"-
Thick wood used as a wave-guide.
It is firmly tied to the front of my speaker and the holes are directly concentrated on the head of the speaker.
This helps ensure that sound waves do not interfere with the induced vibration in the wine glass, but it is not entirely necessary.
Keep the wine glass as close as possible to this hole/speaker without touching the wine glass.
Now play the tone at medium volume.
Put a straw or a folded piece of paper on the wine glass.
You will see the biggest vibration of paper.
Strong when the tone matches perfectly.
Make sure your flash matches this frequency or deviate slightly from this frequency.
When you increase the volume, you should be able to see sharp bending inside and outside the wine glass.
When you continue to increase the volume, the glass will eventually break.
Wear safety glasses and protect your ears!
The speaker I use is a small bookshelf speaker with a 25 w amplifier.
The wine glass is broken in about 75% volume.
If you have a problem, first verify that the tone is correct.
You need to dial in with 0.
1Hz is required for this job.
Next, try to create a wave catheter as described above.
You can also try to surround the glass with pillows or other soft materials.
You don't want the sound to echo, and you don't want it to be undisturbed.
Finally, experiment with different wine glasses. Very thin-
The wall works best.
There are some defects in the glass, which can also cause damage.
Go and try your flash and see what other periodic movements you can isolate.
I experimented with drops of water on my speakers in the video and got some very interesting results.
Others try to memorize some behavior in different ways.
Post and comment with suggestions or your own results!