We occasionally get asked about potentiometers with operational arcs that are different to the standard 270′ or our own custom 50′ version.
Rob Smallwood gave us this idea which involves using a log pot such as that shown by curve L in this diagram [for the Vishay part number P11S1V0FLSY00103KL].
The curve is almost linear from 10% upwards, this can be used in conjunction with a programmable controller such as the Pro-150 or the SST by setting the start or zero point appropriately [parameter 13 for the Pro-150].
A zero point of 10% will give an arc of around 135′ but this approach can be used to give almost any arc required.
The end point of the arc can also be selected via parameters 12 & 14.