RPM Fluctuation with JimStim
 

OK, I have MS to the point of testing the unit with the JimStim. All functions seem to respond normal except RPM. It is very erratic while adjusting the pots. Have done several searches but cannot seem to make sense of it.
Is this normal with the stim or do I have a problem?
Frustrating how long it takes ME to understand this shit............

The pots used on the jimstim aren't the highest quality units in the world, and they are linear, which means that they behave non-linearly when used to control inputs which are scaled for non-linear sensors (temperature).

For RPM, I set the "fine" pot to mid-scale, use the "coarse" pot to get close to the RPM I want, and then use the "fine" pot to achieve it. Sometimes you run our of range and have to brush the "coarse" pot with your finger (don't actually grasp it, just brush it) to bump a couple hundred RPM.

Thanks Joe. I will move on with my build, having passed all the tests so far.