Introduction: PUSH-PULL WINE GLASS RESONATOR
The impact that the Resonance phenomenon has on the Universe is indisputable. I still remember when my science teacher several years ago introduced me to the concept of Resonance . Many examples were provided but due to my youth, or life inexperience I was not able to understand it very well. The truth is that this concept (Resonance), explains a number of phenomena that we see around us, for example: the movement of a swing and the way in which we make it work, the tragic fall of the Tacoma Narrows Bridge in 1940 and its design errors as well as when electrical signals are tune in communication devices. It is also evident in Nuclear Magnetic Resonance Imaging (NMR), the working principle of many musical instruments, etc. Have you seen that some singers are capable of breaking wine glasses with just their voice? Wow, it always seemed spectacular to me and it was one of the examples that remained in my memory in those magnificent lectures. It always made me wonder how they knew they could do that. Breaking a glass in that way is not at all a simple task, it requires training and certain qualities that I certainly do not possess.
In this INSTRUCTABLE I am offering the steps for the construction of a device capable of making vibrate wine glasses in a similar way to how those singers do with the sounds they emit.
This device is capable of easily breaking a wine glass if it does not have a wall thickness of at least 2mm. In my experience with this project and after some initial testing, even the 2mm wine glass which was used for testing got lightly damaged even though half the volume of the amp was not exceeded. Keep a safe distance and always wear PROTECTIVE googles!
Unlike other experiences I have seen, this project has not only one speaker, but four! Additionally, the speakers are configured in two pairs, and the electrical signals for each pair are 180 degrees out of phase, making it highly efficient in this regard.
My proposal does not require special laboratory instruments such as Signal Generators, Frequency Meters, Amplifiers and Ultra Powerful Horns. It was made from recycled materials, in some cases discarded from other equipment.
With only four small speakers, a small Bluetooth audio amplifier, an old tablet or cell phone and certain parts made on a CNC or 3D printer you can make your own version of this project.
Since it is remotely controlled via audio signals sent by Bluetooth, it is completely safe, even if you just want to break wine glasses and not just make them vibrate!
Breaking wine glasses with your voice while exposing your unprotected face to them as shown in certain videos On YouTube, I think it is not wise!
It is important to note that this project is particularly useful in school settings, where students could be actively involved in its construction. This would enhance understanding of this concept from an early age.
Plexiglas Sheets (recycled), 3mm thick, new product available at: https://amzn.to/2v3uV86 (In total a total of 1334cm2 of this material was used).
Instant Glue https://amzn.to/3b5ucm8
2Inch Audio Speakers Full Range (4 total), (recycled), new product available at: https://amzn.to/2UkFHAB
Duplex Electrical conductors 1m, (recycled) 18-22awg, new product available at: https://amzn.to/2UCy3AB
Soldering Iron https://amzn.to/2J3ifkU
Audio amplifier https://amzn.to/3akuR3q
Oscope (free Android App) https://play.google.com/store/apps/details?id=org.sbaudio.oscope
Frequency Generator (free Android App) https://play.google.com/store/apps/details?id=com.luxdelux.frequencygenerator
L Framing https://amzn.to/3buqIKb
Electrician screw driver set https://amzn.to/3ddoUXW
CNC Machine https://amzn.to/2Uj6Q5P a 3D Printer could also work (STL Files available)
Endmill 1.5mm https://amzn.to/33xyKQ0
Wine glass (Your choice, (2mm-3mm to vibrate only)
Safety Goggles https://amzn.to/2UkoFmh
Sound protection headphones OPTIONAL https://amzn.to/33RlSE8
Screw Box M3 and M4 https://amzn.to/3aGI6uV
Neodymium Magnet OPTIONAL https://amzn.to/38DuLSA
Step 1: SOME INITIAL NOTES
What is meant by Resonance?
Resonance is the increase in amplitude of oscillation of an electric or mechanical system exposed to a periodic force whose frequency is equal or very close to the natural undamped frequency of the system.
