[DeTomaso] Fuel Gage Linearizer

Asa Jay Laughton asajay at asajay.com
Sun Nov 2 11:40:26 EST 2008


Looks like a pretty simple design.  There are any number of PCB board 
houses in the U.S. that will do limited runs for darn near next to 
nothing.  In some cases the only limitation is that you have to use 
their layout software (usually a free download).  They can even do 
double sided for pretty much the same price.  By the look of the 
components, Digi-key would be an easy way to obtain the parts, and they 
come even cheaper in quantities.

And as pointed out on the website, they aren't Pantera specific, so 
there is a whole other market out there for them as well.

These would be super simple to sell as a kit, and probably only take 
about 30 minutes of labor to sell as a complete package, including 
printed instructions.  Just the kind of thing I wouldn't mind taking 
on.... if I had the time.  ;)

Asa Jay

Asa Jay Laughton, MSgt, USAFR, Retired

& Shelley Marie
Spokane, WA

1971 Mach I Mustang  [ASA JAY]
1973 Pantera L 5533  [ASASCAT]
    
******************************     
http://www.asajay.com
http://www.351c.info
  



Thomas Tornblom wrote:
> If anyone is willing to make and distribute the correctors, I'd be  
> happy to donate the work I've put in to it.
>
> I like to design stuff, but I get bored quickly ;-)
>
> Thomas
>
>
>
> 2 nov 2008 kl. 06.21 skrev "Tomas Gunnarsson" <guson at home.se>:
>
>   
>> 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
>>>       
>> _______________________________________________
>>
>> 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
>>
>> !DSPAM:490db78f22608312568212!
>>
>>     
> _______________________________________________
>
> 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