🚀 go-pugleaf

On Thu, 25 Jun 2009 06:44:42 -0700, John Larkin wrote:
> On Thu, 25 Jun 2009 16:31:09 +0800, TonyS <scarborofun@gmail.nspm.com>
>>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.
>>>>>
>>>> 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.
>>> 
>>> That's usually the best way to ground shields.
>>
>>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?
> 
No, which is precisely the reason to ground only one end of the shield.

Cheers!
Rich