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Re: [EVDL] Jumpy Pots

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#1 ·
Re: [EVDL] Jumpy Pots

I've had the same Curtis pot box in my EV for at least 3 years,
possibly up to 14 years old (I bought the car previously converted and
used). Currently my pot box is inside a weatherproof enclosure:

http://picasaweb.google.com/lh/photo/sby8m0mJDgKUTfUMTvYoVA?feat=3Ddirectli=
nk

it still works smoothly for me on a Kodiak controller

-Jon Glauser
http://jonglauser.blogspot.com
http://www.evalbum.com/555



soundboats <xxx@xxx.xxx.gov> wrote:
>
> Hello, I am trying to find out if anyone has had any luck in finding
> potentiometers that do not degrade with heavy use. I have tried the Cu=
rtis
> PB-6, a Chinese copy of the PB-6, and the Logisystem potboxes. All have
> suffered from the same degradation over time and last no more than 6-8
> months in heavy city and suburban driving (about 100 miles a week in stop
> and go traffic). The Logisystems potbox lasted only 2 months, the Curt=
is
> about 8 months, and the Chinese copy has been in for 6 months and showing
> signs of degradation.
> Initially all the potentiometers have a steady increase in resistance with
> the movement of the arm. However, the pots become progressively =93jum=
py,=94
> making driving difficult. I have measured the resistance and find that=
any
> small movement of the arm makes the resistance go up much higher for seco=
nd
> and then come down to what it should be. For example, if I have the ar=
m in
> a position that provides 1000 Ohms of resistance and move it just a few
> degrees the resistance jumps to 2500 Ohms before coming back down to 1200
> Ohms. This type of jump occurs at any setting of the arm and is not re=
lated
> to the controller. I have measured this jump when the pot boxes are
> disconnected from the controller as well.
> So, I am trying to find out if there is a brand of potentiometers that do
> not have this problem. I have found out that the resistance in these p=
ots
> is provided by a piecce of plastic, and I wonder if the plastic degrades
> with use. Any help would be welcome.
> Thanks,
> Tom Hruby
>
> --
> View this message in context: http://www.nabble.com/Jumpy-Pots-tp25648568=
p25648568.html
> Sent from the Electric Vehicle Discussion List mailing list archive at Na=
bble.com.
>
>
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>

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#52 ·
Re: [EVDL] Jumpy Pots

Smoking pot again, eh.


You cannot put pack (120V) voltage on a 5k pot as it will
burn up from the power dissipated in it.
Though I would expect that they typically use 12V to get
the reading from the throttle pot - or if the pack is
below 48V they may still use that directly...

Regards,

Cor van de Water


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#53 ·
Re: [EVDL] Jumpy Pots

Years ago I needed to retrofit a large analog system that had several potentiometers with a programmer to emulate different pot settings. I experimented with photoresistor/LED combinations in heat shrink housings piggybacked on the pots, but these were not very repeatable. Not only that, the photoresistors (from Radio Shack) tended to have light-history memory. What I ended up using were Vactecs:

http://users.rcn.com/oakridge.ma.ultranet/Products/Vactrol.html

These were very repeatable and predictable, and surprisingly fast. Of course for a pedal application, you would most likely drive the lamp with a voltage from a pot, which just brings us back to the original problem. However, I would think such a setup would nicely filter out scratchiness.

Best Regards,

- Gene



-----Original Message-----
From: xxx@xxx.xxx.edu [mailto:xxx@xxx.xxx.edu] On
Behalf Of soundboats
Sent: Thursday, October 01, 2009 1:27 AM
To: xxx@xxx.xxx.edu
Subject: Re: [EVDL] Jumpy Pots


Hello everyone who responded.
I am starting a new thread on this subject since it is getting very
confusing to follow who said what.
So I thought I would summarize some of the information I have gleaned
from this discussion and put it all in one place, and of course leave
you with more questions.

1. The basic problem seems to be that the standard potentiometers are
getting contaminated with dust or other debris, and sealing the box
would probably prevent the degradation. I will try this first since I
have replaced the potentiometer in the PB-6 box I have with one I
purchased from EVParts.

2. It might be possible to find a MIL spec pot (either carbon or plastic
based)that is sealed and meets the the resistance and "travel"
requirements for my throttle. These are rated at 25,000 cycles which
however does not really meet my needs. I did a simple calculation on my
lunch break and found that I cycle the throttle/pot about 10 times per
mile in the city driving I do. This means the pot would be rated for
only 2500 miles or about 8 months of my driving.

3. It is possible to find a pot from a electric fork lift that is rated
much higher, but it costs about $75. I have not tried to do this yet.

4. Some of you have suggest Hall effect potentiometers. I looked into
them but found that they are rated only for 4-5 volts inputs. I believe
both the Curtis and Logisystem controllers put out the full battery pack
voltage to the pot (120 volts in my case). Only the Kelly's put out 5
volts to the pot.
If anyone out there knows more about this please let us all know!!! It
would be interesting to try a Hall effect pot.

Tom Hruby


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#54 ·
Re: [EVDL] Jumpy Pots

On 30 Sep 2009 at 16:24, Gene Stopp wrote:

> What I ended up using were Vactecs:
>
> http://users.rcn.com/oakridge.ma.ultranet/Products/Vactrol.html
>
> These were very repeatable and predictable, and surprisingly fast. Of course
> for a pedal application, you would most likely drive the lamp with a voltage
> from a pot, which just brings us back to the original problem. However, I
> would think such a setup would nicely filter out scratchiness.

That's exactly the sort of solution I suggested the last time we had this
discussion on the EVDL.

Over 30 years ago, I used audio consoles in which the faders were based on
this idea. The dirt-cheap potentiometers on the console actually controlled
the brightness of incandescent lamps, which shone on CdS cells (LDRs). They
were made by Sparta, IIRC.

They turned oiut to be major headaches for the audio engineers. It was
almost impossible to keep the stereo channels in balance over the entire
range of the fader. This pretty clearly shows the inherent stability
problem.

However, I don't think that would matter very much for an EV controller.
The only problem I can see is if the lamp were to burn out. You'd need a
resistance-limiting safeguard to make sure the controller wouldn't go full
speed ahead in that instance. (The lamps in the Sparta consoles almost
never failed, btw; they were run well below their rated voltage.)

David Roden - Akron, Ohio, USA
EVDL Administrator

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#55 ·
Re: [EVDL] Jumpy Pots

soundboats wrote:
> 1. The basic problem seems to be that the standard potentiometers are
> getting contaminated with dust or other debris, and sealing the box would
> probably prevent the degradation. I will try this first since I have
> replaced the potentiometer in the PB-6 box I have with one I purchased from
> EVParts.

