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Re: [TCML] [UPDATE] Tesla Coil Computer Interference



Hi Brandon,

Timely and interesting!

Just today I hooked up a laptop (battery-only power) and USB-connected
LabJack A/D data acquisition device to a photodiode to sense and average
(with a LabVIEW program) the light from the dummy load.  The USB cable to
the LabJack was the only cable leaving the laptop.  The photodiode and cable
to the LabJack is about 20" distant from the nearest HV node (the halogen
lamps), so I figured I was pretty well safe and isolated.

Running the dummy load, after about 5 seconds of correct operation,
something in the LabJack would lock up.  Shutting off the NST and unplugging
the USB cable rectified the problem, but the next time the gap and dummy
load ran, the same thing happened again.

The cable between the photodiode and LabJack is #22 stranded twisted pair,
about 3 feet long.  I found a ferrite toroid (1 1/8" x 5/8") in my stash and
looped the cable 3 times through the toroid.  Problem solved!!!  I removed
the toroid, problem is back.  The ferrite toroid definitely fixed it.  Good
stuff!  If I hadn't seen this myself, I wouldn't have believed it - thanks
for posting.

Regards, Gary Lau
MA, USA

On Fri, Sep 10, 2010 at 5:56 PM, Brandon Hendershot <
brandonhendershot@xxxxxxxxx> wrote:

> Alright, basically this was my problem; After installing Gary's Primary
> Coil (Simulator, Emulator, Substitute, Place Holder, etc.), whenever I ran
> the coil, my computer would start to scream a solid beep tone from the
> motherboard mounted speaker. Turns out that it would stop after about 30
> seconds and would act as if nothing ever happened after that.
> The coil was in no way grounded to green wire ground, nor did I use (or
> need) an RF ground.
> The coil runs on 120V/60 hertz (US).
> 0-140V Variac (Problems arose around 120V anyway)
> NST is 15kV 30mA.
> Terry Filter always attached.
>
> I bought some ferrite beads off of eBay for cheap, but they were of
> excellent quality (I'll post specs on those later). I placed 2 on the coils
> power cord, one at each end, about 1-2 inches from the ends. Same with
> computer's power cable. The rest (8 total) went to expensive appliances
> around the room.
> Now it works fine. No more freaking out the computer!
>
> Brandon
>
>
> On Sep 10, 2010, at 4:39 AM, Gary Lau <glau1024@xxxxxxxxx> wrote:
>
> > Hi Brandon,
> >
> > Could you please remind us exactly what the observed problem was, and
> where
> > (on what cable(s)) the ferrite's were placed?  It would also be useful to
> > know the basic specs (power level) of your coil, and what kind of RF
> ground
> > arrangement you're using.
> >
> > Thanks, Gary Lau
> > MA, USA
> >
> > On Thu, Sep 9, 2010 at 6:31 PM, Brandon Hendershot <
> > brandonhendershot@xxxxxxxxx> wrote:
> >
> >> Hi All,
> >> Just a heads up for anyone stumbling upon this in hopes to resolve their
> >> own problems; The ferrite beads fixed it. The snap around beads work
> great!
> >> Big thanks to whoever mentioned it!
> >> Brandon
> >>
> >>
> > _______________________________________________
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> > Tesla@xxxxxxxxxx
> > http://www.pupman.com/mailman/listinfo/tesla
>
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>
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