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Fuel level sensor/ transducer

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mrmmani22

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We need to get this for our project.. it's only a part of the project. This O/P goes to the microcontroller and so on..
So the question is..
1. Is such a thing avble commercially? OR
2. Can we design using circuits??
3. OR .. Can it be done this way??
**broken link removed**
From the figure, the magnetic float is a permanent magnet, while the magnet that is connected to external circuit is an induced electro - magnet.
We have the arrangement in ,say (NorthPole-NorthPole arrangement), thereby they repel, but how to sense the change, for eg. in current change proportions etc.. ???
IS this above thing possible at all??
 
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Why not use a magnetic reed switch at the top and tap there to the uC?

Or are you tring to get the increments of the levels. I think that might be what you are after. Maybe switches on the inside of the tube? Bounce a signal off the top of the liquid from the top of the tank.
 
mrmmani22 said:
We need to get this for our project.. it's only a part of the project. This O/P goes to the microcontroller and so on..
So the question is..
1. Is such a thing avble commercially? OR
2. Can we design using circuits??
3. OR .. Can it be done this way??
**broken link removed**
From the figure, the magnetic float is a permanent magnet, while the magnet that is connected to external circuit is an induced electro - magnet.
We have the arrangement in ,say (NorthPole-NorthPole arrangement), thereby they repel, but how to sense the change, for eg. in current change proportions etc.. ???
IS this above thing possible at all??
the arrangment shown above will not work since u r using permanant magnets . if u need continous variation try considering flot type system.
or a transformer with moving core type design.
 
mramos1 said:
Why not use a magnetic reed switch at the top and tap there to the uC?

Or are you tring to get the increments of the levels. I think that might be what you are after. Maybe switches on the inside of the tube? Bounce a signal off the top of the liquid from the top of the tank.

I accept your suggestion .. yes What u r suggesting is like a magnetic proximity sensor provided here..
yes.. but then let's look at it realistically .. Say a 5 litre fuel tank.. How many reed switches can I keep atmost? probably 5 - 10 , I thought of something on lines of xx.x (Digital O/P) for fuel level .. Is that possible using the reed switches??
 
akg said:
the arrangment shown above will not work since u r using permanant magnets . if u need continous variation try considering flot type system.
or a transformer with moving core type design.
Can you enlighten me more on this topic, akg??
I'd love it ... Thanx!
 
off the shelf level measurment with switches in a tube with a floating ring magnet with varying switches per foot of tube, other ways are to use a capactance sensor but they are mostly on or off type of switch. a variable reluctance transformer with a float ( Dancer control ) or just use a weigh type system for a linear sensor output.
joe
 
mrmmani22

What you are proposing will not work, two permanent magnets will not do anything very much in a fairly static situation like a fuel tank.

Something similar has been discussed here some time ago, the idea was to use reed switches in a tube and have a floating magnet around the tube operating the switches.
Here is a link to that thread:
https://www.electro-tech-online.com/threads/pic-programming-program-construct.17820/

Have a look and see if that give you any ideas.

JimB
 
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Just salvage a float one from a car dump. Most use a float arm with a potentiometer to judge fuel level.
 
There is a common type of sensor that is just a metal rod going into the tank. You measure the capacitance by using it as the timing capacitance for a 555 and count the frequency output.

It doesn't work with water, only fuel. The presence of alcohol in fuel (a common blend is 10% nowadays) will throw off the reading substantially though.
 
hi
BMW coolant level sensors are constructed with a floating ring which has a magnet and actuate a reed switch which is in the middle of the assembly. They are easily available from any decent auto parts store.
 
I still like your original idea. Just add magnetic reed switches in the rod and feed them to a micro-controller. Simple. Affix magnet to the float, and let the switches signal the micro by tripping as it goes up and down.

I am going to look at the liquid alarm IC scorpioz mention..
 
Some boats use a sender with a lot of magnetic reed switches and a resistor in series between each one. The switches close the circuit at whatever level using all resistors from the top down to that level. Low resistance at top, high at empty having to go thru all resistors.
 
ClydeCrashKop said:
Some boats use a sender with a lot of magnetic reed switches and a resistor in series between each one. The switches close the circuit at whatever level using all resistors from the top down to that level. Low resistance at top, high at empty having to go thru all resistors.

Can you explain this idea please?
 
strokebow said:
Can you explain this idea please?
The reed switches are placed across the resistors, which are in series and act as a voltage divider. The level is read as an analog value; if all the switches are open, the resistance is high so the output voltage is low. If all the switches are closed, the resistance is low and the output voltage is high.
 
BeeBop,

How's the magnet arranged on the boat version? If it were a donut magnet on a float, as shown in the first sketch, you would only close one, or maybe two reeds at a time as it progressed up the tube.

Ken
 
KMoffett said:
BeeBop,

How's the magnet arranged on the boat version? If it were a donut magnet on a float, as shown in the first sketch, you would only close one, or maybe two reeds at a time as it progressed up the tube.

Ken

I never gave that much thought, but yes, it would only close one or two, so you would have to design the voltage divider so that each resistor, when shorted, would give a different value.

I should never make posts while drinking the first coffee of the day!
 
There is a similar discussion on:

https://forum.allaboutcircuits.com/showthread.php?t=9053

Someone mentioned reed switches and quadrature encoding. Two parallel strings of reed switches, with the switches soldered end to end. One string offset by half the length of a reed. As the magnet rode up and down the strings it might output sequential pairs of open-closed conditions that could be read as quadrature signals. A µC would have to store the last position, since this is not an absolute encoder. And you would need a reed and a reset button to indicate a full tank position. Not to sure it is too great an idea for a tank level gauge but it might have a use somewhere :)

Ken
 
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