A good idea, given that you already have the pot. But the fundamental
problem is caused by a cheap unsealed pot. Sealing up the potbox will
help, but it won't retrofit quality into a cheap pot.

> 2. It might be possible to find a MIL spec pot (either carbon or
> plastic based) that is sealed and meets the the resistance and
> "travel" requirements for my throttle. These are rated at 25,000
> cycles which however does not really meet my needs.

The one I mentioned is just one I used that's better than the original.
It's not the "ideal" solution, developed from an exhaustive analysis and
search. It's just the first one I found that was better than what I had.

You can buy pots with arbitrarily good specs. The ones used in mass
produced cars are certainly better than what I used -- but they are hard
to buy in single-piece quantities without the ridiculous mark-ups (a ten
cent bolt from the hardware store costs $10 at your auto dealer).

So, do your own research. The electronics distributors have literally
hundreds of pots to choose from. Look up their specifications until you
find one with good enough specs to satisfy you. The better the pot, the
higher the price, of course.

> 3. It is possible to find a pot from a electric fork lift that is
> rated much higher, but it costs about $75.

I'll bet you'll find that inside that $75 forklift potbox is a $5 or $10
pot from the Digikey or Mouser catalogs.

> 4. Some of you have suggest Hall effect potentiometers. I looked into them
> but found that they are rated only for 4-5 volts inputs.

Hall effect sensors are a good solution if you're designing the
controller to match. But they are hard to retrofit onto a controller
that was designed for a resistive potentiometer.

--
Lee A. Hart | Ring the bells that still can ring
814 8th Ave N | Forget the perfect offering
Sartell MN 56377 | There is a crack in everything
leeahart earthlink.net | That's how the light gets in -- Leonard Cohen

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#56 ·
Re: [EVDL] Jumpy Pots

I have the impression that with the pedal pot driving a Vactec
you are using too many parts and still have the problem of the
"worn through spot" on the pedal pot where you spend most of
the time (unless you are one of the ON/OFF type drivers)
Anyhow, the incandescent lamp and CdS setup is exactly what
is needed - plus a moving vane in between, so that the light
from the lamp can be extinguished by the vane and the value
of the CdS cell controlled from min to max resistance.
Looking at the Vactrol VTLA37 resistance/time graph I see
that it reaches less than 200 and over 10kOhm within 100ms
after application of Full on/off lamp brightness, so I would
venture a guess that adding a vane in between might increase
the ON resistance slightly (more distance between lamp/cell)
but we only need to be <500 Ohm for a throttle pot.
To limit the max resistance simply add a fixed 4.7kOhm in
parallel to the CdS cell, however it may be preferable to
never allow the vane to completely block the light and keep
the CdS below 5kOhm with the remaining lamp light, so that
if the lamp dies (or the CdS cell) then the resistance is
above 5k and the controller will fault, instead of possibly
going full throttle. (depending if 5k is low or high throttle)

So, this brings us back to a suggestion already made before...
NOTE that the vane and the Vactec (or discrete lamp + CdS cell)
must be shielded from ambient light, otherwise you will only
be able to drive at night!
I think I have seen this type of control in some instruments
in the past, I think it was in some old electronic organs and
in sewing machine foot pedals in conjunction with a TRIAC.

Cor van de Water
Director HW & Systems Architecture Group Proxim Wireless
Corporation http://www.proxim.com
Email: xxx@xxx.xxx Private: http://www.cvandewater.com
Skype: cor_van_de_water IM: xxx@xxx.xxx
Tel: +1 408 383 7626 VoIP: +31 20 3987567 FWD# 25925
Tel: +91 (040)23117400 x203 XoIP: +31877841130

-----Original Message-----
From: xxx@xxx.xxx.edu [mailto:xxx@xxx.xxx.edu] On
Behalf Of Gene Stopp
Sent: Thursday, October 01, 2009 4:54 AM
To: Electric Vehicle Discussion List
Subject: Re: [EVDL] Jumpy Pots

Years ago I needed to retrofit a large analog system that had several
potentiometers with a programmer to emulate different pot settings. I
experimented with photoresistor/LED combinations in heat shrink housings
piggybacked on the pots, but these were not very repeatable. Not only
that, the photoresistors (from Radio Shack) tended to have light-history
memory. What I ended up using were Vactecs:

http://users.rcn.com/oakridge.ma.ultranet/Products/Vactrol.html

These were very repeatable and predictable, and surprisingly fast. Of
course for a pedal application, you would most likely drive the lamp
with a voltage from a pot, which just brings us back to the original
problem. However, I would think such a setup would nicely filter out
scratchiness.

Best Regards,

- Gene



-----Original Message-----
From: xxx@xxx.xxx.edu [mailto:xxx@xxx.xxx.edu] On
Behalf Of soundboats
Sent: Thursday, October 01, 2009 1:27 AM
To: xxx@xxx.xxx.edu
Subject: Re: [EVDL] Jumpy Pots


Hello everyone who responded.
I am starting a new thread on this subject since it is getting very
confusing to follow who said what.
So I thought I would summarize some of the information I have gleaned
from this discussion and put it all in one place, and of course leave
you with more questions.

1. The basic problem seems to be that the standard potentiometers are
getting contaminated with dust or other debris, and sealing the box
would probably prevent the degradation. I will try this first since I
have replaced the potentiometer in the PB-6 box I have with one I
purchased from EVParts.

2. It might be possible to find a MIL spec pot (either carbon or plastic
based)that is sealed and meets the the resistance and "travel"
requirements for my throttle. These are rated at 25,000 cycles which
however does not really meet my needs. I did a simple calculation on my
lunch break and found that I cycle the throttle/pot about 10 times per
mile in the city driving I do. This means the pot would be rated for
only 2500 miles or about 8 months of my driving.

3. It is possible to find a pot from a electric fork lift that is rated
much higher, but it costs about $75. I have not tried to do this yet.

4. Some of you have suggest Hall effect potentiometers. I looked into
them but found that they are rated only for 4-5 volts inputs. I believe
both the Curtis and Logisystem controllers put out the full battery pack
voltage to the pot (120 volts in my case). Only the Kelly's put out 5
volts to the pot.
If anyone out there knows more about this please let us all know!!! It
would be interesting to try a Hall effect pot.

