How to do a little EMP

That is of course true with the flux compression generator.
However, it has 3 disadvantages:
1. It gets way too strong quickly
2. You need explosives to build
3. It can only be used once, at least the tube and the coil (and of course the explosives) have to be replaced.

This is probably only about a small EMP, probably more for demonstration purposes.
It's not about killing all devices within a 1km radius ...
And as far as I know, such a flux compression generator is counted among the weapons of mass destruction. So that could cause trouble from the top
Besides, I don't think very few people want to tinker with explosives here. Especially since black powder is definitely not enough for such an EMP. You would need an extremely high detonation speed.
This can be achieved with certain explosives, which are also easy to manufacture.
But if you are serious about this, you should watch this video first ... swahl.html (I got it from another thread)
and then reconsider his decision.
So in short: Forget the project "I'll build my own flux compression generator" again very quickly!
I still think that a HV condi + coil is the best idea.
Possibly you can bundle the pulse with a parabolic mirror or something like that.

A line circuit breaker is not a switch disconnector.