Hurrah! I got hall effect sensors!

Finally I got 6 hall effect sensors at

http://www.libelium.com

My sensors are MLX90217 by melexis. I paid nearly 10 pounds each for the sensors
including shipping.

So I started to test my sensor with recommended circuit.




I used resisters 540k, 1W and a 10k potensiometer.
Then,I got a result.



First, the value was unstable without resisters, however after adding resisters, the sensor's value
start to show correspondance with magnet's north and south sides.
If I will show north, display show some value. And if it is south side, the value was zero.
So basically the sensor work well.

However, one dissapointment was that I can't get any between values which will suggest the strength of
magnetic value. Basically the sensor can deliver value of 0 or 1.
So I need to think about to show my exsistance of egg. Because I don't want to get a sound all the time.

I got an idea to solve the problem. That is using a sensor and buttons on each nests.
If there is nothing, sensors and buttons will not detect any values. So arduino will not make sounds.
But if an egg on a nest, buttons will detect some value. So tree make sounds.
Also when buttons are on, sensors can detect value of 0 or 1. So depending on these values, trees
play different sounds.

Now, I got an idea and parts which I can work with, so now I need to write a patch on Arduino!