POT part values

[Michael]

Great -- I'll play with some cap values.

I'm stuck with a 500K trimmer in an exisiting design.

Hopefully, POT doesn't take to long to execute as my program needs to keep moving or I could have some problems.

Thanks.

[sayzer]

Great -- I'll play with some cap values.

I'm stuck with a 500K trimmer in an exisiting design.

Hopefully, POT doesn't take to long to execute as my program needs to keep moving or I could have some problems.

Thanks.

I guess, you will need to use 1nf for 500K pot to get the same linearity as 100nf with 5K POT.

__________________

[Acetronics2]

Hi, Sayzer

A Happy new year for the Two sides of the Bosphor.



No ...

You do have to stick to the 50k - 0.1µF @ 4Mhz harware config. other values will give much limited range and great loss of granularity and precision - Sorry Glenn, but dozen of tests have been run ...

POT doesn't work at all as RCTime ...

I think many threads have been launched on this sublect during the past years - including the POT mechanism description ...

Alain

[Michael]

Thanks.

A definitive answer indeed.

Guess I'm out of luck then. The cap is there for noise then?

[Glenn]

Thanks.

A definitive answer indeed.

Guess I'm out of luck then. The cap is there for noise then?

Due to the manual its..

"The resistance is measured by timing the discharge of a capacitor through the resistor (typically 5K to 50K)."

And it really looks like its done this way too.

[Glenn]

You do have to stick to the 50k - 0.1µF @ 4Mhz harware config. other values will give much limited range and great loss of granularity and precision - Sorry Glenn, but dozen of tests have been run ...

Well, what can I say, it works fine for me with 20K and 220nf.. I get around zero and 254 at the endstops, and linearity that is good enough for me, actually I just tried to pout the value on a darrel-bargraph (Yea, I do love them ) and it "feels" right when turning the pot looking at the bargraph.

Maybe its not ideal, but at least its good enough for me, and probably most people ?

..But if I can choose the value (In this case there was a pot inbuilt that I wanted to use) I'll think about it.