I have to detect a magnet with an Arduino for a personal project. I was wondering if using a magnetoresistor and detecting the current drop was possible. I understand that using a Hall effect sensor is the easiest method, but I wanted to know if it was possible. How would I integrate it in this case.
To detect a magnet it is useful to start by using a magnetic field detector. "detecting the current drop" is a step off the main path - unless you are actually trying to detect a current drop - if so, you should say so.
A Hall sensor does just what you want - and is available off the shelf at good
prices and with well defined characteristics - why would you not start there?
A GMR (giant magneto resistive effect) sensor measures change in magnetic alignment - also off the shelf. (vaguely closer to what you want)
A MEMS gyroscope and accelerometer package often incorporates a 3 axis magnetic field detector as a bonus, What's not to like?
A fluxgate sensor will probably do what you want.
Even a mechanical deflecting sensor (compass needle like) can be bought or built from scratch.
All have the advantage of availability and or working in a known way.
But and :-) - you can but magneto resistive sensors off the shelf - eg here - from Arrow