Very interesting stuff about wheels

Recently I have converted my TSW Sport to be switchable between separate and combined throttle and brake. I suddenly found that I was locking up the brakes much too easily when I switched to separate axes and so did some further work. I have discovered some very interesting stuff about controllers (TSWs in particular), GPL and probably other sims as well. I intend to put all of this on a web page soon but here are some tit-bits. I have also discovered a few ways to reduce pot bounce (jittery or spikey pots). I have probably got some of the electrical physics wrong but I believe that I am correct about the effects. Please correct me where I am in error - I would love some feedback - good or bad on this. It can make a big difference to both brake and throttle sensitivity by switching between separate and combined pedals but this difference IS ADJUSTABLE!!!! I have discovered that by fiddling with the overall pot ohmage and "at rest" resistance you can make your car behave quite differently!! I would rate the net effect nearly as important as car set up in say GPL (which is the only sim that I have tested this on). Basically with combined pedals you are passing through two pots in series. Depending on the "at rest" point of each pedal pot you are varying a higher electrical resistance across a relatively wider band than with separate pedals. And this band is only linear if both pedals have the same amount of travel. I restricted my range of travel on the brake by sticking a squash ball inside the pedal mechanism to make the brakes less soggy but I over-compensated for this by opening up a tightening***inside the TSW Sport to allow me to be more sensitive with my braking. I believe that you can muck about with any reasonable quality wheel in this way. So as soon as you switch to separate pedals you presumeably make both pedals linear - WRONG - THE LINEARITY IN GPL DEPENDS ON THE AT REST POSITION OF THE POTS!!!!! (Oh yes it does, Steve Blank.) By monkeying with the "at rest" position of the pots you can make the brakes more or less linear and thus reduce or increase the chances of locking up. You can do the same with the throttle and I guess that, here, different settings will be better suited to different tracks. In case you think I using logarithmic pots - I am not. I am compiling some basic pot setup tips which I shall post shortly. It will be broadly based on the raw data figures - see TMS (an invaluable Thrustmaster utility) or, if you can't get hold of this, GPL's configuration screen is adequate, but takes much longer to load and unload. I have also been testing with 50K and 100K pots which, as you might expect affects the brake throttle behaviour as well. How about non-linear pots! Well they're pricey but could be good for the brake pot (possibly unfair - I'm sure the virtual FIA might object to the use of these). A standard pot has a total travel of about 330 degrees which is about the same as the steering wheel - so there's not a lot you can do with this. The other things I have found out are to do with pot bounce which obviously has a major negative effect on the car. Low raw numbers decrease pot bounce. If you have bounce in your wheel adjust the "at rest" settings on your pots - but bear in mind that it will affect the car in other ways. The other things you can do to reduce pot bounce are: 1) Clean the pots. Use a hydrocarbon fluid based electrical contact cleaner. 2) Replace the pots if they are old or damaged. 3) Use 50K pots rather than 100K - again this will affect car performance. 4) Use a game port with an adjustable speed and turn it up to the top (usually 10) - ignore what TMS says - don't centre it, just turn it up high. 5) Make sure both wheel and pedals are grounded. Thomas has ignored the twisted ground wire that runs around all the others wires going to the 15-pin gameport on my TSW. You should run this to a loop that is screwed to the pot rod just like a washer for each of your pots. I got this idea by looking inside my Thrustmaster Formula 1 - a big omission by Thomas. Am I right here - it seemed to make a big difference. Cheers, Paul

