I am planning on making a musical instrument where I require the conversion of vibration of a material to voltage. The idea is to make a percussion instrument where I hit a plate made of a certain type of material. Based on the different areas on which I hit the plate, the vibrations will be different and after converting the vibrations to voltage, I will take the FFT of the signals to differentiate the different areas on which I hit the material and map it to produce a particular sound. I know that piezoelectric sensor is a material which converts pressure to voltage but I am not sure if it will be robust enough. Is there any alternative I can use?

 

Strain gauges and accelerometers come to mind.

 

Something like this -

https://www.element14.com/community...56-accelerometer-level?displayFullThread=true

A Bluetooth implementation -

https://www.digikey.com/en/articles/techzone/2015/dec/cypress-psoc-4-ble-bluetooth-low-energy

Regards, Dana.

 

A piezo disc transducer should be robust enough, unless you are hitting the plate with a sledge-hammer.

 

Something like this -

https://www.element14.com/community...56-accelerometer-level?displayFullThread=true

A Bluetooth implementation -

https://www.digikey.com/en/articles/techzone/2015/dec/cypress-psoc-4-ble-bluetooth-low-energy

Regards, Dana.

Cool. Another thing I have in my mind is to use a seismometer which prompts me to ask a question. What is a seismometer sensor made up of? If it is a made of piezoelectric material, then that's of no use. If it can help in distinguishing vibrations better, it will be useful.

 

A piezo disc transducer should be robust enough, unless you are hitting the plate with a sledge-hammer.

Really? That's great. I will have to test it though and get back to you.Robust in the sense that it should be able to distinguish between the hits in different areas of the plate.

 

Reminds me of gated reverb.

 

Cool. Another thing I have in my mind is to use a seismometer which prompts me to ask a question. What is a seismometer sensor made up of? If it is a made of piezoelectric material, then that's of no use. If it can help in distinguishing vibrations better, it will be useful.

Imagine a permanent magnet speaker where the cone is replaced by a weight. The movement of the weight moves the speaker coil inside the field of the magnet producing a voltage.

 

A seismometer is like a speaker with a heavy voice coil .I used one to detect hits on a paper target; 64 ohm VC, 1/4 W, 1.5 in. dia. with 1/2 X 1/2 thin wall Al tubing cemented to VC. Another uses a 17 mm piezo disc on a 20 mm brass disc with a dead LR41 battery cemented to center. Whole thing cemented to a 2 mm X 30 mm plastic disc with a 18 mm hole in center. Works well with paper target ; could mount it to your plate with 2 narrow strips of double faced adhesive tape.
Does it not work with a microphone and amp. ?
Are you making a steel drum ?

 

Using my piezo geophone attached to Al plate with alligator clip, measured 8 V PP, 250 Hz fundamental with lots of harmonics which tapered off to 0 V in about 40 msec. when taped with a wood stick. Plate was suspended with rubber bands.

 

I am planning on making a musical instrument where I require the conversion of vibration of a material to voltage.

Strain gauges and accelerometers come to mind.

That would be my thinking but using an accelerometer and a single axis accelerometer. The type used for acoustic testing. You would choose one for a specific G force range and frequency response. Here are a few examples. There are likely a dozen manufacturers who make this type.

Also as mentioned Piezoelectric accelerometers are well suited for what you want to do and are inexpensive so it really depends on what you plan to spend and to what uncertainty you want the measurements?

Ron

 

I am planning on making a musical instrument where I require the conversion of vibration of a material to voltage. The idea is to make a percussion instrument where I hit a plate made of a certain type of material. Based on the different areas on which I hit the plate, the vibrations will be different and after converting the vibrations to voltage, I will take the FFT of the signals to differentiate the different areas on which I hit the material and map it to produce a particular sound. I know that piezoelectric sensor is a material which converts pressure to voltage but I am not sure if it will be robust enough. Is there any alternative I can use?

I worked on a research project that was for a sensor that measured higher frequency vibration of steel materials. .Depending on the degree of accuracy that you want, there are quite a few choices. But the highest output will indeed come from a PZT transducer disk. These are available from many different sources and won''t cost much. But you do need to insulate the disk from the plate. Have fun experimenting. I certainly did!!

