Hey guys, I heard a tale about someone successfully building an improvised pocket EMP device that fried RFID tags. IIRC he apparently removed the flashbulb and replaced it with a simple LC tank circuit.
Do you guys think this is feasible? Will this device fry all electronics indiscriminately, or only those which are tuned to receive at particular frequencies?
It would tend to kill primarily RF tags around the frequency that the LC thingy is tuned to.
Don't aid the shoplifters ;-)
...Jim Thompson
--
| James E.Thompson, P.E. | mens |
| Analog Innovations, Inc. | et |
| Analog/Mixed-Signal ASIC\'s and Discrete Systems | manus |
| Phoenix, Arizona Voice:(480)460-2350 | |
| E-mail Address at Website Fax:(480)460-2142 | Brass Rat |
| http://www.analog-innovations.com | 1962 |
I love to cook with wine. Sometimes I even put it in the food.
Don't aid Big Brother
martin
"Caution: RFID-Zappers don't comply with FCC rules."
Nope, can't do it that way. The xenon flashtube is directly connected across the main storage capacitor. It's triggered into firing by a high voltage pulse applied to a thin wire that's wound around the tube.
A LC circuit of course can't be triggered that way. I guess you could put the LC in series with the flashtube, so there's be a several amp pulse into it. But that's not going to generate much of a RF field.
Much better EMP can be done with public-domain designs, just use Google.
If only it were so simple.
Britain is slowly but surely turning into a despotic, Orwellian dystopia. Not that I will be doing anything, I hasten to add.
Britain: the most spied on nation in the world
Your life in their lens
'Big Brother society' fears
Warning over surveillance society
Can't you could just break the flashtube and effectively turn it into a large resistor, and "short circuit" the LC in what were its input leads? AIUI all you're really taking from the disposable camera is its capacitor, the means to charge it and the trigger to discharge it. All of which should work independently of whether you have a flashtube or LC circuit connected to it.
The other EMP devices I've seen require the use of some kind of vircator assembly. This means nasty explosives (and potentially a LOT of trouble) and it will be a highly visible one-off usage device.
Any other designs for innocuous devices that are reusable?
So? Don't jerk off in public ;-)
...Jim Thompson
--
| James E.Thompson, P.E. | mens |
| Analog Innovations, Inc. | et |
| Analog/Mixed-Signal ASIC\'s and Discrete Systems | manus |
| Phoenix, Arizona Voice:(480)460-2350 | |
| E-mail Address at Website Fax:(480)460-2142 | Brass Rat |
| http://www.analog-innovations.com | 1962 |
I love to cook with wine. Sometimes I even put it in the food.
It has less to do with the police catching legitimate criminals, than criminalising the innocent and acting with impunity.
For example, the police who recently murdered an innocent, restrained and unresisting man are back on duty (Rambo killed another guy today too) and they weren't even *tried*. If that isn't an indication of being above the law, I don't know what is.
It is easy for you to point fingers being a Yank where freedom is still somewhat valued but I extend a very warm welcome to you to come to Britain and see things for yourself.
Until then, please spare us your snide misinformed comments.
"sk8terg1rl" wrote in news: snipped-for-privacy@k70g2000cwa.googlegroups.com:
It does not turn into a resistor,it turns into an open circuit;a big air gap. You obviously do not know how a xenon flashtube works.
Better learn HOW the flashtube is triggered and how a xenon flashtube works.
Hint;the flashtube IS the switch.
-- Jim Yanik jyanik at kua.net
Frankly I was surprised the public debate to start this early (heard of it today on the BBC Worldservice). For many years now I believe the obvious destination of the path human society has taken - given no too great catastrophy interrupts that - is a zero privacy society. It is the only way things can work out and be accepted by most people - anyone can watch anyones activity at any given moment, no exceptions. I am not sure I am ready to live in such a society but then I doubt I will live long enough to have to... Under the score the change will be for the better, 0 privacy will also mean 0 lies, which may have a dramatic effect on progress etc. It is encouraging to see the English initiating the debate; trying to stop the technology from utilization will of course be futile, although it will take many years for things to settle.