Tom Hruby


_______________________________________________
General EVDL support: http://evdl.org/help/ Usage guidelines:
http://evdl.org/help/index.html#conv
Archives: http://evdl.org/archive/
Subscription options: http://lists.sjsu.edu/mailman/listinfo/ev


_______________________________________________
General EVDL support: http://evdl.org/help/
Usage guidelines: http://evdl.org/help/index.html#conv
Archives: http://evdl.org/archive/
Subscription options: http://lists.sjsu.edu/mailman/listinfo/ev
 
#57 ·
Re: [EVDL] Jumpy Pots

This post by Tom exactly describes the symptoms my PB6 is displaying. It
started a few weeks ago and is getting worse. The car has about 8 months on
it, same as when Tom's started acting up. Anyone found a better solution
than the PB6? The controller is a Curtis 1238-7501.
--
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#58 ·
Re: [EVDL] Jumpy Pots

I've recently had a problem in my conversion which I thought might be jumpy
pots also. It turns out (I think) that it was a symptom of the 12V battery
dying. Since that battery keeps the contactor closed, things could
obviously get weird when it was starting to be at a threshold voltage.
After dropping further, the 12V battery got to the point it wouldn't keep
the contactor open and the car stopped.

The conversion had previously been using a separate 12V charger that I think
has died. It is now time to bump up the DC-DC converter installation in
priority.

My symptom was a surging and jerking under acceleration. Now, I think it
was because the contactor was briefly cutting out.

Mike

-----Original Message-----
From: xxx@xxx.xxx.edu [mailto:xxx@xxx.xxx.edu] On Behalf
Of tomw
Sent: Sunday, August 22, 2010 7:21 PM
To: xxx@xxx.xxx.edu
Subject: Re: [EVDL] Jumpy Pots


This post by Tom exactly describes the symptoms my PB6 is displaying. It
started a few weeks ago and is getting worse. The car has about 8 months on
it, same as when Tom's started acting up. Anyone found a better solution
than the PB6? The controller is a Curtis 1238-7501.
--
View this message in context:
http://electric-vehicle-discussion-list.413529.n4.nabble.com/Jumpy-Pots-tp46
2965p2334529.html
Sent from the Electric Vehicle Discussion List mailing list archive at
Nabble.com.

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#59 ·
Re: [EVDL] Jumpy Pots

Thanks Wistar, I will see if I can get a replacement. Thanks also to Bill
and Mike. I will keep those possibilities in mind. I found that EVWorks
offers a Hall Effect throttle that is a bolt in replacement for the PB6. It
appears this would work for my car as I can reprogram the controller to use
this "type 2" throttle. I also found a Honeywell/Clarion industrial pot
(#380C325K) at Digikey with 100,000 cycle rotational life. It is a 312
degree pot, and my PB6 looks to be about 45 degree. A 25k version would
then give about 3.6V max voltage, and the max voltage setpoint in the
controller software currently is 3.5V, so that seems about right. The Hall
Effect is a better long term solution, and it appears I can do it with
existing wiring in the harness, just switching connection on one wire to get
a ground, and adding in a 5V regulator at the throttle pot powered off the
12V to the microswitch. Some details to work out though, like current
requirements.
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#60 ·
Re: [EVDL] Jumpy Pots

Hello to another Tom,

Sorry to be so late in responding, but I just got back from vacation.

I found that the Chinese copy of the PB-6 that is available from several
vendors has worked out better than the PB-6. I also tried the
replacement pot that is sold by EV-parts, but that proved to be bad from
the beginning. The discussion around my first comments suggested that
the issue was dirt getting into the box. I taped my Chinese copy around
all the open edges and that seems to have improved the situation. My
Chinese copy has now been installed for over a year without any
problems. However, I do suspect that it may go soon. It is showing
some instability when the outside temperature goes above 90 degrees.



My Logisystems controller blew out for the second time and so I am now
switching and will try the NetGain controller that has the Hall effect
throttle. I hope that works out better.



Tom



From: tomw [via Electric Vehicle Discussion List]
[mailto:ml-node+xxx@xxx.xxxle.com]
Sent: Sunday, August 22, 2010 6:21 PM
To: Hruby, Tom (ECY)
Subject: Re: Jumpy Pots



This post by Tom exactly describes the symptoms my PB6 is displaying.
It started a few weeks ago and is getting worse. The car has about 8
months on it, same as when Tom's started acting up. Anyone found a
better solution than the PB6? The controller is a Curtis 1238-7501.

________________________________

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#61 ·
Re: [EVDL] Jumpy Pots

My third pot from Kelly is now failing. It's an enclosed foot pedal and the
pot is a sealed Hoss WDJ 22 and doesn't feel like a cheapo, but three of
them have failed within less than a month each. The spec sheet I found
seems to show values of rotation from 20K to 100K cycles, but that's not
much in automotive use considering how often a throttle is moved during a
drive. Automotive pots seem to list millions of cycles, I just can't seem
to find one with a male shaft that will fit inside the Kelly pedal assembly.


Tom H wrote:
>
> Hello to another Tom,
>
> Sorry to be so late in responding, but I just got back from vacation.
>
> I found that the Chinese copy of the PB-6 that is available from several
> vendors has worked out better than the PB-6. I also tried the
> replacement pot that is sold by EV-parts, but that proved to be bad from
> the beginning. The discussion around my first comments suggested that
> the issue was dirt getting into the box. I taped my Chinese copy around
> all the open edges and that seems to have improved the situation. My
> Chinese copy has now been installed for over a year without any
> problems. However, I do suspect that it may go soon. It is showing
> some instability when the outside temperature goes above 90 degrees.
>
>
>
> My Logisystems controller blew out for the second time and so I am now
> switching and will try the NetGain controller that has the Hall effect
> throttle. I hope that works out better.
>
>
>
> Tom
>
>
>
> From: tomw [via Electric Vehicle Discussion List]
> [mailto:ml-node+xxx@xxx.xxxle.com]
> Sent: Sunday, August 22, 2010 6:21 PM
> To: Hruby, Tom (ECY)
> Subject: Re: Jumpy Pots
>
>
>
> This post by Tom exactly describes the symptoms my PB6 is displaying.
> It started a few weeks ago and is getting worse. The car has about 8
> months on it, same as when Tom's started acting up. Anyone found a
> better solution than the PB6? The controller is a Curtis 1238-7501.
>
> ________________________________
>
> View message @
> http://electric-vehicle-discussion-list.413529.n4.nabble.com/Jumpy-Pots-
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>
>
>
>

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#62 ·
Re: [EVDL] Jumpy Pots

Hi Tom,

Yes, I've heard dust suspected as the cause, but mine is inside an aluminum
box, and the inside of the box appears clean. Could still be the cause if
it only takes a very small amount of dust I suppose. I can install the
EVWorks Hall throttle fairly easily it turns out. The controller has 5V and
ground outputs as well as the throttle input. I just have to switch two
wires and add one. The throttle pot will mount right in place of the PB6.
That way I shouldn't have to replace the throttle every year or two. As
JRP3 says even 100k cycles isn't all that much considering all the small
adjustments you are continuously making with the throttle for grade
changes, slowing/speeding up in traffic, changing speed limits,
stopping/starting... I do a lot of driving at about the same speed so that
part of the throttle gets a lot of use, and that is where the throttle is
jumpy. I should receive the Hall throttle in a few days or so.
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#63 ·
Re: [EVDL] Jumpy Pots

Has anybody ever tried one of these arcade game controllers?

http://www.happcontrols.com/driving/50819400.htm

I'm considering getting it for my electric rider mower. The price is mighty
reasonable, and one would hope that a pedal made for arcade use would be
pretty durable.

