HELP me build a gas gauge????

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

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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
 
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

 
Very cool looking design.

As said already there are a zillion different LED designs. You might want to consider looking around before freezing your project.

Here are just a few ideas:

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Lefty
 
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

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i kinda liked this one a little
 
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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.
 
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
 
looks like a nice display

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

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


one place to ordere
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but they are avalible at lots of places
 
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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.
 
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
 
browningbuck said:
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
Click to expand...

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
 
browningbuck said:
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
Click to expand...


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


hey guys i have a 12V system and need help to figure out a solution to this problem...okay i dont need help...i need some one to hold my hand through this

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Click to expand...

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


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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
 
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 hm: , the maximum level to 132 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.
 

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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.
 
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