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
>
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