David Roden - Akron, Ohio, USA
EVDL Administrator

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#64 ·
Re: [EVDL] Jumpy Pots

*David, That is a difficult question to answer. Back in 1979, I was a video
game service tech. for Champeen (sic) Electronics and we repaired the big
consoles 6 ft tall, 2 ft wide, and 3 ft deep in a big plywood box. I built
one into a special case to hold a 60 in. monitor that was the "Showcase " of
the Arcade who bought it. Funny because it only ran "Asteroids" a monochrome
game. To your point the only pedals that lasted had a small incandescent
lamp running on 2/3 of rated voltage for longer life and a CdS photo cell
that provided varying resistance as light level changed, and a wire link
moved a moving vane between the lamp and the CdS cell as the pedal was
pressed about 2 inches the vane moved 1/4 inch These lasted for ever.
Everything else wore out after two years or less, I know, I replaced pots
and micro-switches constantly. My dream EV would use a slotted vane moving
between two led and two photo transistor and a up/down counter like a mouse
to drive a D to A conversion ladder that would be cheep and have no wear
parts. And more linear than a hall effect device. add a third led and photo
transistor to kick the counter to zero when the pedal is all the way up for
calibration.
Regards,
Dennis Lee Miles (Director) E.V.T.I. inc.
www.E-V-T-I-Inc.COM (Adviser) EVTI-EVA Education Chapter
Phone (863) 944 - 9913*
-------------------------------------------------------------------------------------------------------------------
EVDL Administrator <xxx@xxx.xxx>wrote:

> Has anybody ever tried one of these arcade game controllers?
>
> http://www.happcontrols.com/driving/50819400.htm
>
> I'm considering getting it for my electric rider mower. The price is
> mighty
> reasonable, and one would hope that a pedal made for arcade use would be
> pretty durable.
>
> David Roden - Akron, Ohio, USA
> EVDL Administrator
>
> = = = = = = = = = = = = = = = = = = = = = = = = = = = = =
> EVDL Information: http://www.evdl.org/help/
> = = = = = = = = = = = = = = = = = = = = = = = = = = = = =
> Note: mail sent to "evpost" an "etpost" addresses will not
> reach me. To send a private message, please obtain my
> email address from the webpage http://www.evdl.org/help/ .
> = = = = = = = = = = = = = = = = = = = = = = = = = = = = =
>
>
> _______________________________________________
> | REPLYING: address your message to xxx@xxx.xxx.edu only.
> | Multiple-address or CCed messages may be rejected.
> | UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub
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>
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#65 ·
Re: [EVDL] jumpy Pots

OK, found the old thread with the pot suggestion from Lee,
besides the obvious to go to pick-n-pull and get a TPS
(Throttle Position Sensor) from one of the cars that has
drive by wire (which is essentially all modern cars).
My car also accepts a 0 to 3.5V input instead of the
accelerator potmeter, so I can make things work even if they
are not 0-5kOhm...

I noticed an old request from someone to convert a 0 - 5V
signal to a 0 - 5kOhm resistance. That should be simple and
only require an opamp and two identical MOSFETs. Send a
fixed 1mA current through one and compare with the input
voltage. The other represents the 0 - 5kOhm output based on
the 0-5V input.
In case it needs to be 5k - 0 or other conversions
(for example from a too sensitive linear pot to logarithmic,
which will allow smooth take-off) then that is possible also.

Cor van de Water
Chief Scientist
Proxim Wireless Corporation http://www.proxim.com
Email: xxx@xxx.xxx Private: http://www.cvandewater.com
Skype: cor_van_de_water XoIP: +31877841130
Tel: +1 408 383 7626 Tel: +91 (040)23117400 x203

-----Original Message-----
From: xxx@xxx.xxx.edu [mailto:xxx@xxx.xxx.edu] On
Behalf Of Lee Hart
Sent: Tuesday, September 29, 2009 9:04 AM
To: Electric Vehicle Discussion List
Subject: Re: [EVDL] jumpy Pots

Electric Blue auto convertions wrote:
> I have only had 3 pots go bad so far and they were with in the first
> year. NOW if you see what Fork lifts use, the same thing only built
> much better and are still 5K ohm they last forever, BUT if you call
> Hyster, Cat, or Clark they want between 50 and 70 $ for the pot
> itself, is it worth it> thats up to you ..Wayne ev-blue.com

Try MIL style RV4. There are many manufacturers (like the Allen Bradley
type AB I mentioned, though Allen Bradley seems to have sold their pot
business to someone, so it's under a new name). Here's an example from
Digikey:

http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail&name=RV4N253
C-ND
http://www.precisionelectronics.com/MIL%20Style%20RV4%20PDF%20Download_f
iles/MIL%20Style%20RV4.pdf

Sealed, gold plated terminals, stainless steel shaft, 25,000 cycle
rotational life, about $8.
--
Lee A. Hart | Ring the bells that still can ring
814 8th Ave N | Forget the perfect offering
Sartell MN 56377 | There is a crack in everything
leeahart earthlink.net | That's how the light gets in -- Leonard Cohen

_______________________________________________
General EVDL support: http://evdl.org/help/ Usage guidelines:
http://evdl.org/help/index.html#conv
Archives: http://evdl.org/archive/
Subscription options: http://lists.sjsu.edu/mailman/listinfo/ev


_______________________________________________
| Moratorium on drag racing discussion is in effect.
| Please take those discussions elsewhere. Thanks.
|
| REPLYING: address your message to xxx@xxx.xxx.edu only.
| Multiple-address or CCed messages may be rejected.
| UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub
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#66 ·
Re: [EVDL] jumpy Pots

When ordering the pot, be very careful to determine the length of the shaft
and make sure it's compatible with the pot already in the potbox. My first
try, I got a pot that looked compatible, but the shaft was too short to fit
correctly into the lever arm.

