[ale] OT: Cell phone signal blocker

[Jim Kinney]

On Mon, Jun 22, 2009 at 4:17 PM, Mike Harrison<meuon at geeklabs.com> wrote:
>> I have heard that there are such devices available
>> (Europe?), although not legal in the US (FCC regs). There
>> are also plans on the web (I think you can check through
>
> they technically aren't legal.
>
> And while ya'll are playing high-tech, it's amazing what a tesla coil and
> a spark gap do to ANY radio usage. ;)
>
> Way back in my caveman medical equipment days they called them "diathermy"
> units when hooked to a large coil of wire. The RF would warm the patients
> deep muscle tissue for "physical therapy" and "bloodflow stimulation".
>
> They also shut off or fried anything not tube powered in the area,
> and made radio communications nearby impossible. Broad spectrum white
> random RF noise. :)

<snicker> I got paid a visit by the FCC for some gear I built in high
school. A nice pile of wire called an oudin coil (25k turns of #24
enameled overwrapped with 5 turns of flattened 1/2" copper pipe and
cored wiht a nice chunk of soft iron rod 3/4" in diameter) that was
lazily (me) unshielded will provide multiple KV for a home made X-ray
tube while simultaneously blacking out all radio and TV for about a 4
mile radius. The gentleman was very nice and explained the problem I
was causing and helped me brainstorm an appropriate shielding process
(it fit nicely in a metal paint pail).

He was not quite as happy to see me again when I was cranking up the
spark gap as part of a power supply for a nitrogen laser about a year
later. But again he did not clobber me with legal issues.

Nowdays, they just confiscate the problem and send the sheriff.
>
>
>
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-- 
-- 
James P. Kinney III
Actively in pursuit of Life, Liberty and Happiness