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On some synthesizers, there is a strip called ribbon controller, to wipe your finger over and it detects pressure. It's a bit similar to a mobile phone's LCD touch panel, except that it is one-diagonal (horizontal only) and the accuracy is (probably) less. It's typically around 10cm/4" and the amount of pressure is normally not checked (just pressed or not). Also simultaneous presses are not supported.

It is used for adding an effect to a sound, like vibration (pitch), volume, filter cutoff or other effects.

It looks like the black square in the buttom left (under the joystick).

I have an idea to make something like this myself, but I was wondering how it is called in 'electronic' terms. I tried to search for ribbon controller, but I get some Play Station 4 ribbon 'controller' which I don't think is the same. It is also possible to buy readily made separate ribbon controllers but these cost like 300 euro and normally come with a MIDI box (while I want to create my own functionality, MIDI related or not).

So, what is the name of such a strip/touch/pressure sensor? enter image description here

Michel Keijzers
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2 Answers2

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The most basic ribbon controller is a linear potentiometer, or a resistive touch sensor. Your finger sets the wiper position. It might be easier to do it with a linear capacitive touch sensor and microcontroller. I'm not aware of commercially-available pots in this form factor.

More advanced controllers also have integrated force sensors, similar to those you find in synth pads, that respond separately to the linear sensor. You will have to find a way to assemble the two sensors yourself. (Maybe a stack like capacitive touch sensor pcb/rubber/pressure sensor).

vofa
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  • Thank you... I was hoping to make this easily; I don't need force, although it might add an extra dimension. Thanks for this insight. – Michel Keijzers Jan 17 '18 at 09:26
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Linear SoftPot (Ribbon Sensor). For a small one maybe just buy it but they get very expensive for big ones.

Here is a clever DIY design that seems long lasting enough to be practical. https://www.youtube.com/watch?v=14NgkS1hm0I

For pressure you could use this project. Capacitive sensor with a twist. https://hackaday.io/project/9465-strumpad They stuck a piezo disk under the pcb so the pressure of pressing the board makes voltage read as force. Should be very robust and sensitive.

People also muck about with velostat. Pressure sensitive resistivity plastic. More pressure = less resistance. It is apparently how some aftertouch pressure sensors in midi keyboards are made.

If you are already using a raspberry pi, some people use cheap phone digitizers for multitouch capasative sensor. You could maybe add piezo under glass for pressure sensing in addition.

Audo Voice
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