Mike

> -----Original Message-----
> From: xxx@xxx.xxx.edu [mailto:xxx@xxx.xxx.edu] On
> Behalf Of Cor van de Water
> Sent: Wednesday, June 27, 2012 1:01 PM
> To: Electric Vehicle Discussion List
> Subject: Re: [EVDL] jumpy Pots
>
> OK, found the old thread with the pot suggestion from Lee, besides the
> obvious to go to pick-n-pull and get a TPS (Throttle Position Sensor) from
one
> of the cars that has drive by wire (which is essentially all modern cars).
> My car also accepts a 0 to 3.5V input instead of the accelerator potmeter,
so I
> can make things work even if they are not 0-5kOhm...
>
> I noticed an old request from someone to convert a 0 - 5V signal to a 0 -
> 5kOhm resistance. That should be simple and only require an opamp and two
> identical MOSFETs. Send a fixed 1mA current through one and compare with
> the input voltage. The other represents the 0 - 5kOhm output based on the
> 0-5V input.
> In case it needs to be 5k - 0 or other conversions (for example from a too
> sensitive linear pot to logarithmic, which will allow smooth take-off)
then
> that is possible also.
>
> Cor van de Water
> Chief Scientist
> Proxim Wireless Corporation http://www.proxim.com
> Email: xxx@xxx.xxx Private: http://www.cvandewater.com
> Skype: cor_van_de_water XoIP: +31877841130
> Tel: +1 408 383 7626 Tel: +91 (040)23117400 x203
>
> -----Original Message-----
> From: xxx@xxx.xxx.edu [mailto:xxx@xxx.xxx.edu] On
> Behalf Of Lee Hart
> Sent: Tuesday, September 29, 2009 9:04 AM
> To: Electric Vehicle Discussion List
> Subject: Re: [EVDL] jumpy Pots
>
> Electric Blue auto convertions wrote:
> > I have only had 3 pots go bad so far and they were with in the first
> > year. NOW if you see what Fork lifts use, the same thing only built
> > much better and are still 5K ohm they last forever, BUT if you call
> > Hyster, Cat, or Clark they want between 50 and 70 $ for the pot
> > itself, is it worth it> thats up to you ..Wayne ev-blue.com
>
> Try MIL style RV4. There are many manufacturers (like the Allen Bradley
type
> AB I mentioned, though Allen Bradley seems to have sold their pot business
> to someone, so it's under a new name). Here's an example from
> Digikey:
>
> http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail&name=RV4N25
> 3
> C-ND
> http://www.precisionelectronics.com/MIL%20Style%20RV4%20PDF%20Dow
> nload_f
> iles/MIL%20Style%20RV4.pdf
>
> Sealed, gold plated terminals, stainless steel shaft, 25,000 cycle
rotational life,
> about $8.
> --
> Lee A. Hart | Ring the bells that still can ring
> 814 8th Ave N | Forget the perfect offering
> Sartell MN 56377 | There is a crack in everything
> leeahart earthlink.net | That's how the light gets in -- Leonard
Cohen
>
> _______________________________________________
> General EVDL support: http://evdl.org/help/ Usage guidelines:
> http://evdl.org/help/index.html#conv
> Archives: http://evdl.org/archive/
> Subscription options: http://lists.sjsu.edu/mailman/listinfo/ev
>
>
> _______________________________________________
> | Moratorium on drag racing discussion is in effect.
> | Please take those discussions elsewhere. Thanks.
> |
> | REPLYING: address your message to xxx@xxx.xxx.edu only.
> | Multiple-address or CCed messages may be rejected.
> | UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub
> | OTHER HELP: http://evdl.org/help/
> | CONFIGURE: http://lists.sjsu.edu/mailman/listinfo/ev

_______________________________________________
| Moratorium on drag racing discussion is in effect.
| Please take those discussions elsewhere. Thanks.
|
| REPLYING: address your message to xxx@xxx.xxx.edu only.
| Multiple-address or CCed messages may be rejected.
| UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub
| OTHER HELP: http://evdl.org/help/
| CONFIGURE: http://lists.sjsu.edu/mailman/listinfo/ev
 
#67 ·
Re: [EVDL] jumpy Pots

My setup is not a standard potbox anyway.
It has the pot mounted in a bracket and on its shaft
is a metal piece with a set screw and a U-shaped hole.
In that hole sits a pin which can slide left and right
on another shaft. Next to that is also a metal block
which pushes the microswitch as soon as entire thing
starts sliding.
That contraption is not directly operated by the cable
from the pedal, but instead a lever is mounted where the
cable pulls on one end and the other end operates this
contraption, which also has return spring built-in.
It is a very universal and clever mechanical design,
but if you look at modern TPS assemblies attached to
the pedal itself, then you wonder why we make some
things so complex.
Same here - the whole deal with the microswitch selecting
between idle run and the pot, causing the controller to
throw errors when the input voltage goes over 3.7 during
the switch...
I was thinking about the whole deal and decided that the
simples solution is to send more current through the pot.
The upper 1.2 or 1.5kOhm is working well (little use) so
if I just increase the current by 2mA then the 3.6V to 0
range is the upper half of the pot.
To avoid that the input voltage goes too high and to
get a stable idle RPM, I will simply add a so-called
programmable zener like a TL431 and re-purpose the already
present trimpot and series resistor as the 2.5V divider
for the zener. This means that I can solder the TL431 on
that combination, add a pull-up resistor to send 2mA more
into the pot, remove the microswitch wires and simply
wire the zener in parallel to the pot and I am done.
I like it whem solutions are simple.

Cor van de Water
Chief Scientist
Proxim Wireless Corporation http://www.proxim.com
Email: xxx@xxx.xxx Private: http://www.cvandewater.com
Skype: cor_van_de_water XoIP: +31877841130
Tel: +1 408 383 7626 Tel: +91 (040)23117400 x203

-----Original Message-----
From: xxx@xxx.xxx.edu [mailto:xxx@xxx.xxx.edu] On
Behalf Of Mike Nickerson
Sent: Wednesday, June 27, 2012 10:39 PM
To: 'Electric Vehicle Discussion List'
Subject: Re: [EVDL] jumpy Pots

When ordering the pot, be very careful to determine the length of the
shaft and make sure it's compatible with the pot already in the potbox.
My first try, I got a pot that looked compatible, but the shaft was too
short to fit correctly into the lever arm.

