Hi John and
to the forum.
The controller basically uses the voltage signal being output from the potentiometer
(rather than resistance values) to control the motor power/speed.
The potentiometer effectively operates as a simple variable voltage divider which varies the signal voltage relative to rotary movement.
If the overall resistance of the potentiometer is too low, it could overload the +5V supply.
Conversely, if the resistance is too high, the voltage drop could reduce the amount of usable travel of the potentiometer.
I have previously suggested using a 10k Ohm potentiometer as a throttle control for the VEC controllers, which has been proven to work fine:
The
2k Ohms and 1.5k Ohms resistors shown in the diagram above are required to ensure the throttle signal voltage stays within the controller's working range:
Without these resistors, the
Throttle voltage range protection is likely to be activated at both ends of the potentiometer's travel
(i.e. below 0.7V or above 4.0V) causing the motor to cut out
(accompanied by a 12 beep/blink error code).
If the resistors are not used, the
Throttle voltage range protection enable value would need to be set to
2:Disable to prevent the 12 beep/blink error from being triggered. However, this could prove to be extremely dangerous if the ground wire going to the potentiometer suddenly failed due to vibration etc.
(and became completely disconnected) while the controller was powered up, as the motor could then start running at maximum speed, regardless of the potentiometer position!
A 5k Ohms potentiometer should work fine, as it would only be placing ~1mA load on the +5V supply, but you would probably need to use lower value resistors
1 kOhm on the +5V supply and
750 Ohms on the ground wire
(with a 5k Ohms potentiometer) to keep the signal voltage within the expected range.
Alan 
