[DeTomaso] Fuel Gage Linearizer

Tomas Gunnarsson guson at home.se
Sun Nov 2 09:21:40 EST 2008 

There's more info on Thomas' web site;

http://www.detomaso.nu/~thomast/gauge-corrector/

Tomas

----- Original Message ----- 
From: "John Taphorn" <jtaphorn at kingwoodcable.com>
To: "Edward A. Nauman" <enauman at roadrunner.com>; "Email Forum Pantera" <detomaso at realbig.com>
Sent: Sunday, November 02, 2008 2:42 PM
Subject: Re: [DeTomaso] Fuel Gage Linearizer


> Ed
> 
> Several years back, Thomas Tornblom offered his electrical engineering 
> expertise to the group with an alternative solution he called his Gauge 
> Corrector.
> 
> It is an adjustable eeprom to match the sender to any gauge.  If I recall 
> correctly, the eeprom can store 10 data points.  Thus, I was able to adjust 
> my fuel gauge to read accurately at 1/8th intervals by filling the tank 2.65 
> gals at a time and storing the value.  Of course, it assumes that the 
> quantity of fuel used between those data points is linear for a given drop 
> in the float arm.  However, accuracy at 1/8th intervals is close enough for 
> me.  Obviously, if you are using a data point for every gallon verses 2.65 
> gals, your approach will be more accurate between my 1/8th data points.
> 
> Although a benefit of Tom's eeprom approach is that I was able to calibrate 
> it myself and could easily perform the operation again should I change my 
> gauges to a set with a different impedance.  I.E. I am currently using it on 
> my Auto Meter, but could have used it on my Veglia initially.
> 
> I don't know if Thomas is still offering the product.  It was very 
> inexpensive and has the JT Seal of Approval.
> 
> I am not trying to discourage your idea or willingness to help, simply 
> illuminating the possibilities and the contributions of others.
> 
> JT
> 
> 
> ----- Original Message ----- 
> From: "Edward A. Nauman" <enauman at roadrunner.com>
> To: "Email Forum Pantera" <detomaso at realbig.com>
> Sent: Saturday, November 01, 2008 1:56 PM
> Subject: [DeTomaso] Fuel Gage Linearizer
> 
> 
>> Hi guys,
>>
>>        I have been away from the list for a while and was searching 
>> through
>> the archives.  I came across a message about a circuit I designed a couple
>> of years ago.  Being an instrumentation engineer for 3 decades, one of my
>> pet peeves developed over the years is the non-linearity of automotive 
>> fuel
>> gages.  The fuel gage in most cars is really a fuel level gage and not a
>> fuel quantity gage.  Since the fuel level transducer is usually a 
>> wire-wound
>> potentiometer actuated by a float at the end of an arm, the potentiometer
>> output is proportional to the angle of the float arm which is a sinusoidal
>> function.  Most of the automotive fuel level pots I have examined have a
>> linear output with respect to rotation angle of the shaft.  So, the fuel
>> level with respect to the output of the potentiometer becomes a function 
>> of
>> the length of the float arm and the sin of it's angle.  In other words the
>> measurement, if uncorrected, is non-linear.  This is sometimes corrected 
>> for
>> by manufacturing a non-linear pot that linearizes the sinusoidal output in
>> the range of interest.  Remember, that is for fuel LEVEL.  When you
>> translate level into quantity. The shape of the fuel tank becomes the next
>> source of non-linearity.  Obviously if you had a cone shaped tank, one 
>> inch
>> of fuel level near the top is a lot more than quantity 1 inch at the 
>> bottom.
>> Depending on the irregularity of the cross-sectional area of the tank as 
>> the
>> fuel level rises, the equation for quantity Vs. level can get quite
>> complicated.  The simplest way to correct the situation and still be
>> adaptable to different tank shapes and sizes is to use a micro-controller
>> and a calibrated look up table to translate the level into actual 
>> quantity.
>> The design I came up with for my car uses a PIC microcontroller that has 
