Nice project!!
You make things MUCH neater than me.
This would likely pump a LOT of power into the coils, nice job.
For the people asking how "much gauss"
I would personally recommend taking the lazy man's route and use XY-MDS which is a complete circuit that replaces the OP's transistors.
You can get 2 of them for $6 bucks on Amazon.
https://www.amazon.com/NOYITO-Transistor-High-Power-Electronic-Controller/dp/B07D1W6VFS/
Makes the project one that anyone can do without even soldering.
Using just one of these I am getting 3000 microtesla
They could be combined if you need more power.
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