Good morning, synthfolks.
Apparently there are already two topics about ribbon controllers but since i’m using another approach i think it justifies another topic.
My references for this build are this video of these guys doing a teardown of the otamatone. From this i take 3 conclusions. They’re using velostat sheets, they use two strips of it and the strips seem to be connected to wires through a crimp terminal connector.
The two strips are one on top of the other like this:
Another reference is this blogpost.
https://bluesyncline.gitlab.io/otamatone/index.html
This reinforces the use of the crimp terminal as an interface.
So far i’ve been able to recreate the behavior of the ribbon controller as seen in this video.
But there are problems i wasn’t able to solve and i’d like the help of you guys to try to solve it.
In this example i didn’t use a crimp connector to interface with the velostat, i’m using wires and tape.
the circuit is a simple voltage divider:
And what are the problems?
- The audio is very noisy
- The pitch variation is exponential where it should be linear
To try to solve the exponential problem i tried to use this circuit
It didn’t work as expected but it might have been an error of execution.
I have no idea how to deal with the noise problem, but i suspect it might be related to the interface between the velostat and the wires.
This is about it. Any help is appreciated. Thanks for reading!
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Hi, take a look at Kontinuum lab on YouTube.
His approach to using velostat material is remarkably effective as an FSR. He seems to focus more on the field effect rather than contact and this produces less noise (i reckon but not 100% sure).
Do keep us posted.
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Did you ever make any progress here? I’m curious about this project.
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I have been experimenting with velostat material but nothing to report beyond that i have managed to reproduce some of what’s on the video. Anyone else have a go?
I was considering purchasing some velostat myself but wasn’t quite sure what length I’d need. I was considering making a poor mans otamatone bit it looks like they double over the strip on top of itself. Most of what I’ve seen is 11inches max, and I wasn’t sire that would be sufficient.
I do have a (knock-off) circuit board design but unsure how to reverse engineer it.
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I bought a pack of a4 ESD bags for protecting circuits from static. They are made of a velostat material, also known as linqstat. They are polymeric foil embedded with carbon to make them slightly conductive. If i remember it was only a couple of pounds and i have enough now to make a 50 foot otamatone. (no, i wont and you cant make me)
There is nothing to prevent you adding strips of the plastic together as it’s the conductive strips above and below that velostat layer that need to be continuous for the circuit. Just dont overlap the material or you’ll have a different response at that point, which might be fun: i just added that to my playlist.
Sandwiched under a ribbon pot (for pitch) the velostst layer will give you the ability to use its output as a means of expressing volume or any other effect you want just by varying how hard you push. Two layers or more and you have even more expression ability.
I ended up making a couple more prototypes and managed to improve the manufacturing process a bit. It seems like the gap between the velostat strips is indeed necessary.
This teardown of the otamatone is far more detailed. https://youtu.be/m97DfpA9MLI?si=REeKk2XpSHZxW3bT
I’m planning to build another prototype after i’m done with a couple of boards. I’m gonna use a flexible plastic substrate from a folder and punch bumps on one of them with a phillips screw or something like that. The best solution for the connection to a wire is to clamp metal on the velostat. I’m going to use those crimp connectors, pre solder the wire and clamp it to the velostat.
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So, i built the new prototypes. In this video i’m testing the second one without the noise. https://youtu.be/igod0jssFSA?si=i4kT7DgDLtBNSxK-
This is the video where i tested both prototypes https://youtu.be/LSY-8PrCB5Q?si=Y12uAKxXHAlr7EFk
The description goes into more detail about the construction. "Hard plastic substrate, a velostat strip for the resistive element and separation of the layers by a 1 mm foam tape.
Video 1 shows a ribbon controller made of 2 velostat strips against each other in a 2 terminal device. Video 2 shows a controller with one velostat strip and one conducive tape arranged in a potentiometer like circuit.
Controller 1 has an exponential behavior while controller 2 is more linear."
Kinda like this
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