I need precision variable resistors for a programmable analog computer that I'm trying to construct.
An analog computer requires variable resistors that can be set with precision.
I don't want to use digital components because the have discrete steps and are not pure resistors (have capacitance)
My first thought was to connect a dc motor via reduction gears to a precision rheostat -- wire that to a digital ohm meter and build a control circuit that dials the rheostat to the desired value.
Are there off the shelf components that I can buy or will I have to construct my own.
On using a MOSFET as a variable resistor -- based on this post, it looks like it will be difficult to deal with the nonlinear behavior -- plus the ohomic range seems narrow.
I looked at digitally controlled rheostats but they have several limitations including the fact that they are active solid-state components and that they have discreet steps (typically 256 and 1024 on the high end.