>> on
>> board an EEPROM to store the look-up table.  Operationally, the fuel level
>> potentiometer is connected to my circuit which reads the resistance and
>> "looks up" the correct corresponding fuel quantity. It then drives the 
>> gage
>> with the correct voltage to indicate the actual quantity.  The setup
>> requires calibrating the tank at 1 gallon intervals which means draining 
>> the
>> tank and filling it one gallon at a time.  Since I was only building one 
>> of
>> these circuits for myself, I did not write any code to have the micro
>> perform the calibration automatically, meaning, that I recorded ADC output
>> on my computer, generated the lookup table with Excel and manually entered
>> the lookup table into the micro.  I did the same thing for the one I built
>> for Chuck Buthala.  But that meant he had to perform the calibration, 
>> email
>> me the data, and I programmed his look up table and sent the box to him.
>>
>>        If you guys are interested in something like this, I can do 1 of 2
>> things.  I can put together a kit consisting of a PCB and a parts list 
>> with
>> a schematic and a wiring diagram.  Or, I can build you one and send it to
>> you with installation instructions.  But unless you are familiar with PIC
>> microcontrollers and own a programmer, you would have to send me the data
>> and I would have to program it and send it back to you.  In order for me 
>> to
>> write the code for an auto calibration routine, I would have to have 
>> enough
>> commitments to justify the time spent.  Bear in mind, I'm not trying to 
>> make
>> money here, just offering this to my Pantera brothers if they are
>> interested.  If there is enough interest, I will figure out a price based 
>> on
>> the responses I get.
>>
>>
>>        Cheers,
>>
>>               Fast Eddie  (#2100)
>>
>>
>> P.S.  If my explanation is either too complicated or too simple, please 
>> let
>> me know and I will clarify any questions you may have.
>>
>>
>>
>>
>>
>> Edward A. Nauman\
>>
>> C.E.O.
>>
>> Smart Litez Inc
>>
>>
>>
>> Palmdale, CA. 93551
>>
>> (661) 305-7636
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>>The circuit was designed by Ed Nauman.  He built one for me and it works
>> great.  The gizmo works with a chip which uses the sending unit 
>> resistance,
>> compares it to a look up table in the memory and >sends the correct signal
>> to the gage.  You have to go though a calibration cycle to set it up. 
>> There
>> is an article in the POCA news about two years ago on the circuit.  Ed if
>> your listening I hope my >description is correct.
>>
>>>"www.ProvaMo.com" <pantera007 at sbcglobal.net
>> <http://list.realbig.com/mailman/listinfo/detomaso> > wrote:   It was not
>> "Me" Chuck that Ohm'ed, but I did test one gallon at a time, the
>>>ohming was, I think, someone in the Nordic region perhaps.
>>
>>>Chuck
>>
>>
>> -----Original Message-----
>> From: detomaso-bounces at realbig.com
>> <http://list.realbig.com/mailman/listinfo/detomaso>
>> [mailto:detomaso-bounces at realbig.com
>> <http://list.realbig.com/mailman/listinfo/detomaso> ]On
>> Behalf Of Mark McWhinney
>> Sent: Tuesday, July 24, 2007 10:41 AM
>> To: 'Garth Rodericks'; detomaso at realbig.com
>> <http://list.realbig.com/mailman/listinfo/detomaso>
>> Subject: Re: [DeTomaso] Incorrect gas gauge
>>
>>
>> Some of the fancier aftermarket gauges allow for multiple calibration
>> points. I think little Larry has that. If he is lurking, may he can fill
>> us in.
>>
>> As I recall, Chuck did the one-gallon at a time work to record the ohm
>> readings.
>>
>>
>> -----Original Message-----
>> From: detomaso-bounces at realbig.com
>> <http://list.realbig.com/mailman/listinfo/detomaso>
>> [mailto:detomaso-bounces at realbig.com
>> <http://list.realbig.com/mailman/listinfo/detomaso> ] On
>> Behalf Of Garth Rodericks
>> Sent: Tuesday, July 24, 2007 10:33 AM
>> To: detomaso at realbig.com