For example, let's present the case of a child rocking on a swing. Initially the child is sitting on the swing at rest, to start the swinging movement it is necessary to remove it from this position and release it. As this goes back and forth, with its movement begins a series of energy transformations, from Gravitational Potential Energy to Kinetics, from Kinetics to Gravitational Potential and so on. Since there are friction forces on this system, if we do not continue pushing or if the child does not self-propel, little by little the amplitudes of the oscillations will gradually decrease until they are in the same position that they had initially. How do we propel the child and support the oscillations? Although we are not aware of this, we propel the child by applying the phenomenon of Resonance. The swing is a pendulum, with an oscillation frequency determined by its length. The repetitive force we make to maintain the oscillations of this pendulum is carried out at regular time intervals, the inverse of this time (frequency) coincides with or is very close to the oscillation frequency value of the swing.
What are the theoretical and practical foundations of this project?
Hit a wine glass with your fingernail and place it close to the ear, what do you hear? A sound, generally sharp. Whenever you hit the glass you will hear that sound as long as you keep the glass intact (do not pour any liquid into it, paste an object to it, hold it differently, etc.). The frequency of that sound is called the Normal Frequency of that particular wine glass. The wine glasses are quite good oscillating systems and they are made of glass, so certain singers can break them with their voices, how is this possible? Similar to what happens on a swing, singers make a loud sound whose frequency is equal to or very similar to the Normal Frequency of the wine glass they are trying to break. With this they manage to increase the mechanical oscillations of the wine glass to a point that the structure cannot resist and breaks.
Why does this project have 4 small speakers, why is it necessary to regulate the height of the speakers and target a specific region of the glass?
In short, to make it vibrate more easily. If you analyze the photo I am sharing on this project, you will notice that the speakers point to the top of the glass. The greatest oscillation amplitudes are reached in this region and with this it is possible to make them vibrate more efficiently. Small speakers make it possible to better focus actions on this area. Since all the wine glasses are not the same, this project makes it possible to regulate the height of the speakers easily, managing to concentrate the action of the emitted sound, in any case.
The speakers are facing each other in 2 pairs. The amplifier signals being sent to each pair of speakers are 180 degrees out of phase, why this? Simple, do this experiment. Find a plastic glass that you can easily deform without breaking. Press the mouth of the glass towards its center with two fingers of your hand and…what do you see? The region where you press enters the center of the glass, but the rest moves away from the center. If we can get a pair of speakers to emit a "push" sound, similar to the force of the fingers, while at the same time two others emit a "pull" sound, then a system capable of vibrating the glass easily will be created, even with relatively low sound powers and such small speakers. As the sound is emitted, the pushing and pulling actions of each pair of speakers alternate.
Using small speakers, a small amplifier, flat pieces of Plexiglas to assemble and Android App applications, this project could be distributed as an experimental kit for demonstration purposes for the school, which could easily fit in a small cardboard box.
If a straw to absorb liquids is placed inside the wine glass while the experiment is being carried out, it will be possible to notice that the cup IS VIBRATING VIGOROUSLY. To show the Resonance phenomenon, it is not necessary to break the cup, although if you want, use a thinner wall cup and increase the volume level a little. Also take the appropriate security measures. The wine glass almost does not vibrate if the frequency that is played changes a little with respect to the proper frequency of the wine glass of the experiment, something that is easily verified by changing the frequency of reproduction in the Android App.
Step 2: ELECTRICAL CONNECTIONS BETWEEN SPEAKERS
In this step the electrical connections between the speakers are made. For this, four pieces of duplex cable 25cm long are cut. Each cable has colors or markings that identify its polarity, for example, red corresponds to positive and black to negative. In my case, I identified the cable with the white bands as positive and the black one as the negative. The speakers also have polarity markings. Using the soldering iron, make the joints at each contact of the speakers, being consistent with the polarity of the cables chosen.
Subsequent to this, strip the remaining ends of the cables and join each pair of cables with the same polarity. At the end you should have 2 pairs of speakers, in each pair the positive and negative conductors are joined together.
Step 3: CUTTING THE DESIGNED PARTS ON THE CNC
The working area of my CNC machine is 200mm * 300mm. Since I used a 3mm thick recycled Plexiglas, the original size of which differed from my machine's work area, I had to cut rectangles that fit my machine. For this I used a Table Saw. If you buy the Plexiglas in the link that I recommend, this step is perhaps unnecessary.
