omega 24 v6
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| posted on 10/11/07 at 06:18 PM |
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LED fuel gauge
I found this on the interweb Led fuel gauge
Will it work??
Can someone explain the way that it works in simple terms ?
I like the idea of building one where as the fuel level decreases the no of leds lit decreases until it finally lights a previously unlit fuel pump
logo.
Could this be done?? I am electrically literate but not electronically specialized.
Edited to say i've just realised (i think) that the 10 resistors are actually pots. Is that right??
[Edited on 10/11/07 by omega 24 v6]
If it looks wrong it probably is wrong.
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Confused but excited.
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| posted on 10/11/07 at 06:53 PM |
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Yes they are pots.
I presume they were fitted so that the indicator lights can be individually calibrated to allow for the shape of the tank, to give a linear
relationship to fuel level. HTH.
Operation:
The 220 ohm resistor and the fuel level sender form a potential divider.
As the fuel level changes the voltage at this point varies.
The comparator senses the voltage difference at the point between the 220 ohmresistor and the level sender and a preset value determined by a preset
pot..
As the voltage changes each comparator detects the voltage, relevant to the reference voltage determined by the preset pot.
The output of each comparator flips on/off and latches at the required value.
[Edited on 10/11/07 by Confused but excited.]
Tell them about the bent treacle edges!
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ghuncha
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| posted on 10/11/07 at 06:59 PM |
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very simple.....
the comparator basically compares the voltage... the variable 10k resistor on each negative are set to give a certain voltage level to the comparator,
the adjustment is such that the voltage increases as we go up....
the sender is connected in series with 220 ohm resistor, as the resistance of the sender changes the voltage on the comparator also changes..
when the voltage on the positive leg of the comparator becomes greater than the voltage on the negative leg, the comparator output becomes positive
and hence led lights...
easy but needs alot of adjustment....
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rallyingden
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| posted on 10/11/07 at 07:07 PM |
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Yes they are pots and as "Confused" said they are used to calibrate when each of the LED's are turned on.
The resistance of the sender changes due to fule being added or removed from the tank.
The resistance of each Pot & LED is compared by the Electrinic chip to the resistance of the sender. If they are the same then the LED
illuminates.
Yoy would have to calibrate this guage by adding a known quantity of fuel then adjusting the pot to indicate the current level, adding more fuel, then
adjusting the next pot ....... and so on till the whole range has been done.
Hope this helps
RD 
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triafgg
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| posted on 10/11/07 at 11:10 PM |
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Fantastic job, looks really smart.
Anyone able and willing to provide a PCB/Breadboard layout for an electronics novice?
Would be appreciated.
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