Toroidal Transformer Screening

On 7/20/2015 1:20 AM, Tim Watts wrote:
> On 20/07/15 03:15, John S wrote:
>> On 7/19/2015 9:14 PM, John S wrote:
>>> On 7/19/2015 8:13 PM, Robert Baer wrote:
>>>> Syd Rumpo wrote:
>
>
>>>>    OK, i will bite: what is Edward Current? and where do i get a
>>>> description?
>>>>    The quacker DuckDuckGo fails.
>>>>
>>>
>>> He is using the formal name rather than the nickname (Eddie).
>>
>> Oops! Should be Eddy.
>>
>
> I thought it was rather clever!

Me, too. I wish I had thought of it. In fact, I did and from now own 
it's mine.

John S wrote:
> On 7/19/2015 8:13 PM, Robert Baer wrote:
>> Syd Rumpo wrote:
>>> Hi
>>>
>>> Another magnetics question!
>>>
>>> I have a SMPS which uses a toroidal ferrite transformer. It switches at
>>> ~100kHz, works very well, it's not my design and I can't change it.
>>>
>>> However, it introduces noise at about 50kHz onto/into my electronics
>>> which causes a problem. After much experimentation, I found that putting
>>> an earthed screen around the transformer kills the problem quite
>>> dramatically. The screen must be earthed, and doesn't need to be
>>> magnetic.
>>>
>>> This is something I can do. I don't have much room but I guess that
>>> wrapping copper tape around its exposed enamelled wire will cause
>>> problems for Edward Current. Is there a rule of thumb for what sort of
>>> gap to leave between the windings and a screen? How quickly does the
>>> field drop off?
>>>
>>> (And yes, I know not to make a shorted turn.)
>>>
>>> Cheers
>> OK, i will bite: what is Edward Current? and where do i get a
>> description?
>> The quacker DuckDuckGo fails.
>>
>
> He is using the formal name rather than the nickname (Eddie).
   Thanks. Kissing cousin of Mister Justin Case..