In all my cuts I used the 1.5mm EndMill that I declared in the list of materials. In this step I have attached the design drawings in DXF, the G-CODE of each piece and also the 3D STL files for which you want to print the pieces on a 3D printer instead of cutting it. Using DXFs I think they could also be cut on a LASER cutter. In total 20 pieces are required in my design.
Step 4: ASSEMBLING THE PARTS
The U-shaped piece is the base, this base has a horizontal slot. Insert the largest piece into this slot as shown in the image. Using the L framing and a magnet guarantee the perpendicularity between them. Put a few drops of instant glue on the joint and wait a few seconds until the glue takes effect. Remove the L framing and the magnet and continue to glue the entire contact region between the two pieces. To reinforce the union some pieces were designed for such effects as shown in the image. Spread some instant glue on its perpendicular edges and attach it to the structure you are creating.
One of the designed pieces is the one that supports the speakers. Using two screws, nuts and flat washers, fix these parts to the support with slots for sliding. Take into account the height suggestions in correspondence with the glass you have.
Using corresponding screws, nuts, and washers, secure each speaker to its bracket. At the end you will have something very similar to the image shown.
Step 5: CONNECTING TO THE AMPLIFIER
For the correct execution of this project, it is required that the connections to the amplifier are those conceived in the design. Let's review it again. Each speaker has two contacts, one positive and one negative, distinguishable by a mark. In our case we had chosen the duplex cable, the positive conductor is the white band and the negative is the black. The white band cable has been soldered to the positive contact of the speaker and the black to the negative. The remaining ends of these cables from a pair of speakers have been soldered following the following principle: White band (positive) cables are soldered together just like black cables. In no case may the black and white band cables make electrical contact with each other. The amplifier's contacts also have polarity. The red ones are the positive ones and the negative ones the blacks. To achieve the correct phase shift, one pair of speakers connects to the amplifier with the correct polarity and the other pair connects to the reverse polarity, that is, the positive cables of the speakers to the negative terminal of the amplifier and the negative cables to the positive terminal.
Step 6: DETERMINE THE NORMAL FREQUENCY OF THE WINE GLASS
With the help of OSCOPE (Android App) it is easy to determine this value. Start the application, bring the microphone of your cell phone or tablet closer to the glass while you tap it SLIGHTLY and it sounds, write down the value detected in the application. There may be harmonics, but the value that interests us is the highest peak detected. Another way and it is the one I used, is to moisten one of the fingers and slide it gently over the edge of the glass until a sound is generated and is detected by the application. If you have any way of recording what happens on the cell phone screen while the application is running, do it for the record and in case you have doubts about the range it reaches, you can review the values frame by frame. In my case the frequency was approximately 789Hz.
Step 7: THE EXPERIMENT
Arrange each pair of speakers so that the speakers of each pair are facing each other. When you perform this step, verify that the bases come together in a circle. Turn on the amplified Bluetooth and wirelessly connect the Tablet or cell phone to it. Program the Frequency Generator application with the Normal Frequency of the wine glass. Place the cup in the center of the speakers with a straw to absorb liquids inside. If the frequency emitted by the speakers is correct, the straw will bounce off the walls of the glass. Again if the wine glass is thin- walled or if the volume of the amplifier is more than half, there is a danger that the cup will break and pieces of glass will scatter. Stay alert and take the protection measures stated in previous steps. Change the frequency value in the Frequency Generator application to a different value, you will see how the straw hardly moves.
Close the app and turn off the amp. When you remove the wine glass, use caution, it may be broken and you may not have noticed it.
Step 8: MY CONCLUSIONS
The Push-Pull effect of this project, on a wine glass, has been shown to be effective in this type of Resonance experiment. I believe that those who decide to elaborate it, based on the explanations and steps I give here, will obtain a better understanding (in case they do not have it) of this very important phenomenon on which we base many scientific-technological applications.
We are living difficult times these days and the education (instruction) of the youngest, in many cases is being carried out at home. Running experiments to support the theory with them is essential to their training.
Don't forget to check my other projects, maybe you can find other interesting ideas:
I will be aware of the comments. I will answer any question and suggestion. Good luck!
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