An EMP weapon requires explosives. I don't have a schematic, but the structure is co-axial: The core is a bar of hi-ex, say a metre long and 3cm diameter. Around this is a copper coil (uninsulated wire). The outer layer is an aluminium tube. construction ensures that the coil and the aluminium tube do not touch. Before detonation, there is already a current flowing through the coil, so there is already a reasonable magnetic field. The hi-ex is triggered at one end, so that the explosion travels down the device from one end to the other. The next few steps happen with a couple of milliseconds: As the explosion's wave-front expands, it pushes the coil into contact with the outer tube. This shorts out the coil, one turn at a time. As the explosion travels down the device, the magnetic field is rapidly "compressed" into fewer and fewer turns of the coil, until it eventually "bursts" out of the last few turns in a massively-amplified pulse. The pulse exits the device at light-speed, with enough energy to frag any unshielded electronics with a half-mile or so. Very shortly after, the explosion continues out of the device with all its usual force. UK security services went through a period of fear about these things - set one off in the back of a van in London, and billions of pounds of cash and shares would simply cease to exist, along with the collateral physical damage done by the actual explosion. Fortunately (?), it turns out that the engineering tolerances required to produce one make it hideously expensive (for non-national-military organisations), so it's far more likely that terrorists would use "ordinary" suicide bombers to cause damage, and hackers to wreck the computer systems.