Yamaha CS80

Hm, very interesting.  So it is a discrete array of printed thick-film 
resistors and a 9-tap conductive switch with 'rolling' contacts.

  This is not how most modern FSRs work; those use a sandwich of two 
contact layers and a resistive layer.  The more pressure applied, the 
better (lower) the resistance gets.  Yamaha's design is very interesting, 
though if those rubber buttons start to dry-rot new ones might be tough to 
obtain.  New ones could be made (the circuit board part is almost easy) by 
an injection-molding neoprene plastics place.

  What values of resistance are measured for each tap?

Scott
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On Wed, 6 Oct 2004, David Rogoff wrote:

> Well, I looked inside the sensors (see "sensor guts.jpg" in the Files 
> page), and it makes more sense.   Each sensor has a divider chain of 
> resistors with 9 taps that come out under the (conductive) rubber 
> pad.  You can see the rubber pad on the left is on its side, showing 
> the angle on the underside.  As you press the key harder, the pad 
> makes contact with more of the taps, pulling off higher voltages.  
> This explains the jumps I measured.
> 
> Scott, do you know if most FSRs work like this?