Mike

> -----Original Message-----
> From: xxx@xxx.xxx.edu [mailto:xxx@xxx.xxx.edu] On
> Behalf Of Cor van de Water
> Sent: Wednesday, June 27, 2012 1:01 PM
> To: Electric Vehicle Discussion List
> Subject: Re: [EVDL] jumpy Pots
>
> OK, found the old thread with the pot suggestion from Lee, besides the

> obvious to go to pick-n-pull and get a TPS (Throttle Position Sensor)
> from
one
> of the cars that has drive by wire (which is essentially all modern
cars).
> My car also accepts a 0 to 3.5V input instead of the accelerator
> potmeter,
so I
> can make things work even if they are not 0-5kOhm...
>
> I noticed an old request from someone to convert a 0 - 5V signal to a
> 0 - 5kOhm resistance. That should be simple and only require an opamp
> and two identical MOSFETs. Send a fixed 1mA current through one and
> compare with the input voltage. The other represents the 0 - 5kOhm
> output based on the 0-5V input.
> In case it needs to be 5k - 0 or other conversions (for example from a

> too sensitive linear pot to logarithmic, which will allow smooth
> take-off)
then
> that is possible also.
>
> Cor van de Water
> Chief Scientist
> Proxim Wireless Corporation http://www.proxim.com
> Email: xxx@xxx.xxx Private: http://www.cvandewater.com
> Skype: cor_van_de_water XoIP: +31877841130
> Tel: +1 408 383 7626 Tel: +91 (040)23117400 x203
>
> -----Original Message-----
> From: xxx@xxx.xxx.edu [mailto:xxx@xxx.xxx.edu] On
> Behalf Of Lee Hart
> Sent: Tuesday, September 29, 2009 9:04 AM
> To: Electric Vehicle Discussion List
> Subject: Re: [EVDL] jumpy Pots
>
> Electric Blue auto convertions wrote:
> > I have only had 3 pots go bad so far and they were with in the first

> > year. NOW if you see what Fork lifts use, the same thing only built
> > much better and are still 5K ohm they last forever, BUT if you call
> > Hyster, Cat, or Clark they want between 50 and 70 $ for the pot
> > itself, is it worth it> thats up to you ..Wayne ev-blue.com
>
> Try MIL style RV4. There are many manufacturers (like the Allen
> Bradley
type
> AB I mentioned, though Allen Bradley seems to have sold their pot
> business to someone, so it's under a new name). Here's an example from
> Digikey:
>
> http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail&name=RV4N2
> 5
> 3
> C-ND
> http://www.precisionelectronics.com/MIL%20Style%20RV4%20PDF%20Dow
> nload_f
> iles/MIL%20Style%20RV4.pdf
>
> Sealed, gold plated terminals, stainless steel shaft, 25,000 cycle
rotational life,
> about $8.
> --
> Lee A. Hart | Ring the bells that still can ring
> 814 8th Ave N | Forget the perfect offering
> Sartell MN 56377 | There is a crack in everything
> leeahart earthlink.net | That's how the light gets in --
Leonard
Cohen
>
> _______________________________________________
> General EVDL support: http://evdl.org/help/ Usage guidelines:
> http://evdl.org/help/index.html#conv
> Archives: http://evdl.org/archive/
> Subscription options: http://lists.sjsu.edu/mailman/listinfo/ev
>
>
> _______________________________________________
> | Moratorium on drag racing discussion is in effect.
> | Please take those discussions elsewhere. Thanks.
> |
> | REPLYING: address your message to xxx@xxx.xxx.edu only.
> | Multiple-address or CCed messages may be rejected.
> | UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub
> | OTHER HELP: http://evdl.org/help/
> | CONFIGURE: http://lists.sjsu.edu/mailman/listinfo/ev

_______________________________________________
| Moratorium on drag racing discussion is in effect.
| Please take those discussions elsewhere. Thanks.
|
| REPLYING: address your message to xxx@xxx.xxx.edu only.
| Multiple-address or CCed messages may be rejected.
| UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub
| OTHER HELP: http://evdl.org/help/
| CONFIGURE: http://lists.sjsu.edu/mailman/listinfo/ev

_______________________________________________
| Moratorium on drag racing discussion is in effect.
| Please take those discussions elsewhere. Thanks.
|
| REPLYING: address your message to xxx@xxx.xxx.edu only.
| Multiple-address or CCed messages may be rejected.
| UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub
| OTHER HELP: http://evdl.org/help/
| CONFIGURE: http://lists.sjsu.edu/mailman/listinfo/ev
 
#68 ·
Re: [EVDL] jumpy Pots

Cor,
Perhaps you should draw something up and post it (you could use the free
schematic/layout
program www.expresspcb.com for example). Sometimes my attention span is not
very good when reading a description without a schematic where I can visualize
it immediately.
I does sound like this will work since the program just looks for an accelerator
input of less than 2.5V
when the start switch is open (indicating there is a problem since the start
switch is open and it appears
as if the accel is pressed,)
LDA ACC_AD ;ACC<2.5V
CMP #80H
BHI S_CKA
STPEN: BRCLR 0,PORTA,FR_T ;1=ST OPEN
LDA #05H ;FLT 5

Here's the situation I believe your seeing, FLT 7 when voltage is too high
(above 3.7V)
CA_T: LDA ACC_AD
CMP #0BDH ;3.7V,189
BLS IATT
BSET 3,AFLAG
BRSET 7,EFLAG,IAT ;1=TMM FLT
LDA #07H ;FLT 7,ACC>3.7
BSET 1,BFLAG ;FLT FLAG
JSR DISP




----- Original Message ----
From: Cor van de Water <xxx@xxx.xxx>
To: Electric Vehicle Discussion List <xxx@xxx.xxx.edu>
Sent: Thu, June 28, 2012 2:31:50 AM
Subject: Re: [EVDL] jumpy Pots

My setup is not a standard potbox anyway.
It has the pot mounted in a bracket and on its shaft
is a metal piece with a set screw and a U-shaped hole.
In that hole sits a pin which can slide left and right
on another shaft. Next to that is also a metal block
which pushes the microswitch as soon as entire thing
starts sliding.
That contraption is not directly operated by the cable
from the pedal, but instead a lever is mounted where the
cable pulls on one end and the other end operates this
contraption, which also has return spring built-in.
It is a very universal and clever mechanical design,
but if you look at modern TPS assemblies attached to
the pedal itself, then you wonder why we make some
things so complex.
Same here - the whole deal with the microswitch selecting
between idle run and the pot, causing the controller to
throw errors when the input voltage goes over 3.7 during
the switch...
I was thinking about the whole deal and decided that the
simples solution is to send more current through the pot.
The upper 1.2 or 1.5kOhm is working well (little use) so
if I just increase the current by 2mA then the 3.6V to 0
range is the upper half of the pot.
To avoid that the input voltage goes too high and to
get a stable idle RPM, I will simply add a so-called
programmable zener like a TL431 and re-purpose the already
present trimpot and series resistor as the 2.5V divider
for the zener. This means that I can solder the TL431 on
that combination, add a pull-up resistor to send 2mA more
into the pot, remove the microswitch wires and simply
wire the zener in parallel to the pot and I am done.
I like it whem solutions are simple.