<<So as soon as you switch to separate pedals you presumeably make both pedals linear - WRONG - THE LINEARITY IN GPL DEPENDS ON THE AT REST POSITION OF THE POTS!!!!! (Oh yes it does, Steve Blank.) By monkeying with the "at rest" position of the pots you can make the brakes more or less linear and thus reduce or increase the chances of locking up. You can do the same with the throttle and I guess that, here, different settings will be better suited to different tracks. In case you think I using logarithmic pots - I am not.>> Hmmmm; interesting stuff.......where to begin. I'll try this, with the caveat that I'm an electrical dunderhead. So feel free to enlighten me. Assume your pedals both have equal travel, mechanically. Regardless of the raw resistance readings inherent in the pots, they will have a certain minimum and a maximum value at the ends of pedal travel, both roughly the same for separate axis pedals if the pots are affixed equally. If by "monkeying" with the "at rest" positions, you mean adjusting the static position of the pot shaft to use a different portion of its possible travel, then yes, you will alter the raw resistance numbers. However, when you calibrate the pedals in Windows or a game, the pertinent software driver "learns" how to interpret those numbers. The driver matches its own min/max/center numbers, etc. to the relevant resistance values. The game will then use the numbers from its assigned driver, not the raw resistance readings. I use a CH utility called to test my controllers, as it allows you to see the readings from the gameport or the Windows driver readings, with or without using the calibration settings. It's surprising how different they can be on some controllers. As for linearity, if you use linear-taper pots you will always get a linear response from a controller, unless the game's software modifies the input, ala GPL's linearity slider. My previous suggestion about holding down on the pedals a bit to set the beginning actuation point would indeed result in a steeper response line. It would still be a line rather than a curve, though, and one that began later in the pedal's mechanical travel. The purpose of doing this is to compensate for the weak springs in some pedals, as foot weight can tend to actuate them unintentionally, and also to balance the response of both pedals to suit the user. There's no rule here; it's just something I experimented with and found helpful. You can have earlier actuation with shallower response line or later actuation with steeper response line, with equal or different profiles on each pedal. I expect ten different drivers would end up with ten different settings(at least :-)), but it is a useful "off-the-menu" setup tool. I have seen past reference on r.a.s. to using audio-taper pedal pots for less touchy response , but haven't tried it myself. In the States you can get 'em at RadioShack for around $2 apiece, about the same as their linear-taper ones. They stock pots in resistance readings from 50Kohm up to 1Mohm, but they'd need modifying to use in most pedals or wheels I've seen, as they don't have the typical half-round shaft end. As for lower raw numbers being more stable, I'd agree with that. When I was using a TM GP1 with my CH pedals, the steering readings, from a 200K pot, were much jumpier than those from the 100K pedal pots. Furthermore, some games (F1RS, for instance) couldn't handle the difference in values and never would recognize the GP1 and CH pedals simultaneously. The Logitech wheel I'm using now has a built-in A/D converter, which eliminates the gameport-related pot noise you notice in GPL as shaky driver arms. Cheers, Steve B. remove "edy" from address for email

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> Assume your pedals both have equal travel, mechanically. Regardless of > the raw resistance readings inherent in the pots, they will have a certain > minimum and a maximum value at the ends of pedal travel, both roughly the same > for separate axis pedals if the pots are affixed equally. If by "monkeying" > with the "at rest" positions, you mean adjusting the static position of the pot > shaft to use a different portion of its possible travel, then yes, you will > alter the raw resistance numbers.

Yes, this is what I mean. I cannot argue with your logic - it seems impeccable - BUT I have tested this to my own amazement and can assure you that if you set the raw numbers on the brake pot as low as possible you will have an initially less responsive brake pedal - not exactly a dead zone but tyre lockups will cut in later. Why this is I have no idea. I have not tested on the generic input of GPL just direct input. Also 50K pots appear to exacerbate the effective dead zone. I'm fast coming to the conclusion that potentiometers are not the ideal solution. I have no idea how optical "pots" work nor have I tried them but perhaps these represent a significant improvement. Papyrus are the only people who can answer this. It's a good idea. I shall try them. Oh, for the ideal wheel! I am getting sick and tired of opening my wheel up every so often to adjust, clean or replace pots. My ongoing battle to eliminate pot noise entirely is a long way from won. 50K pots do help but I don't want a less responsive throttle. In separate mode I am coming to the conclusion that a 50K brake and a 100K throttle maybe best. I haven't done enough work on the steering but this is just as crucial. Cheers, Paul

And another interesting factette - I left my internet (serial to USB modem) connection open and went into TMS. The pots were bouncing around like mad flies and the port speed had dropped considerably. I quit my connection, and reentered TMS and the port speed was back to normal and the pots were bouncing only slightly - as normal. Ooo-err. Time for a USB wheel with optical pots, methinks. Maybe I'll get the Microsoft one - any other USB wheels with optical pots? Which is best? Cheers, Paul

