> A colleague of mine is looking at using a membrane strip potentiometer
> as a touch sensor. This is a three-terminal device, just like a
> typical pot, except that the wiper is only connected when pressure is
> applied. In effect, the wiper is actually whatever point or points of
> contact are made between the top foil layer and the bottom resistive
> layer.
>=20
> We were both puzzled to discover that the datasheet for this part
> lists both a max and a MIN voltage. Max voltage is obvious for thermal
> reasons. However, we are not sure why a minimum voltage is listed.
> They list their standard product as rated from 5V to 30V and then they
> state that custom products can be made with ratings ranging from 1V to
> 60V. This seems to indicate that the 5V lower spec is not simply a
> typical value listed for convenience but that there would really be
> some undesirable condition to using a lower voltage.
>=20
> My colleague would like to run this at 3.3V since that is the system
> voltage in his device. Does anyone here have any idea why there would
> be a minimum voltage spec and what the impact of operating this device
> at 3.3V (when 5V is the minimum rating) would be? The only idea I was
> able to come up with is that perhaps there is a certain amount of
> voltage noise present due to operation of the part and that 5V is the
> lowest voltage at which the accuracy specs would not be affected by
> the ratio of the supply voltage to the voltage noise.

My reaction is why not use a capacitive touch sensor? What requirements spe=
cifically call for this sort of sensor?
Microchip have a capacitive touch sensor demonstration kit that has a slide=
r type element as one of the possible.
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