Cor van de Water
Chief Scientist
Proxim Wireless Corporation http://www.proxim.com
Email: xxx@xxx.xxx Private: http://www.cvandewater.com
Skype: cor_van_de_water XoIP: +31877841130
Tel: +1 408 383 7626 Tel: +91 (040)23117400 x203

-----Original Message-----
From: xxx@xxx.xxx.edu [mailto:xxx@xxx.xxx.edu] On
Behalf Of Mike Nickerson
Sent: Wednesday, June 27, 2012 10:39 PM
To: 'Electric Vehicle Discussion List'
Subject: Re: [EVDL] jumpy Pots

When ordering the pot, be very careful to determine the length of the
shaft and make sure it's compatible with the pot already in the potbox.
My first try, I got a pot that looked compatible, but the shaft was too
short to fit correctly into the lever arm.

Mike

> -----Original Message-----
> From: xxx@xxx.xxx.edu [mailto:xxx@xxx.xxx.edu] On
> Behalf Of Cor van de Water
> Sent: Wednesday, June 27, 2012 1:01 PM
> To: Electric Vehicle Discussion List
> Subject: Re: [EVDL] jumpy Pots
>
> OK, found the old thread with the pot suggestion from Lee, besides the

> obvious to go to pick-n-pull and get a TPS (Throttle Position Sensor)
> from
one
> of the cars that has drive by wire (which is essentially all modern
cars).
> My car also accepts a 0 to 3.5V input instead of the accelerator
> potmeter,
so I
> can make things work even if they are not 0-5kOhm...
>
> I noticed an old request from someone to convert a 0 - 5V signal to a
> 0 - 5kOhm resistance. That should be simple and only require an opamp
> and two identical MOSFETs. Send a fixed 1mA current through one and
> compare with the input voltage. The other represents the 0 - 5kOhm
> output based on the 0-5V input.
> In case it needs to be 5k - 0 or other conversions (for example from a

> too sensitive linear pot to logarithmic, which will allow smooth
> take-off)
then
> that is possible also.
>
> Cor van de Water
> Chief Scientist
> Proxim Wireless Corporation http://www.proxim.com
> Email: xxx@xxx.xxx Private: http://www.cvandewater.com
> Skype: cor_van_de_water XoIP: +31877841130
> Tel: +1 408 383 7626 Tel: +91 (040)23117400 x203
>
> -----Original Message-----
> From: xxx@xxx.xxx.edu [mailto:xxx@xxx.xxx.edu] On
> Behalf Of Lee Hart
> Sent: Tuesday, September 29, 2009 9:04 AM
> To: Electric Vehicle Discussion List
> Subject: Re: [EVDL] jumpy Pots
>
> Electric Blue auto convertions wrote:
> > I have only had 3 pots go bad so far and they were with in the first

> > year. NOW if you see what Fork lifts use, the same thing only built
> > much better and are still 5K ohm they last forever, BUT if you call
> > Hyster, Cat, or Clark they want between 50 and 70 $ for the pot
> > itself, is it worth it> thats up to you ..Wayne ev-blue.com
>
> Try MIL style RV4. There are many manufacturers (like the Allen
> Bradley
type
> AB I mentioned, though Allen Bradley seems to have sold their pot
> business to someone, so it's under a new name). Here's an example from
> Digikey:
>
> http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail&name=RV4N2
> 5
> 3
> C-ND
> http://www.precisionelectronics.com/MIL%20Style%20RV4%20PDF%20Dow
> nload_f
> iles/MIL%20Style%20RV4.pdf
>
> Sealed, gold plated terminals, stainless steel shaft, 25,000 cycle
rotational life,
> about $8.
> --
> Lee A. Hart | Ring the bells that still can ring
> 814 8th Ave N | Forget the perfect offering
> Sartell MN 56377 | There is a crack in everything
> leeahart earthlink.net | That's how the light gets in --
Leonard
Cohen
>
> _______________________________________________
> General EVDL support: http://evdl.org/help/ Usage guidelines:
> http://evdl.org/help/index.html#conv
> Archives: http://evdl.org/archive/
> Subscription options: http://lists.sjsu.edu/mailman/listinfo/ev
>
>
> _______________________________________________
> | Moratorium on drag racing discussion is in effect.
> | Please take those discussions elsewhere. Thanks.
> |
> | REPLYING: address your message to xxx@xxx.xxx.edu only.
> | Multiple-address or CCed messages may be rejected.
> | UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub
> | OTHER HELP: http://evdl.org/help/
> | CONFIGURE: http://lists.sjsu.edu/mailman/listinfo/ev

_______________________________________________
| Moratorium on drag racing discussion is in effect.
| Please take those discussions elsewhere. Thanks.
|
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#69 ·
Re: [EVDL] jumpy Pots

I don't see why it is so hard to have a pot go from 0 to 100 ohms on the first
half of the throw and 100 to 5000 ohms on the second half. It's the way a gas
engine works. Electric has no lag therefore it's jerky. I have a standard
Curtis pot and it is tricky to start. My daughter won't even drive it. I'd
love to find a specialized pot. Maybe a series of pots in parallel or series.
I start my ev in first gear and leave it there until I get to 25mph. Once
started and rolling no problem. It's overcoming the start with just the right
push that is tricky. Worst case my car bucks like a bucking bronco. Lawrence
Rhodes....but it is possible but takes about 5 seconds to do smoothly.

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#70 ·
Re: [EVDL] jumpy Pots

Some controllers have that feature built in. For example, you can set what percentage PWM half-throttle is. If you set it to, say, 30%, then the first half of the throttle is 0% - 30%, and the second half of the throttle is 30% - 100%.

Bill

----- Original Message -----
From: Lawrence Rhodes <xxx@xxx.xxx>
To: xxx@xxx.xxx.edu
Sent: Thu, 28 Jun 2012 14:16:46 -0400 (EDT)
Subject: Re: [EVDL] jumpy Pots

I don't see why it is so hard to have a pot go from 0 to 100 ohms on the first
half of the throw and 100 to 5000 ohms on the second half. It's the way a gas
engine works. Electric has no lag therefore it's jerky. I have a standard
Curtis pot and it is tricky to start. My daughter won't even drive it. I'd
love to find a specialized pot. Maybe a series of pots in parallel or series.
I start my ev in first gear and leave it there until I get to 25mph. Once
started and rolling no problem. It's overcoming the start with just the right
push that is tricky. Worst case my car bucks like a bucking bronco. Lawrence
Rhodes....but it is possible but takes about 5 seconds to do smoothly.