>> <http://list.realbig.com/mailman/listinfo/detomaso>
>> Subject: [DeTomaso] Incorrect gas gauge
>>
>> Just another reference point for the non-calibrated nature of our gas
>> gauges.
>>
>> When mine is full it registers Full.
>> 40 miles after fill up it registers at the 3/4 mark, or slightly below.
>> But I can drive for quite a long time between 1/2 tank and Empty.
>> And, at Empty the warning light comes on.
>>
>> I have not tested how far I can go after the warning light comes on,
>> however the most I've
>> been able to add at a fill up was 19.5 gallons.
>>
>> Now, I recall a year or two back that someone posted that they made a
>> simple electronic
>> converter to calibrate the fuel gauge. I think they took ohm readings from
>> the sender as they
>> filled the tank 1 gallon at a time, then created a mapping table to send
>> an accurate reading
>> to the gauge. Does anyone remember who that was? I recall they were
>> planning to make it
>> available for sale, but I never saw anything more on it. Does anyone have
>> more info? I'd like
>> one.
>>
>> Cheers!
>> Garth
>> #4033
>>
>> YMMV,
>> Garth
>> #4033
>>
>>
>> ---------------------------------
>> Need a vacation? Get great deals to amazing places on Yahoo! Travel.
>> _______________________________________________
>>
>> Detomaso Forum Managed by POCA
>>
>> Archive Search Engine Now Available at http://www.realbig.com/detomaso/
>>
>> DeTomaso mailing list
>> DeTomaso at list.realbig.com
>> <http://list.realbig.com/mailman/listinfo/detomaso>
>> http://list.realbig.com/mailman/listinfo/detomaso
>>
>>
>> _______________________________________________
>>
>> Detomaso Forum Managed by POCA
>>
>> Archive Search Engine Now Available at http://www.realbig.com/detomaso/
>>
>> DeTomaso mailing list
>> DeTomaso at list.realbig.com
>> <http://list.realbig.com/mailman/listinfo/detomaso>
>> http://list.realbig.com/mailman/listinfo/detomaso
>> No virus found in this incoming message.
>> Checked by AVG Free Edition.
>> Version: 7.5.476 / Virus Database: 269.10.17/915 - Release Date: 7/24/2007
>> 1:50 PM
>>
>> No virus found in this outgoing message.
>> Checked by AVG Free Edition.
>> Version: 7.5.476 / Virus Database: 269.10.17/915 - Release Date: 7/24/2007
>> 1:50 PM
>>
>> _______________________________________________
>>
>> Detomaso Forum Managed by POCA
>>
>> Archive Search Engine Now Available at http://www.realbig.com/detomaso/
>>
>> DeTomaso mailing list
>> DeTomaso at list.realbig.com
>> <http://list.realbig.com/mailman/listinfo/detomaso>
>> http://list.realbig.com/mailman/listinfo/detomaso
>>
>>
>>
>> ---------------------------------
>> Pinpoint customers who are looking for what you sell.
>>  _____
>>
>>
>> * Previous message: [DeTomaso]
>> <http://www.realbig.com/pipermail/detomaso/2007-July/086859.html> 
>> Incorrect
>> gas gauge
>> * Next message: [DeTomaso]
>> <http://www.realbig.com/pipermail/detomaso/2007-July/086861.html> 
>> Incorrect
>> gas gauge
>> * Messages sorted by: [
>> <http://www.realbig.com/pipermail/detomaso/2007-July/date.html#86863> 
>> date
>> ] [ 
>> <http://www.realbig.com/pipermail/detomaso/2007-July/thread.html#86863>
>> thread ] [
>> <http://www.realbig.com/pipermail/detomaso/2007-July/subject.html#86863>
>> subject ] [
>> <http://www.realbig.com/pipermail/detomaso/2007-July/author.html#86863>
>> author ]
>>
>>
>>
>>
>>
>>
>>
>> _______________________________________________
>>
>> Detomaso Forum Managed by POCA
>>
>> Archive Search Engine Now Available at http://www.realbig.com/detomaso/
>>
>> DeTomaso mailing list
>> DeTomaso at list.realbig.com
>> http://list.realbig.com/mailman/listinfo/detomaso 
> 
> _______________________________________________
> 
> Detomaso Forum Managed by POCA
> 
> Archive Search Engine Now Available at http://www.realbig.com/detomaso/
> 
> DeTomaso mailing list
> DeTomaso at list.realbig.com
> http://list.realbig.com/mailman/listinfo/detomaso

More information about the DeTomaso mailing list