Re: Pocket EMP device with a disposable camera's flash?

sk8terg1rl wrote:

Jim Yanik wrote:

"sk8terg1rl" <sk8terg1rl_2006@xxxxxxxxxxx> wrote in
news:1162507221.737488.279580@xxxxxxxxxxxxxxxxxxxxxxxxxxxx:


Ancient_Hacker wrote:

sk8terg1rl wrote:

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.

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.

Can't you could just break the flashtube and effectively turn it into a
large resistor,

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.


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.

Better learn HOW the flashtube is triggered and how a xenon flashtube
works.

Hint;the flashtube IS the switch.


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.

The inductor is made with copper wire, which is rather conductive to say the least - thereby putting a short circuit across a capacitor which cannot charge in the first place.
As hinted perviously, the Xenon flash tube *is* the switch.
So if you want the capacitor to charge, and at some pre-determined time to discharge into the LC circuit, you will need to add a switch (hint: an SCR will do).
.

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