_______________________________________________
| Moratorium on drag racing discussion is in effect.
| Please take those discussions elsewhere. Thanks.
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| REPLYING: address your message to xxx@xxx.xxx.edu only.
| Multiple-address or CCed messages may be rejected.
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#71 ·
Re: [EVDL] jumpy Pots

> I don't see why it is so hard to have a pot go from 0 to 100 ohms on the =
first
> half of the throw and 100 to 5000 ohms on the second half. It's the wa=
y a gas

> engine works.

I used to write firmware for electric fork lift controllers and we did this=
in firmware, i.e. interpret 0 to 2500 ohms as if it were 0 to 2% throttle =
and 2500 to 5k ohms as if 2% to 100% throttle. It was all to make the tr=
uck feel more like gas powered. Unless the microcontroller used was comp=
letely out of memory the feature was free and only involved a little time t=
o develop. I would sort of expect Curtis to have asimilarfeature, =
maybe on fancier controllers?

-Chris Darilek



________________________________
From: Lawrence Rhodes <xxx@xxx.xxx>
To: xxx@xxx.xxx.edu =

Sent: Thursday, June 28, 2012 1:16 PM
Subject: Re: [EVDL] jumpy Pots
=

I don't see why it is so hard to have a pot go from 0 to 100 ohms on the fi=
rst =

half of the throw and 100 to 5000 ohms on the second half. It's the way =
a gas =

engine works. Electric has no lag therefore it's jerky. I have a stan=
dard =

Curtis pot and it is tricky to start. My daughter won't even drive it.=
I'd =

love to find a specialized pot. Maybe a series of pots in parallel or se=
ries. =

I start my ev in first gear and leave it there until I get to 25mph. Onc=
e =

started and rolling no problem. It's overcoming the start with just the rig=
ht =

push that is tricky. Worst case my car bucks like a bucking bronco. L=
awrence =

Rhodes....but it is possible but takes about 5 seconds to do smoothly.

_______________________________________________
| Moratorium on drag racing discussion is in effect.
| Please take those discussions elsewhere. Thanks.
|
| REPLYING: address your message to xxx@xxx.xxx.edu only.
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#72 ·
Re: [EVDL] jumpy Pots

Lawrence,
Is your pot the same setup as Lee explained for standard
Curtis - 5k is idle (no power) and 0 is max power?
there are not many pots that are reverse logarithmic,
where the are of small changes is at the high end of
the scale, while the large changes appear at the low
end of the scale.
It can be made of course, but that is not standard.
Also it is difficult to get right, if the small steps
all go from 5k to 4.7k and then it starts increasing
faster, while your controller only starts delivering
power when it sees the throttle go below 4.5k then
you are still missing all that fine control and
immediately jumping to the large steps.
So, sometimes it is better to have a linear pot
and convert the output to what you want to get,
either with series/parallel resistors or an
electronic conversion or - preferably - in software.

Regards,

Cor van de Water
Chief Scientist
Proxim Wireless Corporation http://www.proxim.com
Email: xxx@xxx.xxx Private: http://www.cvandewater.com
Skype: cor_van_de_water XoIP: +31877841130
Tel: +1 408 383 7626 Tel: +91 (040)23117400 x203

-----Original Message-----
From: xxx@xxx.xxx.edu [mailto:xxx@xxx.xxx.edu] On
Behalf Of Lawrence Rhodes
Sent: Thursday, June 28, 2012 11:17 AM
To: xxx@xxx.xxx.edu
Subject: Re: [EVDL] jumpy Pots

I don't see why it is so hard to have a pot go from 0 to 100 ohms on the
first half of the throw and 100 to 5000 ohms on the second half. It's
the way a gas engine works. Electric has no lag therefore it's jerky.
I have a standard Curtis pot and it is tricky to start. My daughter
won't even drive it. I'd love to find a specialized pot. Maybe a
series of pots in parallel or series.
I start my ev in first gear and leave it there until I get to 25mph.
Once started and rolling no problem. It's overcoming the start with just
the right push that is tricky. Worst case my car bucks like a bucking
bronco. Lawrence Rhodes....but it is possible but takes about 5 seconds
to do smoothly.

_______________________________________________
| Moratorium on drag racing discussion is in effect.
| Please take those discussions elsewhere. Thanks.
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#73 ·
Re: [EVDL] jumpy Pots

On 28 Jun 2012 at 11:16, Lawrence Rhodes wrote:

> I don't see why it is so hard to have a pot go from 0 to 100 ohms on the first
> half of the throw and 100 to 5000 ohms on the second half. It's the way a gas
> engine works.

Two thoughts on this.

First, I understand why many builders (especially the major automakers) want
EVs to act like ICEVs - because that's what most drivers are used to.
Still, I find it annoying that they insist on building in a simulation of
automatic trans creep, which I consider one of the major downsides of a
slushbox. I also get my back up at the idea of adding noisemakers to an
inherently quiet EV, but that's a losing battle. Do I want them to simulate
ALL the action of an ICEV throttle in an EV? No thanks.

Second, not all ICEVs act that way. Indeed, I wish they would. My
workplace has a Mazda Tribute (Ford Explorer clone) and I find it impossible
to drive smoothly. All the throttle action happens in the first inch or so
of pedal travel. To make things worse, the pedal is stiffly spring so that
it acts almost like a toggle switch. When I try to pull away from a stop,
at first I get nothing, and then with a harder press, suddenly the machine
lunges ahead. My coworkers don't understand what I'm talking about when I
describe it, which leads me to suspect that this behavior isn't too uncommon
in ICEVs. It reminds me of the analog volume controls on cheap consumer
stereo outfits back in the 1980s, set so that the set was close to full
volume at about 12:00 position to make ignorant customers think it was more
powerful than the ones with smoother volume control.

David Roden - Akron, Ohio, USA
EVDL Administrator

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EVDL Information: http://www.evdl.org/help/
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Note: mail sent to "evpost" and "etpost" addresses will not
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#74 ·
Re: [EVDL] jumpy Pots

I have a modified Curtis 1221B modified for 144vdc and needs 0 to 5K. So I'd
like very little change in the first half and most in the second half. Lawrence
Rhodes......

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