Im starting to get tired of that "EMP"...
A true electromagnetic pulse can only be found in for example the explosion of an atomic bomb. If you were to in theory try to trigger an EMP you wouldn't get near anything if you used all the power running through new york city (even if running it through a tesla coil that generally becomes useless after a certain amount of discharges). Nonetheless be able to direct it.
It all depends on what you would call an EMP however, if you were to simply extract the magnetron tube (microwave, high voltage system) and plug it into a high energy source taking precautions that the user is properly shielded you could create a "weapon" capable of destroying computers, etc in not much time at all by creating induction in the relatively weak transistors which is a relatively easy process.
It would however also cook any living organisms in the vicinity.
It would also be difficult to shield the user as radiowaves naturally bounce of objects.
The US/UK military are about to begin using a "low energy" (high energy, low burst, whatever you prefer) version of it, it effectively heats the skin of approaching "mobs" making the nerves react but without making any physical damage. It is called the Vehicle Mounted Active Denial System (VMADS)
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Active Denial Technology uses a transmitter to send a narrow beam of 95-GHz millimeter waves towards an identified subject. Traveling at the speed of light, the energy reaches the subject and penetrates less than 1/64 of an inch into the skin, quickly heating up the skin's surface. The 95-GHz energy penetrates 1/64 inch into the skin and produces an intense burning sensation that stops when the transmitter is switched off or when the individual moves out of the beam. Within seconds, an individual feels an intense heating sensation that stops when the transmitter is shut off or when the individual moves out of the beam. According to reports, a 2-second burst from the system can heat the skin to a temperature of 130° F. At 50 °C, the pain reflex makes people pull away automatically in less than a second. Someone would have to stay in the beam for 250 seconds before it burnt the skin,
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Sorry :blush: Im not in a very good mood... St. Elmo's Fire is very beatiful to look at... (im not saying that you dont have a microwave weapon or a couple of tesla coils, all im saying is, please try to stay on this planet because a homemade (real) EMP is nothing more then a dream)