[sdiy] Potentiometer related questions

[Scott Bernardi]

"Taper" reference to the shape of the tapped resistance vs. rotation curve.  If you
measure the resistance between one end terminal and the middle terminal and plot the
resistance as you turn (rotate) the shaft, a LINEAR taper means that equal changes of
rotation create equal changes of resistance - a straight line on a resistance vs. %
rotation plot.
A LOGARITHMIC (sometimes called AUDIO taper) has a curved response.  Oftentimes it is
approximated with two staright line segments, one at a lower slope, and then a
breakpoint at about 66% rrotation into a higher slope.
Alps is a manufacture of high quality potentiometers used in mixers and other high end
audio gear. Most like they have their own approximation of a logarithmic taper which is
being referred to as the "Alps taper". I'm not sure what this actually looks like, or
how it compares to a "European taper".
In synth gear, most of the time you are going to want to use linear taper pots. The
place where you would use logarithmic taper pots in in places where you are setting
volume levels (mixer inputs, FM inputs, overall gain of a VCA, etc.).
I have a page that talks more about pots at
http://home.attbi.com/~sbernardi/elec/og2/partsub_pots.html

David Hughes wrote:

> Folks,
>
> Two potentiometer related questions :
>
> 1. What does the term 'Taper' mean?
>
> Quoting from the Farnell catalogue with respect to ALPS potentiometers :
>
>         "Alps Taper designation is opposite to standard European versions"
>
> 2. I need a good quality, cheap 10K linear potentiometer with a height of around
> 26mm, base around 26mm x 26mm. Omeg have provided pots which are slightly too tall.
>
> All suggestions appreciated.
>
> Regards
>    David
> --
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> Infection Music
> http://www.infectionmusic.co.uk
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