I've been messing around with the ignition system on my old Ford 8N tractor for a while now and the stumbling block in any design has always been the points. So I decided to build a hall sensor switch, possibly an Allegro A3144, because I already have a bag of them. I made a PVC sleeve to go over the points cam and planned on drilling holes in the sleeve and epoxying in 3X2mm magnets at 90 degree intervals. The air gap could be anything but I was planning on about 1 to 2 mm. Now the stumbling block. Despite an intensive search I have yet to find the grade of the magnets that are best for this application. I have a few 8x3mm N52 magnets that I'm using for testing but these are so strong that the sensor triggers long before the magnet is in front of the sensor, so it's going to be impossible to get an accurate and consistent trigger point, they are just too powerful. Ferrite and ceramic magnets don't come in small sizes, just the neodymium ones. I have some 3x2 and 3x2mm N35 magnets on order for experiments, but I'm concerned that these will also be too strong. Anyone have any knowledge of hall sensors in real world applications that can steer me in the right direction?