what input pin is it using?

Yes still have a resistor pulling in the opposite direction to the sensor.

There are in fact two types of digital hall sensor, one which switches when it sees any magnetic field and the other that outputs one state when it sees a south pole and changes state not when the magnet is removed but when it sees a north pole.

Joes:
i disagree the car is normally a front wheel drive car, when slip is detected it will lock up the rear diff (as it doesnt have a centre diff) to transfer the power to the back wheels. in its original state the car will decide how much lock to put on by looking at the outside temperature, steering angles, throttle position, G force meter and overall speed. so this will be a simple system compared to the original

For that to make sense, the drive to the rear wheels must be very different to a conventional prop shaft and diff. Do you have a clutch in the prop shaft? (I remember there was a very nice hydraulically controlled one from Land Rover a few years ago.)

Maybe it's a posi?

For that to make sense, the drive to the rear wheels must be very different to a conventional prop shaft and diff. Do you have a clutch in the prop shaft? (I remember there was a very nice hydraulically controlled one from Land Rover a few years ago.)

yes it is a hydraulically controlled

i tride that sensor out to day and could not get it to work the way we discussed so i tock the 10K pull down resister out and put a pot in then tork the pot down to 1.3k and it did work but very tempermental
the sensor seems to work between 1.0-1.3k
what do you think?

Joes:
i tride that sensor out to day and could not get it to work the way we discussed so i tock the 10K pull down resister out and put a pot in then tork the pot down to 1.3k and it did work but very tempermental
the sensor seems to work between 1.0-1.3k
what do you think?

I think you need to find out for certain what sort of sensor you have and what sort of signal it outputs. Is it definitely a Hall effect sensor? I would have thought that an MVR sensor was more likely.

If it's a Hall switch then you use it like a manual switch/button.

I think you need to find out for certain what sort of sensor you have and what sort of signal it outputs. Is it definitely a Hall effect sensor? I would have thought that an MVR sensor was more likely.

how can i test to see if it is a mvr sensor?
mite be easier to just get a now one so we no what we have then somthing like this?
http://www.amazon.com/Inductive-Approach-Proximity-Sensor-Detection/dp/B004U4GCCW/ref=pd_sxp_grid_pt_1_0

but would be better in 5v

Joes:
how can i test to see if it is a mvr sensor?

If it's an MVR sensor then the sensor will be slightly magnetic and it will produce a weak alternating electrical signal when ferrous material is moved towards and away from it. The magnitude of the signal is determined by the speed of the movement. This type of sensor is commonly used to detect the position of an iron/steel toothed wheel.

Hall effect sensors are not magnetic but require a magnet in the part being sensed.

this sensor is very magnetic on the end so might be, is that easy to be used with the arduino or am i better off getting a hall sensor ?

i thought it must be a hall sensor as a lot of the cars had a hall sensor looking at a steel trigger wheel for the engine rpm, so i thought these might be the same but obviously not

Joes:
a lot of the cars had a hall sensor looking at a steel trigger wheel for the engine rpm, so i thought these might be the same

They probably are the same, but those other cars you're thinking of aren't using Hall effect sensors either.

You need to measure the voltage level over the range of speeds you need to support when the sensor is installed. You will almost certainly need to do some signal conditioning to take your variable voltage incoming signal and clean it up to a square wave.

so i will be easier to put some hall sensor on it like in link then?

It could be as simple as a magnet in a coil. When a gear tooth passes close across the axis of the coil it will induce current in the gear tooth (eddy current) and the coil, the latter which can be picked up as a pulse with strength in proportion to the speed of the gear tooth. Such a sensor would not be affected by dirt or wet the way an light and sensor would. Unlike a Hall sensor, it would not require any magnets placed on the turning wheel.

If it is, don't try feeding it directly to Arduino until you know what directions make +V and -V.

Why buy when you already have something that must work or the car won't?
Can you get a part # on the sensor? Maybe it would be in a shop manual for the vehicle.

ahh yes there is a pos and neg symbol just above the pins on the sensor that would explain why they are there so how do i intergrate that with the arduino?

trying to find out information about it is near enough impossible ans manufacturers keep that information to themselves

Joes:
so i will be easier to put some hall sensor on it like in link then?

I would have said that an MVR sensor is the best one for the job - that's why they are so commonly used for this. But you need to cope with the fact that the amplitude of the output signal varies with speed, so you need to apply some conditioning before you can pass it to your input pin.

i just looked on my altodata and that says 60rpm 65 mV ac min
does that mean much to you or any help?

We can Google a part number.

Joes:
ahh yes there is a pos and neg symbol just above the pins on the sensor that would explain why they are there so how do i intergrate that with the arduino?

trying to find out information about it is near enough impossible ans manufacturers keep that information to themselves

That would be in a repair manual even if it's just a company number.

There's a + and a -. Any other pins? The thing could be a package with built-in amplifier for all I know. But 60 rpm 65 mV AC... they wouldn't feed it AC yet + and - pins don't sound AC to me.

How about the make, model and year of the vehicle? There are automotive forums where the answer may be found as well.

no part numbers on it just have 2 pin's on it. it is only a very little thing so i dont imagine there is much in it. i am extremely tempted to say sod it and just purchase some after market hall sensors as the car is an early 1980's car and everything mechanical in the car is from an 08 plate vehicle so me fitting those sensors is broad as it is long to fit either or, probably easier to fit the after market ones as i havent got to try and find trigger wheels to fit the cv joints and drill out hub carriers to fit them. at least with the hall sensor i can just get it to look at the bolk heads on the inner cv joint.

You could try a Hall switch (security type, very cheap, very sensitive and reads digital) and a magnet with a toothed or holed steel/iron wheel between the two. Iron between switch and magnet should suck the field in. I'm just not sure how big a hole you'd need for enough field to get through, depending on the thickness of the wheel and how close the sensor and magnet are.

If you put 1 magnet on a shaft then you will get 1 pulse per turn and the rest of the time nothing. With a fast turning shaft it's probably all you need but otherwise maybe not.

ok thanks i'll have to have a play but now we are back to the original question how can i run 3 hall inputs as i can only have to at mo?