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View Full Version : Hey smart guys. Couple tough questions. .??



Gravit8
26-10-2015, 04:18
1. Does the BAC Mono have any electronic aids in real life?
Can't find any info on their website or the wiki page.

2. What does "Center negative" mean when it comes to break pedal calibration.

Sankyo
26-10-2015, 07:26
2) AFAIK this describes the sign of the signal that comes from the pedal. Any specific reason why you would like our need to know this?

Invincible
26-10-2015, 07:50
1. Does the BAC Mono have any electronic aids in real life?
Can't find any info on their website or the wiki page.


No, it doesn't. No TC, no ABS, no SC. I've read that in several articles now and seen in a video with Tim Schrick, where he tested the BAC Mono.

Timmynator
26-10-2015, 08:01
2. What does "Center negative" mean when it comes to break pedal calibration.

From my experience with a broken load cell it's an indicator of the pedal rest position:

"Positive" is when the pedal is "pushed out" at rest, i.e. you have to push it "in" (away from you) to increase the associated value
"Negative" would then be the opposite, e.g. the rest position of the pedal would be fully depressed and you'd have to "pull" on it to increase the value. Doesn't make sense for cars but a negative rest position might make sense for other applications like flight simulators and other joystick controls.

Schnizz58
26-10-2015, 17:52
The only time I've heard the term "center negative" is with respect to DC adaptors.

https://upload.wikimedia.org/wikipedia/commons/thumb/8/8f/Centre-negative.svg/220px-Centre-negative.svg.png

Gravit8
26-10-2015, 20:11
The only time I've heard the term "center negative" is with respect to DC adaptors.

https://upload.wikimedia.org/wikipedia/commons/thumb/8/8f/Centre-negative.svg/220px-Centre-negative.svg.png


My base pedals that came with t300 register as center negative when calibrating my pedals.

Beatminister
26-10-2015, 21:11
So do the T3PA-Pro.
But it works, thats the main thing.

Gravit8
26-10-2015, 22:17
So do the T3PA-Pro.
But it works, thats the main thing.

Yeah, but what does it mean? And how and why would a different pedal set register something different?

My pedals register as center negative before a number value is even picked up. Then the numbers move from1-100

Gravit8
26-10-2015, 22:21
2) AFAIK this describes the sign of the signal that comes from the pedal. Any specific reason why you would like our need to know this?

Just curiosity. Trying to understand the unknown
Plus I hate my pedals, so.....
Trying to understand how they work and differences I might find in other sets.

TwilightUA
26-10-2015, 22:44
2. Center negative means that your potentiometer (which you operate by pressing your pedal) is used lock to lock, so potential between a voltage divider and one of 2 terminals vary between 0 and 100% of voltage between 2 terminals. It means that your PC interprets "0%" as -axis maxed, "50%" as 0 and "100%" as +axis maxed. So your pedal travels from maxed -axis to +axis.

While Zero center means that you use your potentiometer only at 50%, means your PC sees pedal travel from 0 to +axis (or -, depends on polarity on potentiometer)

Woah, I'm good at english, but if I write about technical stuff, it seems so bad. Hope this text is understandable.

Gravit8
27-10-2015, 01:57
2. Center negative means that your potentiometer (which you operate by pressing your pedal) is used lock to lock, so potential between a voltage divider and one of 2 terminals vary between 0 and 100% of voltage between 2 terminals. It means that your PC interprets "0%" as -axis maxed, "50%" as 0 and "100%" as +axis maxed. So your pedal travels from maxed -axis to +axis.

While Zero center means that you use your potentiometer only at 50%, means your PC sees pedal travel from 0 to +axis (or -, depends on polarity on potentiometer)

Woah, I'm good at english, but if I write about technical stuff, it seems so bad. Hope this text is understandable.

Oh. Ok.
center negative means there's two polarity's essentially? Hence the two values and zeros at center and positive and negative values.

Zero center would mean a constant voltage/polarity. And a more straight forward 0-100 scale?

Still curious why the setup is used as opposed to a straight scale all the time.
Is there a difference in the end result with each type?

TwilightUA
27-10-2015, 12:55
Oh. Ok.
center negative means there's two polarity's essentially? Hence the two values and zeros at center and positive and negative values.

Not quite. http://s.eeweb.com/resized/images/remote/http_s.eeweb.com/quizzes/2011/4/27/potentiometer-construction-1317165052_500_344.png
Let's say voltage between A and B is 5V, so voltage between A and W vary from 0 to 5V. So 0-2.5V is negative axis and 2.5-5V is positive, 2.5v is zero


Zero center would mean a constant voltage/polarity. And a more straight forward 0-100 scale?


Zero center is 2.5 to 5V in example above. (or 0 to 2.5V)



Still curious why the setup is used as opposed to a straight scale all the time.
Is there a difference in the end result with each type?

Gamepads always use zero center, so does cheap pedals, where 2 pedals are on 1 axis (you can't use brake and throttle at the same time).

