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HELP me build a gas gauge????

Discussion in 'Electronic Projects Design/Ideas/Reviews' started by browningbuck, Dec 4, 2007.

  1. browningbuck

    browningbuck New Member

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    here is why i cant use 10...i could use sx like i said earlier..not enough room

    [​IMG]
    this is a small little buisness i have putting intergrated gear indicators on bikes (the 7 seg. display in the middle) then bunches of people wanted me to design a fuel gauges and thats where i am at (the fuel leds are just photoshoped as you can tell :) ) BOY I LOVE LEDs
     
  2. chemelec

    chemelec Well-Known Member

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    Well there are Small LED's and there are SMALLER LED's.

    I have some here that are only 1/16 Inch Square.
    Side by Side, 10 would be 5/8 Inch Long.

    But Anyway, Have FUN.

    GARY

     
  3. Leftyretro

    Leftyretro New Member

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  4. dave

    Dave New Member

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  5. browningbuck

    browningbuck New Member

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    only reason i can down grade in size is due to mcd they will in the end have a photo resistor, and have to be bright enough in the day to be clairly visable, on a motorcycle, and plus 5 is cheaper and more simple for me to sell :) (less holes i have to drill in an $80 face plate)

    i still have a prob with getting this in bar mode instead of dot :( i have tried as said before connecting pin 3 and 9 (no luck) any sugestions????? and the project has not been put on pause it was just the weekend :) i had to work on 3 sets of gauges

    [​IMG]

    i kinda liked this one a little
     
    Last edited: Dec 10, 2007
  6. TrevorP

    TrevorP New Member

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    To get it in bar mode simply provide power to the Mode Node...if that doesn't work then something is messed and you should try another chip of the same type.
     
  7. browningbuck

    browningbuck New Member

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    okay i did hook up mode to power, but nothing...i had to get an NTE1508 instead of the LM3914 but it says its a dot / bar????? and did try a new chip..nothing different:(
     
  8. Darth Bagel

    Darth Bagel New Member

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    http://www.electro-tech-online.com/custompdfs/2007/12/nte1508.pdf

    Have you checked the voltage on the mode node yet, as in with an instrument of some sort?
     
  9. browningbuck

    browningbuck New Member

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    they measure within .001 volt of each other ???? it seems like this should work
     
  10. browningbuck

    browningbuck New Member

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    http://www.electro-tech-online.com/attachments/fuel-gif.15847/


    okay so i am working out some bugs still on this and was wondering where to stick a photo resistor on this cicuit to make it dim when there isnt much light???? i also ordered a new chip to see if that was the problem on getting the thing to light up as Bar instead of dot, being connecting pin nine to V+ didnt work
     
  11. matk95

    matk95 Member

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    looks like a nice display

    if you dont want to have to drill loads of holes then you could use a led bargraph

    [​IMG]

    they are avilible in many colours and are small enoughf to fit esily onto the space you have


    one place to ordere
    http://www.elexp.com/opt_0ida.htm

    but they are avalible at lots of places
     
    Last edited: Dec 17, 2007
  12. chemelec

    chemelec Well-Known Member

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    I Doubt this can Work in Bar Mode, Because my design is running the display in Reverse.

    To get Bar Mode, you would require Reversing the input voltage with an Op-amp and operating in Normal mode.
     
  13. browningbuck

    browningbuck New Member

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    oh crap so i can either ask everyone how to wire up an Op-amp, or as how to wire this up to work in normal mode with out an op-amp....


    anyone feel like helping me out?????

    Chemelec you have been kicking butt, and thanks for everything :)
     
  14. chemelec

    chemelec Well-Known Member

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    If you Email me with the Info, I'll see about doing up a Proto-type circuit up for you, with the Inverter circuit and the bar display.

    I Need All the Info Again, including those resistances of the gas sender unit!

    And I would Definately Recommend you go with 10 Leds, 5 won't give enough accuracy.

    Gary
     
  15. SPDCHK

    SPDCHK Member

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    BTW. You do not have your location filled in. Where in the world are you?
     
  16. browningbuck

    browningbuck New Member

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    okay here is the information....

    the systemwith 5 leds has been working FLAWLESSLY...i should get you a vid up tonight when i get to my camera. it is sooooo accurate that i couldnt ask for anything more. but i am still willing to start with a fresh idea so tell me what else you would need. if anything i think 6 would be BEST... so that i could have 5 lights noting in a bar like this picture and the 6th kicking on the gas light like so


    [​IMG]
    [​IMG]
     
    Last edited: Dec 18, 2007
  17. Darth Bagel

    Darth Bagel New Member

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    Could you draw a schematic of what you've got right now? I'm a little bit confused.
     
  18. browningbuck

    browningbuck New Member

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    http://www.electro-tech-online.com/a...f?d=1196962611

    this is what i have so far.... i dont think it will EVER work in Bar mode due to the theory behind it, so i think i might need to start from scratch...and i want to do it with a photoresistor and 6 leds. let me know if you can help....GOD you guys are BAD A$$ SOBs wiht this stuff and i thank you for everything.

    Brian
     
  19. on1aag

    on1aag New Member

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    Hi Browningbuck,

    Maybe you need a different approach, I think the circuit is too
    complicated. If you send a constant current through the gas
    gauge the voltage across it's terminals will be proportional to
    it's resistance. Then you can measure this voltage with the
    LM3914, nothing to it but, there always is a but . . .
    The LM3914 should drive five leds, the minimum level should
    correspond to 12 :eek:hm: , the maximum level to 132 :eek:hm: .
    No problem (?) if you could build your own LM3914 to meet
    your specifications, in practice there is a minimum level and
    the maximum level is ten times the minimum level.
    So I decided to apply a constant current of 10 mA to the gas
    gauge, set the lowest indicator level for the LM3914 to 128 mV
    and the highest indicator level to 1280 mV.
    Which also means that there are ten indicator levels on five leds.
    Off, half brightness, full brightness.
    I also decreased the led drive current of the LM3914 to approx.
    5 mA per output. There is only one difficulty left and that's the
    construction, everything that is connected to ground should be
    connected directly to one single point.

    on1aag.
     

    Attached Files:

  20. chemelec

    chemelec Well-Known Member

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    I Already Told you it Won;t work in Bar Mode the way I did it. But I can fix that if you give me a bit of time.

    Too many things to do all at once.
     
  21. Super_voip

    Super_voip New Member

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    A simple solution for the bar display may be to mount the LEDS in reverse order.
     

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