 

A piezo crystal is used for such things normally, but I do not know the exact type. However your problem does not come from the crystal alone, it comes from the audio amplifier after it, which needs to be very good for this purpose. Normally this is used for air instruments (like a clarinet which has a microphone at the end). But this is specialized audio electronics, so be prepared for testing and failure, or find someone who knows what he is doing.

 

The idea is to make a percussion instrument where I hit a plate made of a certain type of material. Based on the different areas on which I hit the plate, the vibrations will be different and after converting the vibrations to voltage, I will take the FFT of the signals to differentiate the different areas on which I hit the material and map it to produce a particular sound.

Thinking about this a little more what you are describing is along the lines of what I always called a steel drum or steel pan. Anyone who has enjoyed the sounds of a steel band knows how amazing the instruments sound, especially considering most were hand fashioned from 55 gallon drums.

I know that piezoelectric sensor is a material which converts pressure to voltage but I am not sure if it will be robust enough.

A good accelerometer will be plenty robust enough. Again I am speaking about accelerometers similar to those pictured below which come in a wide range of mounting configurations and shapes and sizes.



You may want to give Signal Conditioning Piezoelectric Sensors a read through. Place some emphasis on charge amplification. So you start with a sensor and then work your amplification scheme and then worry about your FFT or whatever you wish to do with the data.

Ron

 

The idea is to make a percussion instrument where I hit a plate made of a certain type of material. Based on the different areas on which I hit the plate, the vibrations will be different and after converting the vibrations to voltage

Any material will vibrate dependent on its hardness and physical dimensions. You'll find this true if you take a steel pipe and bang on it in different locations. You'll still get the same frequency. Tone may change a little but the vibrations are going to be reactive to the size, shape and hardness of the material.

Sounding like you want to make something like those steel drums you hear in typically Caribbean style music. Those steel drums start out as simple steel drums. The metal bottom is pounded in different places to thin out the materials and cause different stress levels within the steel, which is why you see them rapping on the drum in different locations causing different tones. But just where you strike a steel drum is a product of where you stressed the steel by stretching it through impact. It takes a while to get one into the right tune, and I don't think they retain their tuning very long. Once they lose their tune I don't think they can be restored. Maybe changed to lower frequencies or something, I'm not the expert on those things. But what you're asking to do will certainly be a challenge.

I've played drums. And drums come with symbols. Depending on how I struck them they'd respond lightly or with a crash. But they always produced the same tone. Except for the bubble shape at the top, called "the bell". Even then, if you listen close to the tone you still hear the same resonant frequency.

As for converting vibrations into musical notes, an electric guitar does it with a magnet and a coil of wire. The magnet sits still within the coil. When the steel string is plucked it changes the magnetic field, causing a small voltage in the coil. That voltage is picked up and amplified. However, you can trick the string into double vibrating (that's what I'm calling it, don't know if it's a correct term) where you touch the string in a location where the string will actually simulate a sine wave, half of the string swinging (lets call it) left while the opposite end of the string swings right. Still, it's a resonant frequency of the string.

I want to watch this thread to see if you make any progress on your project. I'm curious to see how this turns out.

 

A seismometer is like a speaker with a heavy voice coil .I used one to detect hits on a paper target; 64 ohm VC, 1/4 W, 1.5 in. dia. with 1/2 X 1/2 thin wall Al tubing cemented to VC. Another uses a 17 mm piezo disc on a 20 mm brass disc with a dead LR41 battery cemented to center. Whole thing cemented to a 2 mm X 30 mm plastic disc with a 18 mm hole in center. Works well with paper target ; could mount it to your plate with 2 narrow strips of double faced adhesive tape.
Does it not work with a microphone and amp. ?
Are you making a steel drum ?

I'm making an electronic version of an Indian classical musical instrument called Mridangam.
https://www.google.co.in/search?q=m...69i57j35i39.3549j0j7&sourceid=chrome&ie=UTF-8

 

You will discover that the signal from the string vibration is quite different from the signal from the body vibration. Just consider the electric guitar as an example of that. So here is a suggestion for a means of converting the vibration of the instrument body into an electrical signal. Find an old phonograph cartridge, a crystal one would be best because of the much higher output voltage. Replace the needle portion with a similar diameter sewing needle, and that will be something that can probe the instrument body until you find the location that gives the sound that you want. You will need to feed the signal from the pickup into a high impedance amplifier input to get the right frequency response.