rec.autos.simulators

are potentiometers especially affected by noise/interference?

are potentiometers fragile and could I have ruined them by getting them
too hot with a soldering iron etc?

if so is there a way to shield them from it?

what is the best way to wire up a wheel/pedal setup so that it can be
switched from 1 axis gas/brake to 2 axis?

The reason that I ask is that I have tried building my own setup but
always end up with what looks like the potentiometers affecting each
other.

Yes, C.J., they can be affected by RF.
Again, yes.  The carbon type are not quite so fragile as the newer polymer
film type but in both cases you should use a heatsink when soldering and
ensure that the iron is held to the joint for as short a time as possible.
Do this by cleaning and fluxing the wire and post, which will lead to a
faster soldering job.
See above regarding using a heat sink.
It would be necessary to see the existing wiring diagram before answering
that.

Unlikely

I have a homemade setup, works great.  One 100K pot on the X-axis.  2 in
series on the Y-axis, each operating over about a 30K range.

Sounds to me like a wiring problem.

Hi Cj !

You can get all the info You want about building steering wheels (and
calibrate them) at Walt Ottenads page (just do a search on Walt
Ottenad). Good luck.

F

Unless you picked up a book on how to solder copper pipes at the home
center and are attempting to extrapolate how to solder electrical
connections with a MAPP gas torch. (Yes, you can eventually damage
them, but they are far sturdier than most semi-conductor devices, so
you have to***up the soldering pretty bad to damage them.)

Get a better soldering iron or better technique. Unless you tried to
overheat them or suffer from narcolepsy while soldering, they're
probably fine.

DPDT switch. One setting needs to have them "added" together. The
other setting drives each pot as a separate load to two different axes
on the game port.

They might affect each other very slightly (< 1%) due to current
sourcing in the game card. But they should be essentially independent,
for all reasonable values of potentiometers. Perhaps you need higher
quality components?

---Jim

http://www.oz.net/~wottenad/photogal.htm#hawnt

Best of luck, enjoy.

Dave Hawnt (UK)

........"GP2 rules, OK!"

Wally's designs do not work for the likes of F1RS - they use two pots - one
for brake and another for the accelerator. My design (inspired by Wally's)
is compatible with just about everything and has either one or two pots.

I need an artist to draw the pictures - or someone with a scanner to scan
pictures, then I will post the whole thing to a web site. Otherwise.... :-(

My design also looks far more like the "real thing" and is more compact.
Credit to Wally for starting me off in the first place though. His SW rocks
(if you can get the bits).

Mark

If anyone fancies experimenting, I have found that the cheap
photo-darlington "MEL12" may make a good optical "pot" replacement. The
trick will be making a adjustable gate to allow a given amount of light for
the control setting. Such a system is far less prone to jitter than the
typical home rig. A BPX25 will work the same - but it costs about twice as
much.

Simply connect the collector to the 5V pin and the emitter to the analog
input - just as if you are connecting a pot: but the polarity is important.
Note: the base is not used and may be removed.

If anyone knows the rated output from a typical game card (i.e. if it can
drive an IR LED) I'd love to hear from them: I don't fancy blowing my AWE64!
My experiment is currently using light from a simple torch; although room
lighting will suffice to test the theory. Range is from 8 at full
illumination (short circuit in effect) to 512 low-light ----> 0 (full
darkness =  not connected).

The point to all this is home made rigs seem to stress the pots greatly.
Mine are already showing signs of wear after a matter of months. A
solid-state system such as this would never wear out, should be more linear
(or at least, predictable) and far more reliable.

MTBF should only be dependant on the light source: 100 of 1000s of hours for
an LED I guess; far less for an incadescent source of course.

Comments...?

Microsoft Pro 3D (for example) uses optical "pots".

But it uses an internal processor to 'fake' std joystick output.

// Anders

I built a pedal system using two pots. One for brake, one for
accelerator.   Inspired by Wally but designed by me.  (Wally's wiring
diagram was used)  It works PERFECTLY in F1RS.  When the pots are wired
in series they appear to the game as a single resistive element on a
single joystick axis.

My point exactly - and you have to wire the pots back to back - not just in
series. In other words, so that the combined resistance is increased by one
pedal and decreased by the other. Wally's wiring will not work as is: it
assumes the sim reads TWO inputs as does GP2, Indy Car 2 and Fatal Racing I
think also. They assumed, I guess, that people had steering wheels and
pedals that act like joysticks (two axis) rather than the more expensive
triple or quad axis design (latter includes clutch!).

I have also figured a way to get 8 fire buttons without much extra hardware:
now how do I get the darn machine to read them!?? How's it done? Binary.
Four buttons = four bits... think about it for a moment and you'll see why
you can only use three inputs for this (8 combinations) and not four giving
16 buttons.

Mark

Right.  They use photochoppers, not analog techniques......

Hi again  :-)

I don't want to argue, and I understand what you're saying but.....

I don't think you should label Wally's wiring diagram as being
incorrect.  If you look in his pedal section and follow the link to
drawing, in the Pedal section, you will see two pots wired in series.
Below that you will see an explanation of the resistances you should
achieve in the finished product.  It mentions that as you depress the
brake, the series resistance should be reduced and when you depress the
accelerator the series resistance should be increased.  When you look at
his photos you will notice that when depressing the brake the pot will
turn in a counterclockwise direction(reducing resistance) and when
depressing the throttle it will rotate clockwise (resistance
increases).  The two pots are wired, in series, between pins 6 and 8 on
the DB15 connector, the Joystick 1 Y-axis input.  This does work, at
least with GP2, N2, F1RS, TOCA, Motoracer,Sega Touring Cars, and every
other driving sim I've tried my wheel on.

Wally also makes mention of another wiring scheme in his article.  This,
i assume, is what you are referring to when you mention trible or quad
axis designs.  These are not necessary for GP2....I can't comment on
Fatal Racing I.

Good luck getting your games to read eight buttons  :-)

On Thu, 26 Feb 1998 11:07:29 -0400, Rob Edsall

I took my sidewinder apart a few weeks ago to see if I could use the
bits on a homemade wheel.
There is one sensor on the main PCB below the centre of the stick, 2
LEDs on the bottom of the stick and 1 LED on the end of the throttle
arm. No choppers in sight - I was suprised!
My guess is that it uses some pretty fancy algorithm to determine
relative position of the leds and sensor. The sensor has to detect the
x, y and rudder axis from the position of just 2 LEDs.
Very neat and probably a lot more reliable than a slotted wheel.

If anyone knows any more details I would like to know.

I would also be very interested if anyone has built an optical pot for
a stick or wheel. (costing less that the comercial ones :-)

BTW. If you want to take your stick apart there is a***under both
front feet and under the silver label. I only discovered this after a
lot of swearing.

Toby
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