linear pot and resistor in series/perallel changes taper?

[nognow]

does putting a linear pot and resistor in series/parallel changes the taper?

[GibsonGM]

Hi, why don't you check this article out?   There are ways to change tapers and how pots act, yes, and R.G. has done a great job of showing us how!

http://www.geofex.com/article_folders/potsecrets/potscret.htm

[nognow]

I actually want the opposite haha...I want it to REMAIN linear 

[GibsonGM]

Ohhhh...ok - a resistor in series with a pot should not change the taper.
I don't THINK, offhand, that putting another R in parallel will, either, but you may want to sim that and take a look....or just do it and see what you get using an ohmmeter - you should be able to tell what's going on by meter.

[Seljer]

If you're using all three lugs (i.e. not as a variable resistor) and if you put a resistor over the outer lugs the taper doesn't change. Only the input impedance (so that'd be affecting its interaction whatever stage is prior to the potentiometer) without much affect on the output impedance it presents to the next stage.

Same applies to wiring a resistor in series, what changes are various interactions due to different impedances.

If you were to use a linear pot of a high value (lets say 100k) and you hook it up as volume control to something with a very low input impedance (lets say only 1k) it would 'load down' the pot considerably and you'd be getting very non-linear behavior from a linear pot.



If you put two resistors, one from lugs 1 to 2 and one from lugs 2 to 3 you get a kind of "S" taper, with a linear bit in the middle and more exponential behavior at each end.

[nognow]

If you're using all three lugs (i.e. not as a variable resistor) and if you put a resistor over the outer lugs the taper doesn't change. Only the input impedance (so that'd be affecting its interaction whatever stage is prior to the potentiometer) without much affect on the output impedance it presents to the next stage.

Same applies to wiring a resistor in series, what changes are various interactions due to different impedances.

If you were to use a linear pot of a high value (lets say 100k) and you hook it up as volume control to something with a very low input impedance (lets say only 1k) it would 'load down' the pot considerably and you'd be getting very non-linear behavior from a linear pot.



If you put two resistors, one from lugs 1 to 2 and one from lugs 2 to 3 you get a kind of "S" taper, with a linear bit in the middle and more exponential behavior at each end.

I will indeed be using the pot as a variable resistor,you think it would become non-linear?

[Seljer]

I will indeed be using the pot as a variable resistor,you think it would become non-linear?

If its wired in parallel it will distort the taper. Observe the last image the the article on geofex http://www.geofex.com/article_folders/potsecrets/revser.gif

Wiring a resistor in series won't have any ill effect, it's just simple addition.

[nognow]

I will indeed be using the pot as a variable resistor,you think it would become non-linear?

If its wired in parallel it will distort the taper. Observe the last image the the article on geofex http://www.geofex.com/article_folders/potsecrets/revser.gif

Wiring a resistor in series won't have any ill effect, it's just simple addition.

Ohhhh...ok - a resistor in series with a pot should not change the taper.
I don't THINK, offhand, that putting another R in parallel will, either, but you may want to sim that and take a look....or just do it and see what you get using an ohmmeter - you should be able to tell what's going on by meter.

thanks!

[GGBB]

I will indeed be using the pot as a variable resistor,you think it would become non-linear?

Series - no, but parallel - yes.  A linearly variable resistor in parallel with a fixed resistor takes on a logarithmic (or anti-logarithmic) taper - in other words audio or reverse audio.  Audio for a clockwise decrease in resistance; reverse audio for clockwise increase.  The amount of taper 'distortion' is inversely proportional to the size of the fixed resistor: as it drops, the taper becomes less and less linear.  Whether or not you will be able to notice the difference depends on the values of the two resistors: if they are the same, the taper will only be slightly non-linear and may not be noticeable.  The application - where and how you are using it - will also matter.