[sdiy] when to use LIN POTS and when to use LOG?

[David Brown]

Go to http://www.mindspring.com/~clist/PotGraph.html and plug in 5 
volts, 100K and  100K and you can see the non-linearities.  On my 
potentiometers, 6 is about 50%, so I just turn them all a bit higher 
than the numbers to sum to 10.

If I understand you correctly, you have it backwards.  You want a 10K 
pot with a 100K input resistor to the op amp in an inverting configuration.

Dave


At 07:08 PM 12/10/2009, megaohm wrote:
>I'm with Dave on this. But to really get a linear response (ie: 12' 
>equals half the input signal) you need a 100K pot wired as a voltage 
>divider wired across a 10K resistor. A ten to one ratio pot to input 
>resistor. 100K pot and 100K resistor gives linear behavior for the 
>first 10% or so then the curve will go 'log-ish'. Works for me!
>   Generally, there is no right or wrong. Experiment. Get some log 
> pots to try out. It depends entirely on the circuit and your 
> personal preferences.
>
>p.
>
>
>On Thu, Dec 10, 2009 at 2:54 PM, David Brown 
><<mailto:davebr at earthlink.net>davebr at earthlink.net> wrote:
>At 08:07 AM 12/10/2009, dan snazelle wrote:
>i know that LOG are for volume.
>
>
>I've stopped using log pots for volume.  I much prefer linear since 
>most of my modules have multiple inputs.  I have to make sure I 
>don't over drive the input by summing together 2 or 3 inputs.  With 
>linear pots I can pretty much add up the numbers and be reasonably 
>sure I'm close to the right level.  With 100K pots and 100K input 
>resistors, the controls are a bit non-linear but they are close enough.
>
>Dave _______________________________________________
>
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