potentiometer specifics

[Mad Hitter]

Curious what pots people are using with this. I saw some posting a while back that the different pots were having an impact on output and i want to make sure I get the best chance at max range. I'm not that familiar with the effects of various potentiometer specifics have on a circuit, i.e. dna can use 1k to 10k... whats the difference between the two in regards to how they effect the circuit performance and function.

 

[WillyB]

No answers?

Well a lot of times almost any trimmer can be used (kinda). The DNA12 datasheet provides no real info like a chart or formula to help determine the best choice.

Different values will affect the granularity of the adjustment range.

If you look at the popular LM2596 assemblies the trimmer is made to handle a range of ~1.25V-37V. Will it work for us who may want about 3.3V-5.5V? Sure it will. But there is only a small range of turns in our range and once you get there small movements will give you twitchy, rather abrupt results. If we were building from scratch using the same chip would we want the same trimmer value? Nope. By using the datasheet we can determine a better combo of trimmer and resistor, capping our lowest and highest voltages at either end of the trimmer.

Here is an example of a mod that will work, it's just poorly designed and more finicky to use.

Note how much of the trimmer is lost. With the correct value trimmer (and on extra resistor in series) the entire range of the trimmer can now be used, adjustments will be much smoother and easier to fine tune.