well I'm working on scoping the CAS right now. Interesting little device and rather simplistic. The key will be what the ECU actually does.
What I can tell you is that ith a magnetic stainless that I have near at hand here just letting the magnet pull the steel against the sensor will generate a 100 ohm change in the sensor. Just sitting here the sensor has a 560 ohm resistance. The moment the steel moves to hit the sensor it jumps over 600. Then immediately returns to 560. Now the issue becomes how I can accurately test this to prove what you need... the problem lies in the profile of the tooth has to remain the same and that the speed has to be held constant. Well those are two things that are near impossible for me to do at this point...
Which leads me to the critical point. Digital circuitry like would be interpreting the signal from the CAS only cares about one thing... crossing voltage. If the circuitry detects a 1 as being at 5V (a standard logic voltage) then if you get a 6 volt peak it could care less it's still a one. In fact you may be getting a 12V peak and it only needs a 5V peak. So you likely don't need to be concerned at all about the magnetic ability of the metal. If it is magnetic it will work. And if it doesn't... you can add a very simple amplifier that will cost you about 2 or 3 dollars and that will correct your signal. Hell I'll build it for you for free if you pay for the shipping
Also of note... I noticed that it would actually further generate a negative return in resistance in some cases that would result in an increased appearance of the signal.. in simple terms.. the faster something moves the not only does the signal level get bigger... but the 0 side of it gets even more 0 like.
Also, it doesn't matter which wire you hook up to what. So feel free to swap the red and green wires as you so please for fun and just because.... the car will never know the diff! (the third wire.. the black one is the shielding).
Lastly, in your particular case... if you need to amplify the signal further... or want to ensure that it works, simply have the sweeps of the pulley that you showed made steeper... a bigger drop off the lip. That will generate a greater pulse.
And... for the geeks in the crowd... I find it interesting that two different wave forms are being used... the american sensor plate will generate a sloped square wave... the aussie version shown before will generate a triangle wave. But the important fact is that it does help narrow it down that more likely than not both vehicles are using trailing edge triggering on the sensor... Playing with it more for just a second.. the resistance (and thus the voltage drop across the sensor) goes up as the metal comes in, and drop when it is pulled away. This is inverted to what the CPU would see... it would "read" a voltage from the sensor and thus if the voltage is being dropped across the sensor it would see a lower value at the input. So flip it around and the moral of the story is that as the metal comes in the computer sees a LOWER voltage, and then as the metal tooth moves away you see a HIGHER voltage. Then, looking at the aussie plate you are moving the voltage DOWN slowly by moving the metal in more slowly (by having the ramp up to the point) and then are having the sharp drop off which will generate an INCREASE in voltage.. MEANING, that the ECU is looking for positive pulses.. so VERY much amplifiable.. and positive trigger based... (assuming a voltage based source.. if it is current sourced which is unlikely, then it would be the reverse of all of the above)
So anyway... don't worry about the magnetic capability.. if it is magnetic enough to stick to a magnet you'll be fine.. just don't use aluminum
.
