How to make an EMP?

[evw2k]

My science fair project was to test different types of shieldings to see if they could properly block an Electromagnetic Pulse. My problem is producing the EMP. I have done lots of research on it and most of the ways are not practical and i found them from questionable sources. I have talked to a few people in person and they recommended trying a spark of some sort to pick up the distortion it creates on a radio. I tried an engine spark plug and a stovetop spark plug and neither worked. I was also told that pumping too much electricity into a small toy motor would create an EMP. This is probably what i will do. However, I would like to know if it is safe, where i would get the power for it, and how I could keep it at the same amount of electricity into the motor every time. Thank you.

[deleted-71487]

It's quite difficult to generate a sufficiently high intensity broadband short duration electromagnetic field that it could be called EMP. The amount of energy required makes it relatively unlikely that it could be done safely.

However, EMP is not fundamentally different from any other electric field, just with much higher bandwidth and power. Any kind of Faraday cage (look that up) will keep out EMP, even that produced by a nuclear explosion. The problem is that it also keeps out all other electromagnetic forces, which means it's not a practical way to shield things like communications devices that need to receive and/or transmit.

I don't know where you are located, but if you're in an area that gets frequent thunderstorms, lightning produces a reasonably powerful EM pulse.

A spark plug might produce something detectable if you use a high enough voltage, though most radios filter that kind of noise for somewhat obvious reasons (otherwise they wouldn't work well in a car). In any event, you'll have better luck detecting a spark using an AM radio, rather than FM (you could look up why this is too). You might have more luck making your own primitive radio (a crystal radio or something else kit-based), because commercial radios are not very susceptible. That would also be an interesting project by itself.

Anyway, lots of information can be found about EMP and shielding it by googling for "electromagnetic pulse". But you might have an easier time measuring other kinds of EMI (electromagnetic interference). There are large amounts of information available about this field in books and on the web.

[evw2k]

i tried the spark plugs on the AM radio but it didn't work. The microwave worked really well, but I just wanted the EMP to look legitimate instead of testing with a microwave. (It doesn't look very professional). I was planning on using the AM radio to pick up the disturbances, but i really wanted to have an "EMP" that looked somewhat legitimate.

[deleted-71395]

I also thought that a spark plug would work well, but oh well.

I did find the following book, Electronic Gadgets for the Evil Genius : 28 Build-It-Yourself Projects, which has a project called "Robotic circuit jamming EMP generator". I haven't seen the book, so I can't judge how hard of a project it is, but perhaps they have the book at your library or you can just order it from Amazon.com.
http://www.amazon.com/gp/product/007142 ... e&n=283155

[evw2k]

funny you mention that book. It is what gave me the idea for the experiment. However, the book is more of a joke book. I don't think that any of the things in the book actually work. Its kind of like the time machine in napolean dynamite.

[deleted-71395]

I looked at the excerpt on Amazon.com, and it doesn't seem like a joke; it looks serious and, from the little of the book that I saw, it seems that those are real projects that would work, although they are not for someone who doesn't know their way around a soldering iron. The reviews on Amazon agree.

Maybe the book is assuming too much pre-knowledge, so it just seemed like mumbo-jumbo?

[deleted-71360]

Keep it simple.

A good EMP generator for experimental purposes would be a dimmer switch for lights. When set at mid range, you should get a rather good buzz from a nearby radio.

For a simple detector, use a handheld portable radio tuned to the dead area between AM stations.

Once you have found a good shield, you should also notice that the radion does not receive other signals very well either, if at all.

Also, do a web search on the terms "tempest rf shield."

Robert Reavis

[evw2k]

Thank you. I don't think i can use the microwave unfortunately because it is already shielded to keep its electric charge from escaping into the kitchen. For the light dimmer thing, do i put the antenna near the light or the dimmer? Also, you say I don't need to set the radio to a station?

[evw2k]

I just tried the light dimmer and did the inbetween station. It worked wonderfully. Now I need to know if the disturbance is coming from the actual switch or the light. Thank you.

[deleted-71465]

I just tried the light dimmer and did the inbetween station. It worked wonderfully. Now I need to know if the disturbance is coming from the actual switch or the light. Thank you.

Good thinking. I'm impressed that you considered that the light might be causing the EM and not the dimmer. You should mention it in your experimental method write-up. The disturbance is caused by the switch itself. Here is a link to an article explaining it.

http://home.howstuffworks.com/framed.ht ... Switch.htm

To experimentally verify this. EM fields decrease in strength with the square of the distance from the EM source. That is to say the EM disturbance you get on your radio from an object that is 1 meter away is four times as strong as the disturbance you get if you move the radio only 1 more meter away (2 meters total). From this you should be able to simple bring the radio closer to the light and then the switch to see which gives you more disturbance.

[deleted-71360]

Well, almost correct. The dimmer causes the noise by turning the current on very suddenly at 120 times per second. The noise on the radio is the radiation the radio is detecting, but the source becomes the entire circuit. The wires, the dimmer, and the light bulb.

Hold the radio near the switch and them move along the path where the noise goes. You can trace where the wires go. (How to find hidden wires in the house walls and attic!) You shoud arrive at the light or the circuit breaker panel. Depending on the topography and wiring style in your house, the switch may be between or at the end. Branch circuits my carry the noise too, but probably to a lesser amount.

Do some research on dimmer switches and see how they make RF noise.

As far as shielding, try shielding the radio. Radios are easier to shield than houses. Try aluminum foil, metal screen mesh, and electrostatic bags (those grey things that some electronic parts come in). When you find a good shield, notice how radio stations may not be receivable either.

Another issue with an EMP is the version associated with catastrohic damage is the single event extremely high amplitude and short time duration version that a nuclear blast produces from atmospheric interaction. The dimmer switch produces a repetitive pulse that is very low in amplitude and is not going to hurt anything (not even the radio).

Robert Reavis

[bluedragontao]

I don't know if this would help, but I once read somewhere that if you create a large iron- core copper-wound electromagnet, and set up a large capacitor( such as a custom jar capacitor , or if you're lucky, a manufactured one) or several, and hooked it up to the electromagnet and a power source, it would create a sizable EMP. I'm not sure of the feasbility of this, but i'm going to try it. Of course, this may be an EMP Bomb, but i'm not sure of the power.

[deleted-71447]

This is more a question than a suggestion, but what about the EMR from a cell phone? I've noticed that my computer speakers hum when a call is coming in and the phone is located near the speakers. Is this comparable to an EMP?

[deleted-71254]

ChrisG,

No, your cellphone is creating EM interferance (ElectroMagnetic Interference). This is usually very narrow bandwidth radio transmissions. An "EMP" is ElectroMagnetic Pulse... which is a very short lived, but very broad bandwidth radio emission.

Sources of EMP can can include atomic bombs, lightning, sparks from tesla coils, down to very faint EMPs from static electric shocks at home.

I hope this has helped.

[deleted-71447]

Thanks!