Im looking for a solution to have an analog gauge speedometer for a racing kart. Had my hopes on a cheap ebay tachometer, but that gauge is designed to use the ignition spark with many many volts. Pondering over the idea of a mechanical speedometer, but there arent any gearsets, that fit a 28mm front axle.
You can make a sensor by attaching a magnet to the axle and detecting revolutions using a hall-effect sensor (I believe that the correct device). Then you can easily time the revolutions and figure out speed.
I suspect that the vibrations in a racing kart make it a very harsh enviroment for any type of metering system with moving parts.
I have a bicycle "cyclometer" on the kart taking speed, but the radial speed of the magnet travel diamater (4,5") causes it to go haywire above 60 mph. Herkons ftw.
Im not very familiar with the whole hall sensor world. Where should I start as sensitivity is a concern.
plus, what does 5.65 degrees mean for arduino code? Travel-per-step?
You will have much better results using a hall sensor instead of the typical cyclometer reed switch.
Im not very familiar with the whole hall sensor world. Where should I start as sensitivity is a concern.
Mr Google will be of great help.
Much of what you do depends on how you can mount the magnet and the sensor.
There are small, strong rare earth magnets and you can read about them here. https://www.kjmagnetics.com/ They re available from many sources.
Regarding the Hall Sensor, the packaging and mounting options are important. I have used the Hamlin 55140's in several applications. Drew Hamlin
Most Hall sensors are rated for switching speed, (the 55140 is 10Khz) and you will need to figure out the counts for your geometry and speeds. They also come with different magnetic sensitivities and polarities, but i would think that if you can get the sensor to within 12-13mm (.5 inch) of a strong magnet you will not have to worry about sensitivity.