Potentiometers to the cRIO, what resistance?

[pafwl]

On the old platfrom (pre 2009), we used 100K ohm potentiometers connected to the analog inputs on the robot controller.

On the cRIO what resistance do I get? 100K ohms or 10 K ohms. I looked everywhere and cannot find the answer.

Any help is appreciated....

[thefro526]

We are using a single turn 10K Ohm Potentiometer on our CRio and it works well.

[EricVanWyk]

Take a look here:
http://www.chiefdelphi.com/forums/sh...ad.php?t=89482

[pafwl]

Gents thank you for your speedy reply...

If I already have a 100k 10 turn pot that I may or may not have used in the past (2005) on a tower and it worked well, what is the difference between using that 100K ohm pot on the cRio vs. a 10K ohm pot?

Is one more noisy or more sensitive?

Clearly I am not an electrical engineer.

[thefro526]

A 100K Pot should be 10x More sensitive than a 10K Pot.

With a 10K 10-Turn Pot you'd have a change of 2.77 Ohms per Degree where as a 100K 10-Turn Pot would have a change of 27.77 Ohms per Degree.

Then again, I'm no Electrical Engineer either.

[Alan Anderson]

Originally Posted by pafwl

Is one more noisy or more sensitive?

Sensitivity is not really an issue for a potentiometer. The way it's connected, you're just producing a voltage output. The voltage depends on the ratio of resistances, and the absolute resistance values are not important.

A lower resistance is theoretically going to be less noisy, as any stray noise source will have an easier path to ground and thus put less voltage on the signal.

Read the thread Eric linked to for more specific advice.

[pafwl]

If I use the AnalogModule->GetAverage. That should take the spikes out, Yes/No?

I use that for my IRSensors.

[EricVanWyk]

Please just read the thread linked to earlier.

Originally Posted by thefro526

A 100K Pot should be 10x More sensitive than a 10K Pot.

With a 10K 10-Turn Pot you'd have a change of 2.77 Ohms per Degree where as a 100K 10-Turn Pot would have a change of 27.77 Ohms per Degree.

Then again, I'm no Electrical Engineer either.

This is wrong. Please do not offer advice that you are unsure of, as it only confuses people.

[pafwl]

I tried the old one tonight. It worked. I am using the AnalogModule Get Average function. I was getting a range of 46 to 969. Then the potentiometer broke.

Someone on this thread said it best, you get what you pay for.

Thanks for all your help.