Re: Question regarding PCB board in close proximity with Primary Coil (DRSSTC)

["Tesla list" <tesla@xxxxxxxxxx>]

Original poster: Vardan <vardan01@xxxxxxxxxxxxxxxxxxxxxxx>

Hi,

You can actually directly power them from the primary.

Assume the voltage across the primary coil is 15kVrms and it is 50 
feet long.  That is 25 volts per inch.  If the LEDs run off 25 mA, 
just hook two wires to the primary 1 inch apart with a series 1000 
ohm resistor.  You have to run perpendicular though for a distance to 
escape the direct fields of the primary.  Of course, they would only 
light while the primary is energized in proportion to the current 
level.  You also should have a reverse diode in there.

Or, if you fiddle with it, you might run a stray LED with the two 
leads sticking out parallel to the primary at some distance to pickup 
the stray current.

The LEDs could also just go to small "loops" in the board to 
inductively pull the needed current.

More conventionally, you just have to avoid that full shorted turn 
and decouple the supply lines with "really good " caps.

If you really want to go for the engineering prize.  Make a many turn 
loop coil in the board to pick of the primary current and use the 
LEDs in the burden circuit.

Cheers,

        Terry


At 05:59 PM 5/7/2006, you wrote:
> Hi Dan,
>
> Your idea to illuminate the primary supports is novel.  A "modded" 
> coil.  Surely you can inductively power the led's from the primary?
> Just a thought...
>
>
> Karl
>
>
> On May 7, 2006, at 7:26 PM, Tesla list wrote:
>
> > Original poster: "Daniel McCauley" <dhmccauley@xxxxxxxxxxxxxxxxxxxxxxxxxx>
> >
> > Here is an interesting problem I am currently facing with one of my 
> > projects. Basically, i have a tesla coil with 6 primary 
> > polycarbonate supports which will be illuminated via LEDs (from 
> > underneath the base as shown in the attached image)
> >
> > Now, i would ideally like to use a PCB board to mount the LEDs and 
> > this PCB board would then screw directly underneath the base where 
> > the LEDs would protrude through the base and up into the bottom of 
> > the primary supports. This keeps everything nice, neat, and compaq 
> > with out having six million wires all over the place.
> >
> > However, the problem is that i am not quite sure how the board 
> > would act in close proximity with the primary coil which is only 
> > about 2-3 inches above this PCB board.
> >
> > Option 2 and 3 both seem to be the worse of the group since they 
> > will couple with the primary like a shorted or partial turn, respectively.
> >
> > Option 1 seems like a possible alternative, but i'm not sure how 
> > that would work. And Option 4 with the flying leads may be the only 
> > feasible option.
> >
> > Anyways, what are your thoughts on Option 1?
> >
> > Any other thoughts or ideas you may have???
> >
> > Again, my concern isn't how the PCB board would affect performance 
> > of the coil but rather it is the concern of induced noise onto the 
> > PCB board which would screw up the control voltage powering the LEDs.
> >
> > Attached image shows application and possible options for PCB board
> > http://www.easternvoltageresearch.com/led_question.jpg
> >
> > Thanks
> > Dan