Ice blonde wrote:
Hi Dan


The movement of the rheostat in the sender is linear but the
hinge's location creates a sine function to the indication, with the
top travel being rather slow and the lower travel moving much more
quickly.


I've notice something similar in cars, do you think this is cause by
the same thing?

Yes, although I have seem some where the designer used a progressive
wind on the rheostat to linearize the output. However, this probably
costs 5 cents more per part so I've seen this only very rarely.

Matt