Re: precision potentiometer use in steering wheels

[email hidden] wrote in message <7u1t14$kl7$[email hidden]>...

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>Hi. I'm hoping some of you technical minded guys can provide some >additional input on this subject. In a PC steering wheel a true >precision potentiometer will likely give better and more precise >signal input and resolution, but I have heard (just someone's casual >opinion) that a pc game port is not sensitive enough (or "precision" >enough, as it was put to me) to take advantage of high precision >input. I believe that the Thomas' wheel uses a Spectrol bushing mount >conductive plastic pot with Linearity of 2%. Would a ball bearing >conductive plastic pot with Linearity of less than 0.5 (or better) >yield even better results? or is there a limitation imposed by the >sensitivity of a game port? Has anyone experimented with using very >high (industrial/military grade) precision potientiometers in their >wheel? >

We have used nearly every type pot available in all resistor types, several resistance ranges etc and have seen very little to no difference in any of them, other than longevity, there are people who will swear that this or that type of pot will do this or that (usually because thats what they happen to use) but dont buy into that. We use 3 different types now with the best being the Spectrol, sealed, conductive plastic type which are supposedly good for millions of cycles, so far they have worked quite well but a PC gameport will probably always be just that and not precision enough to make any apreciable difference. Now we'll probably see about a dozen messages saying this is BS but we've got well over 6 years experience and several thousand wheels in everyday use to back my opinion. Trev

Hi. I'm hoping some of you technical minded guys can provide some additional input on this subject. In a PC steering wheel a true precision potentiometer will likely give better and more precise signal input and resolution, but I have heard (just someone's casual opinion) that a pc game port is not sensitive enough (or "precision" enough, as it was put to me) to take advantage of high precision input. I believe that the Thomas' wheel uses a Spectrol bushing mount conductive plastic pot with Linearity of 2%. Would a ball bearing conductive plastic pot with Linearity of less than 0.5 (or better) yield even better results? or is there a limitation imposed by the sensitivity of a game port? Has anyone experimented with using very high (industrial/military grade) precision potientiometers in their wheel?

you need a good gameport. At the moment.. the best actually apears to be the MX300.. I've had expereince of a few, PDPI SB LIVE MX300 SB PRO The MX300 is a true Digital game port and is fantastic.. gave me about half a second a lap instantly!!! But.. it isn't the steering that need the precision.. the most important is the brake and then the accelerator.. they need th MOST precision inputs possible.. The wheel is important.. but you will be steering with opposite lock.. steering in.. steering out.. so fast that it isn't as important to have a huge resolution. Just some thoughts James Pickard [email hidden] wrote:

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> Hi. I'm hoping some of you technical minded guys can provide some > additional input on this subject. In a PC steering wheel a true > precision potentiometer will likely give better and more precise > signal input and resolution, but I have heard (just someone's casual > opinion) that a pc game port is not sensitive enough (or "precision" > enough, as it was put to me) to take advantage of high precision > input. I believe that the Thomas' wheel uses a Spectrol bushing mount > conductive plastic pot with Linearity of 2%. Would a ball bearing > conductive plastic pot with Linearity of less than 0.5 (or better) > yield even better results? or is there a limitation imposed by the > sensitivity of a game port? Has anyone experimented with using very > high (industrial/military grade) precision potientiometers in their > wheel?

On Wed, 13 Oct 1999 12:14:54 GMT, [email hidden] wrote:

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>Hi. I'm hoping some of you technical minded guys can provide some >additional input on this subject. In a PC steering wheel a true >precision potentiometer will likely give better and more precise >signal input and resolution, but I have heard (just someone's casual >opinion) that a pc game port is not sensitive enough (or "precision" >enough, as it was put to me) to take advantage of high precision >input. I believe that the Thomas' wheel uses a Spectrol bushing mount >conductive plastic pot with Linearity of 2%. Would a ball bearing >conductive plastic pot with Linearity of less than 0.5 (or better) >yield even better results? or is there a limitation imposed by the >sensitivity of a game port? Has anyone experimented with using very >high (industrial/military grade) precision potientiometers in their >wheel?

