# Modify potentiometer signal to 0-5k



## Yabert (Feb 7, 2010)

Hi

A quick question!
How I can modify a potentiometer signal from 1-2k to 0-5k? Is it possible?

I explain to you my situation...
In my Smart Fortwo, the accelerator come with a nicely integrated potentiometer. I would prefer use this potentiometer to drive my Kelly controller, but this one give an accurate 1k to 2k signal.

The Kelly KDHD controller accept two wires 0-5k and hall effect signal.
Is it possible to control the controller with the Smart potentiometer?

Thanks


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## rwaudio (May 22, 2008)

The Solitons let you configure the "range" of pedal travel, meaning that what the controller considers 0 and full throttle don't have to be 0 ohms and 5k ohms exactly. Perhaps the Kelly lets you configure the range as well and you could use the existing pedal without having to add anything to the circuit that might compromise reliability.
Worth a look in the software anyways.
Good luck.


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## Yabert (Feb 7, 2010)

I open the potentiometer to see if I can change some parts... the answer seem be NO!

I try to set the throttle effective starting position of my controller to 20%, but it don't work. I need to retry!
But, anyway, if I can set the starting position of the 0-5k to 20% (1k), I can't set the ending position bellow 60% (3k), so I will lose 33% of throttle (power).
Someone have good idea?

Thanks


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## rwaudio (May 22, 2008)

Are there seperate (independant) resistive sections on the board? It looks like there are multiple wipers. If there are and they are all in the 1k range you could wire a few of them in series which would give you 2-4k.
Might be close enough to work.

What happens if you measure between different wires?




Yabert said:


> I open the potentiometer to see if I can change some parts... the answer seem be NO!
> 
> I try to set the throttle effective starting position of my controller to 20%, but it don't work. I need to retry!
> But, anyway, if I can set the starting position of the 0-5k to 20% (1k), I can't set the ending position bellow 60% (3k), so I will lose 33% of throttle (power).
> ...


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## Yabert (Feb 7, 2010)

rwaudio said:


> The Solitons let you configure the "range" of pedal travel, meaning that what the controller considers 0 and full throttle don't have to be 0 ohms and 5k ohms exactly.


Yes, Kelly too. Thanks. But I can set the controller at his max range of 40% and 60% (2-3k).
So, with 1k resistor I modified my 1-2k to 2-3k, but because 2-3k is the extreme limit range of the controller, that don't work.
The problems is than the pot is more like 1.015k to 1.975k.

So, I try some resistance combo to clear the fault of the controller and it's finally works.
But the controller set at 2-3k seem worked from 1.930k (over this, it claim a fault) and because the pot give only 0.960k, the maximum signal will be 2.890k.

And because of 1k = 1000A, I will have acces to only 890A from my controller. 
Lose 11% of power cause of this nice potentiometer isn't a good solution!


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## Woodsmith (Jun 5, 2008)

I had to modify my Land Rover throttle pot for the tractor. It had several outputs, non of which were right. Made it right in the end though.
1st post
2nd post


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## Yabert (Feb 7, 2010)

So, after few tests with this 1-2K potentiometer, the conclusion is:

-I can reduce the signal when I mix some wire (0.3-0.8K).
-I can have a 1.2-2.2K signal with two other wires (same 1K range).
-I can shift (gap) the signal with resistor (2-3K with 1K resistor).

And the real question is: How I can increase the signal (1-3K)?????
Is it possible??

Thanks!


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## rwaudio (May 22, 2008)

Yabert said:


> So, after few tests with this 1-2K potentiometer, the conclusion is:
> 
> -I can reduce the signal when I mix some wire (0.3-0.8K).
> -I can have a 1.2-2.2K signal with two other wires (same 1K range).
> ...


Do you have more than one 1k signal?


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## piotrsko (Dec 9, 2007)

500 to 1K ohm resistor paralleling the F1 output for low,(resistance in parallel is <1/2 the lowest resistance of the pair), a 1K resistor across the wiper lead in series for the upper end. With the parallel resistance you will need a larger series resistance, perhaps as much as 100K. Sorry my theory is kinda rusty any more.

or if the other leads work in the same direction just wire those in series with the parallel potentiometer resistance across the output and tweak until happy.

might end up being VERY sensitive due to the parallel resistor

I see in the pictures that you have multiple resistance paths, so.... series a couple or two and parallel one. still think it might be too twitchy.


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## Jimdear2 (Oct 12, 2008)

Yabert said:


> I open the potentiometer to see if I can change some parts... the answer seem be NO!
> 
> I try to set the throttle effective starting position of my controller to 20%, but it don't work. I need to retry!
> But, anyway, if I can set the starting position of the 0-5k to 20% (1k), I can't set the ending position bellow 60% (3k), so I will lose 33% of throttle (power).
> ...


Yabert,

Just a thought.

Have you searched for an off the shelf 0 to 5 K ohm resistor that could be fitted inside this housing if you were to gut it?

Maybe there is something a simple fix out there.

Jim


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## Yabert (Feb 7, 2010)

> Do you have more than one 1k signal?


Yes!
If you watch my picture, two wires (violet and grey/yellow) give to me 1.015K to 1.980K and two other wires (green and white/yellow) give to me 0.915K to 1.940K.

I have some resistor with me (100K, 1.5K, 1K, 0.3K)!

What I can do to increase the resistive signal from my pot?


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## rwaudio (May 22, 2008)

Yabert said:


> Yes!
> If you watch my picture, two wires (violet and grey/yellow) give to me 1.015K to 1.980K and two other wires (green and white/yellow) give to me 0.915K to 1.940K.
> 
> I have some resistor with me (100K, 1.5K, 1K, 0.3K)!
> ...


Put the two seperate resistor sections in series then you will have a ~2k to ~4k resistance which might be a wide enough range to make the controller happy.

IE: connect grey/yellow to green and measure from violet to white/yellow, or connect grey/yellow to white/yellow and measure violet to green, one of those combinations should work.


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## Yabert (Feb 7, 2010)

Thank a lot.

Apparently it was one of many possible combination that I did not try.

The result is an exellent range of 1.925K to 3.940K ... So perfect for my controller adjusted 40% and 78% of the 0-5K range.

I'm really happy! The original potentiometer in the accelerator pedal of the diesel Smart will work perfectly for the electric Smart...


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## rwaudio (May 22, 2008)

Yabert said:


> Thank a lot.
> 
> Apparently it was one of many possible combination that I did not try.
> 
> ...


Glad it works, it's always better when you can repurpose the stock parts.


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