Yamaha CS80

--- In yamahacs80@yahoogroups.com, "David Rogoff" <david@t...> wrote:
> 
> The results are in the files pressure_vs_voltage.xls and
> aftertouch_response.jpg in the Files page.  It's a kind of log
> response, toping out with a little under 7 volts for any force over 
70
> oz (about 2Kg).  The response is a little weird: it would stay the
> same for several ounces and then jump.  I'm not sure why it did 
this.
>  Maybe it's stiffness in the rubber piece over the sensor. 


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?

 David