🚀 go-pugleaf

Fred Bartoli wrote:
> Joerg a �crit :
>> Fred Bartoli wrote:
>>> John Larkin a �crit :
>>>> On Thu, 25 Jun 2009 16:31:09 +0800, TonyS <scarborofun@gmail.nspm.com>
>>>> wrote:
>>>>
>>>>> John Larkin wrote:
>>>>>> On Wed, 24 Jun 2009 21:42:07 -0700, <castlebravo242@att.net> wrote:
>>>>>>
>>>>>>> "David L. Jones" <altzone@gmail.com> wrote in message 
>>>>>>> news:h8B0m.53620$FI5.3564@newsfe12.iad...
>>>>>>>> Check out a rather unusual phenomenon you can see on your 
>>>>>>>> oscilloscope in my latest blog (#14):
>>>>>>>> http://www.alternatezone.com/eevblog/
>>>>>>>> See if you can get it to happen on your scope!
>>>>>>>> I'll offer a free subscription to my blog for the best screen 
>>>>>>>> shot posted :->
>>>>>>>>
>>>>>>>> Oh, and the probe doesn't have to be shorted either.
>>>>>>>>
>>>>>>>> Have fun.
>>>>>>>> Dave.
>>>>>>>> -- 
>>>>>>>> ================================================
>>>>>>>> Check out my Electronics Engineering Video Blog & Podcast:
>>>>>>>> http://www.alternatezone.com/eevblog/
>>>>>>>>
>>>>>>>>
>>>>>>> When I worked a Century Data we had a problem with our new reel 
>>>>>>> to reel vaccuum column tape drive when ever someone would walk by 
>>>>>>> the drive when it was reading it would get data errors. The 
>>>>>>> problem was that the shield on the cable from the heads to the 
>>>>>>> preamp was grounded on both ends.
>>>>>>>
>>>>>>> Bob
>>>>>> That's usually the best way to ground shields.
>>>>>>
>>>>>> John
>>>>>>
>>>>>>
>>>>> IIRC head signals mostly went via twisted pair. If they had a 
>>>>> shield as well we would certainly not ground them on both sides.
>>>>>
>>>>
>>>> You *want* large amounts of high-frequency common-mode noise?
>>>>
>>>
>>> Probably. Lots of people don't understand this and I've seen this 
>>> kind of mistake (opened shield) recommended in lots of highly 
>>> regarded EMC books.
>>>
>>> But that's really nice for us. (Joerg?)
>>>
>>
>> Yeah! But shhht, don't spill the beans here, at least not until I am 
>> retired :-))
>>
> 
> I think I'll retired after you, but this kind of misconception is 
> sufficiently widely spread that we don't have to worry :-)
> 

Oh, I am not worried at all :-)

But I am concerned about what happens when guys like you and I are in 
their 90's, the hands are shaky, the mind ain't what it used to be and 
the senior living place doesn't allow a Tektronix mainframe in the 
rooms. The next generation doesn't have anough analog engineers.

-- 
Regards, Joerg

http://www.analogconsultants.com/

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