Re: Floating Scopes

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "davep by way of Terry Fritz <twftesla-at-qwest-dot-net>" <davep-at-quik-dot-com>

Tesla list wrote:

>Original poster: "Winston Krutsch by way of Terry Fritz 
><twftesla-at-qwest-dot-net>" <u236-at-earthlink-dot-net>

>Hi All (again)

>Thanks for your input.  Sorry for my sketchy information.

>What I meant was that I wanted to put the scope "in the

>donut hole".  The scope's signal ground is connected

>directly to the case, and I believe that the
>components' power ground is connected to the case too.
         Probably.  doing the 'sensor' to read current

         may get interesting.

         When doing this class of work, need to get used to
         the fact that at RF (and, so some extgent, DC)
         metal has an inside and an outside.  Stuff on the
         inside can't 'see' the outside.


>I just measured both the scope, and my toroids, and found

>that no matter how hard I pushed, I couldn't stuff the

>scope into the middle of any of them ;-(.  This may be

>good, since now I'll need to make a toroid specifically

>for this experiment,

         (semantic trivia:
         By Definition, a toroid has a hole in the middle.
         No hole, its called a top terminal or whatever.)

>and can design the needed features into it, rather than

>lashing together some crude thing.

         Means retuning the system.  8)>>

>I'll probably make a "toroid" without a hole in the middle,

>that has a removable chicken wire top.

         Think of an upside down metal wastebasket, with
         curvy bottom.  Such like have been used on
         van de Graaf machines.

>That way, the whole toroid becomes a faraday cage.

         A toroid IS a faraday cage, a curiously shaped one...

>Since the scope is only 8" high, 6" wide, and 14" long, I

>won't need a very big topload.

         Would it help to mount it tube up (or down?)
         and view the screen with a mirror?
         Just a thought.

>Also, should the scope's case (ground) be connected
>to the toroid/faraday cage when taking measurements (coil running),

         To the INSIDE, yes.
         (exactly how the current sensor gets done is tricky.)
         And fibering it down from a battery powered sensor,
         either as analog or digital (i'd start with analog...
         simpler... maybe...  either would take some checking
         to understand frequency response.)

>or should it be isolated?

         I'd say not: the sensor design may be tricky.  Might
         plan on some test runs with 'other things' to see if
         the 'grounding' is correct before putting the scope
         in.


>I'd think that it'd be nearly impossible to
>isolate it, considering the capacitive coupling involved.

>Anyhow, thanks for your advice, past and (hopefully) future.  This is
>an interesting venture, to be sure :-)).


         best
         dwp

...the net of a million lies...
         Vernor Vinge
There are Many Web Sites which Say Many Things.
         -me