[sdiy] Very cheap SPI pressure sensors.. anybody ??

[Mike Bryant]

I think the resistivity of paper is higher though so if you charged a plate on one side to a fairly high alternating voltage (not mains ! :-), you might see a difference in signal level in a high impedance amplifier aligned to each row of holes.

-----Original Message-----
From: Synth-diy [mailto:synth-diy-bounces at synth-diy.org] On Behalf Of Ingo Debus
Sent: 20 March 2021 13:11
To: synth-diy
Subject: Re: [sdiy] Very cheap SPI pressure sensors.. anybody ??


> Am 19.03.2021 um 20:46 schrieb cheater cheater <cheater00social at gmail.com>:
> 
> Forgot to describe what the PCB would look like. You have a square 
> area split into two rectangles. Those rectangles are two plates of a 
> capacitor. Above it is a solid square of metal (foil, plate, ...).
> This one has no split. It's not connected anywhere. The closer it is 
> to the two plates below it, the more the capacitance changes.

You mean, you can detect punched holes in paper this way? I doubt it. The relative permittivity of paper isn’t that big.
It could work if the piano roll is not made of paper but of some conductive foil.

Ingo
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