On 04/08/2017 07:09 PM, Gene Heskett wrote:
> On Saturday 08 April 2017 19:42:26 Jon Elson wrote:
>
>> On 04/08/2017 01:51 PM, Gene Heskett wrote:
>>> I need to go to tsc or somewhere, wallies maybe, and get
>>> me some of those 3 to 2 electrical adaptors as I just
>>> found my gigahertz sampler scopes 3rd wire ground pin is
>>> .2 ohms from a damned probe ground lead, so just hooking
>>> up a ground lead is making a ground loop. I may even just
>>> uncover the darned thing and see if I can find the jumper
>>> and cut it. What the hell were they thinking?
>> The problem with that is they used to have line filters with
>> huge caps to line and neutral, and you'd get knocked on your
>> rear if you touched a scope with an isolated ground and
>> anything else.  You could even get sparks off the ground clip.
>> Not sure your current scope has such a filter, but if so,
>> beware when using it isolated.
>>
>> Jon
>>
> That consideration has indeed crossed my mind, Jon, so before I make it
> permanent, that will be checked.  Those honking big line bypass caps
> have tossed me around a bit in the last 70 years. Not the most pleasant
> feeling...
>
> On the lcnc joint errors front, I unplugged the cat-6 and hdmi video to
> the monitor cables, pulled them out of the holes in the bottom of the
> box, and took them back to the pi from an overhead direction, putting
> 15" of air between the cables and the noise from the stepper drivers.
> It had, the last time I checked 15 minutes back, made 45 copies of
> lathe_pawn.ngc w/o a joint error. So I guess I go prowling about fleabay
> for a separate box to put whats now on the inside of the door in this
> too small a box.  If I close the door, the whole maryann will be too
> close to the noisemakers.
>
>
Yup, the noise produced by unfiltered stepper drives (or PWM 
servo drives) is a major problem.
VFDs, too, of course.

Jon

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