If you using a gameport you can increase the resoloution by using a
larger value pot. For example if you use a 100K pot over half its
rotation you'd get say 0-50k. Stick a 400K pot in the same arrangement
and you get 0-200k. Or use a quarter of the 400K pot's rotation and get
0-100k. The resolution of most pots are fairly good, so as long as the
mechanism for rotating the pot is fairly solid, without much play, then
the amount of pot rotation isn't that important as long as the
resistance range is reasonable. You would probably "feel" more
resolution by making sure that the pedals have a reasonably good throw.
The biggest limitation is the analogue gamport. It basicly measures the
time to charge a capacitor. Put more resistance across, lowering the
current, and it takes longer for the capacitor to charge giving a
higher count. If you use a small resistance range then you get limited
number of counts and poorer resolution. Use to large a pot and it takes
too long to perform the measurement (charge the capacitor) giving lags
in controller input. Also higher resistance will result in lower current
passing through the cables making noise more noticeable (ie the
jitters). So in the end, selecting the pot size (resistance range) is a
trade off between resolution and controller lag (jitters). There are a
few things you can do to reduce the jitters (use the lower resistance
end of the pot, short cable runs, good shielding) but there is a limit.
If you check the output of most analogue controllers, you'd probably
find the resistance peaks at around 50k to 100k. If you can use a
digital device, as other have suggested, that may be more what you are
looking for. Maybe try one of the gameport to USB converters.
There was a good description of the gameport and how digital gamecards
tried to overcome some of these limitation at
http://www.gplonline.com/tech-talk/hardware-tech.htm but the site
appears to be gone.
But look at it this way, if you get stable counts of say around 0 to
300 for 3 inches of pedal travel then every 0.01 inch of pedal movement
will be detected. :-)
HTH
Ken
>Suggestions/input/ideas wanted: As a personal project I want to
>design a set of pedals that will give a high and fine degree of
>control (yeah... buy some high-end pedals -- but I like to build
>stuff, ok?). On examination of the pedal internals I have personally
>seen (not many) it seems to me that depressing the brake/throttle only
>results in the pot turning a small percentage of its potential, a
>basic 1:1 movement. I am thinking that a simple gear reduction box
>may translate a pedal throw of a few inches into a pot revolution
>somewhere between 180 and 270 degrees. I am not an engineer, but it
>seems to me that this would result in a finer degree of control,
>especially throttle control. In fact, if I recall correctly, wasnt
>the old T2 pedal unit based on this design? Do any of the current
>mass market and/or high-end pedals use a similar design? Anyway, any
>input from this group would be useful.
