Vex Analog Inputs

Does anyone remember/know what the Input range of the Analog Sensors is in Ohms??

I seem to remember 10K Ohms, but 100K Ohms is also familiar.

Also when using a Potentiometer, is Audio-Taper better, or should I go with Linear-Taper. I would think Linear-Taper would be better, but somewhere I seem to remember that Audio-Taper was recommended by someone in the know.

I was searching the FAQ’s, but did not locate that exact information.

Thanks in Advance…

Hey MarkO,

I assume you are asking about wiring a potentiometer across the 0-5V power pins, and having the wiper (center) contact go to the analog input?

The Vex potentiometer is a 10K linear taper pot wired this way, so I’d recommend using 10K linear.

However, the analog input is a voltage input, so any potentiometer range can be used, if you have something else on hand.

Lower resistances (like 1K) will burn a bit more power all the time (25mW), whereas higher resistances like 100K will burn less (0.25mW).

The resistors that are built into the Vex microcontroller inputs will introduce a small “error” into the voltage provided by the potentiometer. Larger value potentiometers provide less current out, so they will be more effected by this error, and smaller value potentiometers will be effected less.

You almost certainly want linear taper. Log or audio tapers are really only good for very specific applications, and are probably not really useful for angle sensing.


  • Dean

Thanks Quazar!!

That is exactly what I needed to know.