Gravit8
27-10-2015, 20:31
Not quite. http://s.eeweb.com/resized/images/remote/http_s.eeweb.com/quizzes/2011/4/27/potentiometer-construction-1317165052_500_344.png
Let's say voltage between A and B is 5V, so voltage between A and W vary from 0 to 5V. So 0-2.5V is negative axis and 2.5-5V is positive, 2.5v is zero


Zero center is 2.5 to 5V in example above. (or 0 to 2.5V)




Gamepads always use zero center, so does cheap pedals, where 2 pedals are on 1 axis (you can't use brake and throttle at the same time).

Ok thanks. I get the center negative, not how two pedals would end up on the same axis as two different inputs?
But we probably don't have time to discuss every question this will bring up. Haha. Thanks again for your explanation.

TwilightUA
27-10-2015, 21:37
how two pedals would end up on the same axis as two different inputs?

220930

There is a scheme of my pedals (before I modified them)

Two same resistors are used lock-to-lock. Voltage between "+" and "-" is 5V. According to Kirchhoff's 2nd law 2.5V drops on R1 and 2.5V on R2 (because they are the same).
1)Potential between "+" and "W" is 2.5V, which is "zero" to your PC.
2) If you press pedal with resistor R1, it's resistance becomes 0 Ohm, potential between "+" and "W" drops to 0V, which is negative axis.
3) If you press pedal with resistor R2, it's resistance becomes 0 Ohm, potential between "+" and "W" increases to 5V, which is positive axis.


Thanks again for your explanation.

My pleasure.

Gravit8
28-10-2015, 04:29
220930

There is a scheme of my pedals (before I modified them)

Two same resistors are used lock-to-lock. Voltage between "+" and "-" is 5V. According to Kirchhoff's 2nd law 2.5V drops on R1 and 2.5V on R2 (because they are the same).
1)Potential between "+" and "W" is 2.5V, which is "zero" to your PC.
2) If you press pedal with resistor R1, it's resistance becomes 0 Ohm, potential between "+" and "W" drops to 0V, which is negative axis.
3) If you press pedal with resistor R2, it's resistance becomes 0 Ohm, potential between "+" and "W" increases to 5V, which is positive axis.



My pleasure.

Ok. Took me a while to process and wrap my head around. I'll have a Google to read up more on potentiometers.

If I understand this correctly. Modding my potentiometer or replacing is a good way to get a different feel out of set of pedals.
And why I imagine you know this in first place. ��. ;)
I also get why mine are so non reactive at initial travel. That zero needs to be reached at 2.5 before any further input is recognized as actual brake input? And why I hate my pedals so much.
They honestly feel like I push them at 10 to 20% of their travel distance before I get anything from them. I can honestly bounce up and down like crazy on them and get nothing in a small window that should be trailbraking
And then the breaking comes on hard and fast

Having read further on Internet. I am reasonably confident that my problem is linkage attached to the potentiometer
what I'm feeling is the linkage travel before the potentiometer gauges which is pretty crappy on a set of pedals.

Thanks again

Must get new pedals.

Or mod them with cardboard to get rid of mechanical play. Haha. Trying this tonight.

It worked nicely.

TwilightUA
28-10-2015, 11:35
I should point out that 5V between "+" and "-" is more like my speculation based on fact that USB output is 5V. It can be less. Means 2.5V as "zero" is not definitive statement. But principle remains the same.



They honestly feel like I push them at 10 to 20% of their travel distance before I get anything from them.


I went on cheap way to add 1 more axis (to be able to use brake and throttle at the same time) using gamepad as a donor. Long story short pedal, connected to wheel, has huge deadzone (like yours) ~15%, but pedal, connected to gamepad has almost no deadzone at all, and I used the same potentiometer. I want to say that it can be a software problem, or analog-to-digital convertor problem, or, who knows, bad potentiometers (which I slightly doubt).

FACT0RY PIL0T
28-10-2015, 12:18
Ok. Took me a while to process and wrap my head around. I'll have a Google to read up more on potentiometers.

If I understand this correctly. Modding my potentiometer or replacing is a good way to get a different feel out of set of pedals.
And why I imagine you know this in first place. ��. ;)
I also get why mine are so non reactive at initial travel. That zero needs to be reached at 2.5 before any further input is recognized as actual brake input? And why I hate my pedals so much.
They honestly feel like I push them at 10 to 20% of their travel distance before I get anything from them. I can honestly bounce up and down like crazy on them and get nothing in a small window that should be trailbraking
And then the breaking comes on hard and fast

Having read further on Internet. I am reasonably confident that my problem is linkage attached to the potentiometer
what I'm feeling is the linkage travel before the potentiometer gauges which is pretty crappy on a set of pedals.

Thanks again

Must get new pedals.

Or mod them with cardboard to get rid of mechanical play. Haha. Trying this tonight.

It worked nicely.

What kind of pedals? If there Fanatec's there use to be like 4 diffrent firmwares you could run to make them more or less sensitive.

Gravit8
28-10-2015, 22:20
I think it was mechanical play in the mechanism providing leverage to the pot.
Put a piece of cardboard in there to dial out the slop and bam, I have reactive pedals from the start.

Don't really see a need to tear them apart until later when they get replaced maybe.
Certainly a lot better for now.