Dimiter (in Seldon mode yet again :-) :-)
sk8terg1rl wrote:
Are the cameras anywhere but in _public_ places?
...Jim Thompson
--
| James E.Thompson, P.E. | mens |
| Analog Innovations, Inc. | et |
| Analog/Mixed-Signal ASIC\'s and Discrete Systems | manus |
| Phoenix, Arizona Voice:(480)460-2350 | |
| E-mail Address at Website Fax:(480)460-2142 | Brass Rat |
| http://www.analog-innovations.com | 1962 |
I love to cook with wine. Sometimes I even put it in the food.
It is not just about public cameras. It is also about carrying a mobile phone (how do you know what it is doing), electronic payments and other traceable activities, online activity, etc. etc., the list may be growing by the hour rather than by the day...
Dimiter
Jim Thomps> >
So turn off your phone when you're not using it. And don't make electronic payments or do "other traceable activities".
Then they'll start _following_ you because you are acting suspiciously.
When you _are_ using your cell phone, they already know where you are. The phone company won't be cheated out of a penny.
Don't the British authorities still need a warrant to enter your home?
Just because you're paranoid doesn't mean that they're NOT out to get you ;-)
Sheeeesh! Sounds like the Brits are raising a large crop of leftist weenies.
...Jim Thompson
--
| James E.Thompson, P.E. | mens |
| Analog Innovations, Inc. | et |
| Analog/Mixed-Signal ASIC\'s and Discrete Systems | manus |
| Phoenix, Arizona Voice:(480)460-2350 | |
| E-mail Address at Website Fax:(480)460-2142 | Brass Rat |
| http://www.analog-innovations.com | 1962 |
I love to cook with wine. Sometimes I even put it in the food.
OK, so if I understand correctly: the trigger pulse ionises the Xenon, which then becomes conducting and the main discharge from the capacitor follows.
Depending on the circuitry of the disposable camera, the capacitor's discharge is either controlled by a second switch, or simply by virtue of the Xenon becoming conducting.
If it is the former, no problem - that second switch simply needs to be triggered or replaced to bypass it.
If it is the latter, then replacing the Xenon with an inductance coil will cause the capacitor to discharge immediately after the trigger pulse is fired.
So in theory it should work; correct me if I am wrong please.
A slide down to a surveillance-fetish society is not inevitable.
People must simply realise that they must accept risk as part of freedom. Trying to be obsessive about security and monitoring to "ensure safety" will simply turn the society into a high tax-high spending Socialist dystopia with certain groups of society above the law and/or telling us what to do.
An example: I would rather have laws that enshrine our right to be armed and defend ourselves, than rely on cops to do that. I am the best guarantor of my security; not a 3rd party.
I think the way it works is that the xenon tube is always connected across the cap; the voltage builds up to several hundred volts, somewhat under the spontaneous flashover voltage for the flashtube and the flash unit is ready; then a trigger pulse is applied to make some ions in the tube. Those are accelerated by the high voltage field, collide with other atoms, make more ions, in an avalanche effect. The xenon has broken down, its resistance drops to a very low value, and the big current pulse ensues as the capacitor discharges. As he said, the tube itself is the switch. Then, when the current through the tube disappears, the ions recombine and you have an insulating tube again. If you replace it with a coil, you'll never build up the capacitor voltage in the first place. Putting your coil in series with the tube will give you a big pulse into the coil, but as they said, probably not enough to damage anything. The cap will only be holding a few joules of energy.
I found this through google:
-- John
Agreed 100% on that. My point is, however, that technological progress will inevitably bring with itself either a "zero secrets" society or something even worse than Orwells (after all, he wrote 1984, not 2084....). I can't help being an optimist, so I imagine it will be the former.... Notice that 0 secrets means 0 secrets, _no_ exceptions. This will actually be better than todays hypocritic mess - although it will take some development until we are ready for it.
Dimiter (still unable to quit the Seld> Didi wrote:
If you want to zap your own RF ID tag, simply place it inside the microwave oven along with your favorite pop corn...
It wouldn't be nice to zap someone elses...
Mark
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