I would say the nicest solution is an optical encoder and USB interface, but I don't know of any wheels that have both. The gameport seems to be more of a problem than the pot. My LWFF is very smooth after 9 months of use, has been since new, and the steering pot is still working great through the USB interface. If you want to improve the feel of your analog wheel, better to focus on the gameport than the pot in my experience - unless your pot is worn out. Some sound card gameports work well, other don't, and the custom game cards are another option. Keith.

I replaced the steering pot in my T2 with a high-grade conductive plastic pot, and noticed no difference at all. I believe that the standard gameport is indeed not sensitive enough to benefit from a more precise pot. Unless you use a PDPI gamecard or something similar, it's probably not worth the hassle. When you consider how a standard gameport goes about determining where the controller is positioned at a given instant in time, there are too many other variables involved for the quality (linearity, anyways) of the pot to be a dominant factor. For a much better explanation than I could ever give, take a look at: http://www.hut.fi/Misc/Electronics/docs/joystick/index.html There is a very good explanation of how the gameport works and its inherent limitations. The biggest improvements I have seen in controller precision and response have come with increases to processor and bus speed. Using a C300 overclocked to 450 with a 100MHz bus is pretty much perfect, response and accuracy are no longer issues, now it's come down to my limitations as a driver. All this makes sense, since the faster your machine is, the more often it can monitor the gameport, hence greater response times and resolution. Hope this didn't bore you shitless. Zog [email hidden] wrote:

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> Hi. I'm hoping some of you technical minded guys can provide some > additional input on this subject. In a PC steering wheel a true > precision potentiometer will likely give better and more precise > signal input and resolution, but I have heard (just someone's casual > opinion) that a pc game port is not sensitive enough (or "precision" > enough, as it was put to me) to take advantage of high precision > input. I believe that the Thomas' wheel uses a Spectrol bushing mount > conductive plastic pot with Linearity of 2%. Would a ball bearing > conductive plastic pot with Linearity of less than 0.5 (or better) > yield even better results? or is there a limitation imposed by the > sensitivity of a game port? Has anyone experimented with using very > high (industrial/military grade) precision potientiometers in their > wheel?

I also own a LWFF and I've hardwired my old Thrustmaster pedals onto it. The LWFF (and maybe other FF wheels) seems to filter the signal coming from the pots and eliminates all the noise coming from them. (I think, also short peaks due to a little bit worn pot are filtered out). AFAIK, the PDPI does the same. I don't know, if a 'precision' pot really beats a new cheapo one regarding generated noise and linearity, but for sure it will last longer. Peter Vienna, Austria keith <[email hidden]> schrieb in im Newsbeitrag: [email hidden]...

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> On Wed, 13 Oct 1999 12:14:54 GMT, [email hidden] wrote: > > >Hi. I'm hoping some of you technical minded guys can provide some > >additional input on this subject. In a PC steering wheel a true > >precision potentiometer will likely give better and more precise > >signal input and resolution, but I have heard (just someone's casual > >opinion) that a pc game port is not sensitive enough (or "precision" > >enough, as it was put to me) to take advantage of high precision > >input. I believe that the Thomas' wheel uses a Spectrol bushing mount > >conductive plastic pot with Linearity of 2%. Would a ball bearing > >conductive plastic pot with Linearity of less than 0.5 (or better) > >yield even better results? or is there a limitation imposed by the > >sensitivity of a game port? Has anyone experimented with using very > >high (industrial/military grade) precision potientiometers in their > >wheel? > > > I would say the nicest solution is an optical encoder and USB interface,

but I > don't know of any wheels that have both. The gameport seems to be more ofa > problem than the pot. My LWFF is very smooth after 9 months of use, hasbeen > since new, and the steering pot is still working great through the USB > interface. > > If you want to improve the feel of your analog wheel, better to focus onthe > gameport than the pot in my experience - unless your pot is worn out. Somesound > card gameports work well, other don't, and the custom game cards areanother > option. > > Keith.

Pickard <[email hidden]> schrieb <snip> > The MX300 is a true Digital game port and is fantastic.. gave me about > half a second a lap instantly!!! Just out of interest: What is a 'true digital game port'? AFAIK, all gameports have to digitize the analog signal coming from the pots. So why is the MX300 'more digital' than others? <snip> Peter Vienna, Austria