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Topic: Aproaches for sensing Velocity and pressure of a button (pad) ? (Read 172 times) previous topic - next topic

cheche_romo

Well, it's been a long time since I wanted to do something like this, but I have no idea of how to apprach this. What I want to do is some pads for a music instrument, Something like Maschine Pads or APC Pads (a 4 x 4 matrix of pads, capable of sensing pressure, and velocity of the "hit")

 I've been reading and researching and I came to the idea that they use a carbon printed sheet in between the pads and the PCB, but I have no idea of how that works, and finding something useful on the Internet is almost impossible, because I don't even know what to search.

I also found out Strain gauges, maybe this could be another way?, but how, if you need one amplifier for each pad, or can you multiplex the sensing?( having a multiplexer that cycles the output of each wheatstone bridge to the input of the Amplifier )

Im not really sure how to go about this, so if anyone has worked on something like this and can share a word, it would be greatly appreciated!

 :)  :)  :)  :)

gdsports

Take look for tutorial information at SparkFun and Adafruit on Force Sensitive Resistors. I have not seen an example of it used for drum pads but it might work.

cheche_romo

Take look for tutorial information at SparkFun and Adafruit on Force Sensitive Resistors. I have not seen an example of it used for drum pads but it might work.
I don't thinks this is a cost effective approach, I mean $7.95 * 16 pads at least ( around $128 for 16 pads, this is super expensive), that is why I am searching for an alternative, I thought of strain gauges to be the most cost effective solution (€ 0,41 per pice on Aliexpress), But I'm not sure this is a feasible approach, I have never used one.. But the idea doesn't seem to crazy..   :smiley-yell:

gdsports

http://www.sensorfilmkit.com/


6"x4" sensor material for $18. If you cut them into 1" squares, 24 sensors for $18.

cheche_romo

http://www.sensorfilmkit.com/

6"x4" sensor material for $18. If you cut them into 1" squares, 24 sensors for $18.
Wow, thanks this is much better, but how about long term durability?? , I don't think is reliable to long term, because the material will change its properties every time physical stress is applied, it never comes 100% to its original state, making it not "reliable" for a music instrument :(

Is there a way to go with a "carbon" sheet? (I'm saying carbon because I don't really know what they are.)

here is an example of how they look like:  Pad Sensor Sheet

I might also think that it can be made of a piezoresistive material, right?

So if anyone know anything about this, I'll really appreciate if they can point me out to the right direction.


gdsports

I have not used the sensor film yet. There is a lot of information on their website. For questions about the film, I suggest contacting the company via their website Contact tab.

cheche_romo

I have not used the sensor film yet. There is a lot of information on their website. For questions about the film, I suggest contacting the company via their website Contact tab.
Thanks, will do. =)

allanhurst

Electric pianos often used  switches  with 2 contacts, and timed the delay between them making to acheive various effects.

Strain gauges are a very bad idea, as they are not cheap , their output is very small, and the sensitive amplifiers required to measure them are slow.

Not a good thing for a musical instrument.

Allan

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