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> <<So as soon as you switch to separate pedals you presumeably make both > pedals linear - WRONG - THE LINEARITY IN GPL DEPENDS ON THE AT REST POSITION OF > THE POTS!!!!! (Oh yes it does, Steve Blank.) By monkeying with the "at rest" > position of the pots you can make the brakes more or less linear and thus > reduce or increase the chances of locking up. You can do the same with the > throttle and I guess that, here, different settings will be better suited to > different tracks. In case you think I > using logarithmic pots - I am not.>> > Hmmmm; interesting stuff.......where to begin. I'll try this, with the > caveat that I'm an electrical dunderhead. So feel free to enlighten me. > Assume your pedals both have equal travel, mechanically. Regardless of > the raw resistance readings inherent in the pots, they will have a certain > minimum and a maximum value at the ends of pedal travel, both roughly the same > for separate axis pedals if the pots are affixed equally. If by "monkeying" > with the "at rest" positions, you mean adjusting the static position of the pot > shaft to use a different portion of its possible travel, then yes, you will > alter the raw resistance numbers. However, when you calibrate the pedals in > Windows or a game, the pertinent software driver "learns" how to interpret > those numbers. The driver matches its own min/max/center numbers, etc. to the > relevant resistance values. The game will then use the numbers from its > assigned driver, not the raw resistance readings. I use a CH utility called to > test my controllers, as it allows you to see the readings from the gameport or > the Windows driver readings, with or without using the calibration settings. > It's surprising how different they can be on some controllers. > As for linearity, if you use linear-taper pots you will always get a > linear response from a controller, unless the game's software modifies the > input, ala GPL's linearity slider. My previous suggestion about holding down > on the pedals a bit to set the beginning actuation point would indeed result in > a steeper response line. It would still be a line rather than a curve, though, > and one that began later in the pedal's mechanical travel. The purpose of > doing this is to compensate for the weak springs in some pedals, as foot weight > can tend to actuate them unintentionally, and also to balance the response of > both pedals to suit the user. There's no rule here; it's just something I > experimented with and found helpful. You can have earlier actuation with > shallower response line or later actuation with steeper response line, with > equal or different profiles on each pedal. I expect ten different drivers > would end up with ten different settings(at least :-)), but it is a useful > "off-the-menu" setup tool. > I have seen past reference on r.a.s. to using audio-taper pedal pots for > less touchy response , but haven't tried it myself. In the States you can get > 'em at RadioShack for around $2 apiece, about the same as their linear-taper > ones. They stock pots in resistance readings from 50Kohm up to 1Mohm, but > they'd need modifying to use in most pedals or wheels I've seen, as they don't > have the typical half-round shaft end. As for lower raw numbers being more > stable, I'd agree with that. When I was using a TM GP1 with my CH pedals, the > steering readings, from a 200K pot, were much jumpier than those from the 100K > pedal pots. Furthermore, some games (F1RS, for instance) couldn't handle the > difference in values and never would recognize the GP1 and CH pedals > simultaneously. The Logitech wheel I'm using now has a built-in A/D converter, > which eliminates the gameport-related pot noise you notice in GPL as shaky > driver arms. > Cheers, > Steve B. > remove "edy" from address for email

to my own amazement and can assure you that if you set the raw numbers on the brake pot as low as possible you will have an initially less responsive brake pedal - not exactly a dead zone but tyre lockups will cut in later. Why this is I have no idea.<< Never been accused of impeccable logic before! But I'll bow to testing; it sounds pretty interesting. I wonder if it's due to the mismatch between pot values, since you're tweaking only one. That would parallel my experience with the TM wheel/CH pedal setup. Second that. I'm pretty happy with my current setup, but as soon as an all-digital, pot-free alternative surfaces ( at a sub-stratospheric price), I'm in there! Happy Tweaking, Steve B. remove "edy" from address for email

Strange; I just looked at mine and the internet connection has no effect at all on my pot readings. Perhaps Logitech's A/D converter makes the difference; it really does away with all the pot noise. There aren't too many offerings out there in USB/Optical wheels. Saitek use MS guts, but I tried one of theirs and didn't care for it at all. The MS is probably the only such choice for now, but I expect that won't last long. Pot-based controllers are on the endangered species list already. They won't be missed! Steve B.

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>And another interesting factette - I left my internet (serial to USB modem) >connection open and went into TMS. The pots were bouncing around like mad >flies and >the port speed had dropped considerably. I quit my connection, and reentered >TMS >and the port speed was back to normal and the pots were bouncing only >slightly - as >normal. Ooo-err. Time for a USB wheel with optical pots, methinks. Maybe I'll >get >the Microsoft one - any other USB wheels with optical pots? Which is best?

remove "edy" from address for email

% 3) Use 50K pots rather than 100K - again this will affect car % performance. Just one thought on this one... The pot's ohmage and peformance is also tied to one's gameport quality and bus speed. -- **************************** Michael E. Carver ************************* Upside out, or inside down...False alarm the only game in town. =-=-=-=-=-=-=-=-=-=-=-=-=-=-=<[ /./. [- < ]>=-=-=-=-=-=-=-=-=-=-=-=-=-=

Hi Steve, I'd be very keen to know the exact spec of the wheel, converter and gameport you are using. It sounds like you are much more on top of the pot noise problem than I am. I have tried the MS wheel/pedal combo in a store demo and wasn't too impressed. This latest discovery that the modem connection affects my wheel/pedals is most disturbing but does, at least partially, explain why I can usually get better times in practice than I can on VROC. Cheers, Paul

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> Strange; I just looked at mine and the internet connection has no effect at > all on my pot readings. Perhaps Logitech's A/D converter makes the difference; > it really does away with all the pot noise. > There aren't too many offerings out there in USB/Optical wheels. Saitek > use MS guts, but I tried one of theirs and didn't care for it at all. The MS > is probably the only such choice for now, but I expect that won't last long. > Pot-based controllers are on the endangered species list already. They won't > be missed! > Steve B. > >And another interesting factette - I left my internet (serial to USB modem) > >connection open and went into TMS. The pots were bouncing around like mad > >flies and > >the port speed had dropped considerably. I quit my connection, and reentered > >TMS > >and the port speed was back to normal and the pots were bouncing only > >slightly - as > >normal. Ooo-err. Time for a USB wheel with optical pots, methinks. Maybe I'll > >get > >the Microsoft one - any other USB wheels with optical pots? Which is best? > remove "edy" from address for email

Hi Michael, I'm using Thrustmaster's ISA ACM gameport. Obviously the ISA bus is a slower than PCI which is slower again than USB. What products could I get to accomodate my existing gameport based wheel/pedal combo? What other steps can I take to eliminate pot noise and the seeming interference I am getting between my modem and my game port. Thanks in advance, Paul

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> % 3) Use 50K pots rather than 100K - again this will affect car > % performance. > Just one thought on this one... The pot's ohmage and peformance is also > tied to one's gameport quality and bus speed. > -- > **************************** Michael E. Carver ************************* > Upside out, or inside down...False alarm the only game in town. > =-=-=-=-=-=-=-=-=-=-=-=-=-=-=<[ /./. [- < ]>=-=-=-=-=-=-=-=-=-=-=-=-=-=

Hi Paul - I'm currently using a Logitech wheel, the Wingman Formula (non-FF), plugged into an Ensoniq AudioPCI card. The A/D converter is an integral component of the wheel. I was unaware it had one until one of the guys at Logitech (who've been very helpful!) mentioned it in response to a query of mine about the pot stability. You'd think the marketers would trumpet that sort of thing. Apparently, there's also some averaging of the pot values done at a firmware level, further reducing noise. I had suggested it might be marginally overdamped, but I'm probably just revisiting the old A/D - CD/LP argument of years ago. We know how that turned out. I've seen a number of mentions of the wheel's stabilty with other soundcards, so I don't think that's at issue. The Logitech's not a perfect setup out of the box, but it's pretty easy to tweak into a nice package. Cheers, Steve >>I'd be very keen to know the exact spec of the wheel, converter and gameport you are using.<< remove "edy" from address for email