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Re: Tingles from power supply

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   Err...read what is inside the parenthesis....

Re: Tingles from power supply



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How much capacitance would you expect from say a 25VA transformer ?

Graham



Re: Tingles from power supply
On Thu, 12 Mar 2009 06:33:08 +0000, Eeyore

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  It varies with the type of transformer, and how the windings get laid
onto it, and the level of separation between them.

  Same rules for ANY capacitor, donkey.  Two "plates", which make two
area sizes, and one gap between them consisting of either polymers or
paper, or impregnated paper. A layer of windings looks like a cylindrical
plate.  Basic cap formula, physically speaking.

  This one reason why most transformers do NOT directly 'nest' the two
windings together.  Good magnetic coupling, but too much inter-winding
capacitance.

 Seperate them with transformer tape or paper, and the cap value drops
with near no loss in coupling.  Also, an isolation benefit is gained.

  And yes, you already knew this, you just are losing brain cells at too
high a rate.

Re: Tingles from power supply
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The transformers I've seen that are intended to provide isolation have
windings that are completely separate, such as this

<http://www.dse.com.au/cgi-bin/dse.storefront/49b8d2b804be08842740c0a87e0106ae/Product/View/M6672

where the top winding is the secondary, and the bottom winding is the
primary. The intent clearly being that there is no way that the two
windings will become electrically connected.

I would not expect there to be much inter-winding capacitance.

Sylvia.


Re: Tingles from power supply
On Thu, 12 Mar 2009 20:27:25 +1100, Sylvia Else

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 Seperation with fish paper (transformer paper)of a couple thousandths of
an inch, plus the mag wire insulation, plus impregnation, if any is quite
good enough, and can be a mere few thousandths total, and provide 6kV
isolation.  Transformer tape is also only a couple mils or so, and most
of these super small jobs are usually incorporating cheap elements like
paper and there usually is not large gap.

  Most are NOT made in the style you gave a link to.  Most are one
winding right on top of the other, and it makes no difference which one
is inside, and which is outside.  That has more to do with construction
ease.  That 'ease' changes as the turns ratio grows.  It is far easier to
wind a couple thousand turns of an HV transformer right on the bobbin
base to achieve nice, flat winding layers, and then add the primary onto
that.  Placing the larger wire size primary first makes for a very
'terrain' like winding layer on the small gauge secondary.

 These relatively low ratio devices though, can be found to have been
wound either way.  It is all a matter of maker preference as there is
typically no huge efficiency difference between the choices.If there is,
the most efficient method will always be utilized. With these step down
jobs, you will find most to be primary first.

Re: Tingles from power supply



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<http://www.dse.com.au/cgi-bin/dse.storefront/49b8d2b804be08842740c0a87e0106ae/Product/View/M6672

I see no tranformers there.

Graham


Re: Tingles from power supply
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<http://www.dse.com.au/cgi-bin/dse.storefront/49b8d2b804be08842740c0a87e0106ae/Product/View/M6672
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Must be one of them new fangled websites with expiring URLS.

Put M6672 into the search box.

Sylvia.

Re: Tingles from power supply



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<http://www.dse.com.au/cgi-bin/dse.storefront/49b8d2b804be08842740c0a87e0106ae/Product/View/M6672
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Ah those. Yes, very common at lower powers.

Graham


Re: Tingles from power supply
On Thu, 12 Mar 2009 22:45:33 +0000, Eeyore

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<http://www.dse.com.au/cgi-bin/dse.storefront/49b8d2b804be08842740c0a87e0106ae/Product/View/M6672
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 It was there before, and it was a TRANSFORMER, not a tranformer.

  Is the Donkey a T-girl?  Bwuahahahah!

  Must be a new way to SPAM folks.

Re: Tingles from power supply

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Do you mean a *real* Avometer Sylvia?  As in model 7 or 8?



Re: Tingles from power supply
On Mon, 09 Mar 2009 01:20:22 +1100, Sylvia Else

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  Use some common sense.  Oh, that's right, you do not have any.

 Look at how stupid your question is, and you will already have your
answer.

Re: Tingles from power supply



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Sounds typical.



Perfectly allowable under IEC60065.

I bet I even know which component's causing it.

Graham


Re: Tingles from power supply
On Sun, 08 Mar 2009 19:37:46 +0000, Eeyore

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 Since you cannot know exactly what type of dongle circuit is being used
(especially from that dumb twit's description), you cannot possibly know
what component you "think" is causing the problem you "think" exists.

Re: Tingles from power supply



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Dongle ? What dongle ?

A small wireless router is 99.999% likely to have a simple flyback SMPS and I
know EXACTLY which component is going to be doing it and could even tell you
where you'll find it on the PCB. I'll even hazard a guess its value is 2n2 (
type Y2 ).

Most likely like this with lots of safety and approvals marks on it.
http://uk.farnell.com/murata/de2e3kh222ma3b/capacitor-x12-2-2nf/dp/9527036?_requestid98%989

Stop exposing your arrogant ignorance.

Graham



Re: Tingles from power supply
On Sun, 08 Mar 2009 23:53:16 +0000, Eeyore

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  You're a goddamned idiot. ALL WJANs have EXTERNAL supplies in the form
of an outlet hung or floor placed "dongle".  If you are too many decades
behind to know what a dongle is, you have no business in this thread.
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  You are 100% incorrect.  What a small wireless router invariably has is
a DC jack for PS input and an EXTERNAL supply, which you have no clue as
to how it is constructed.

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 You already tried that "guess" horseshit, and it got you nowhere.  You
don't even know how modern gear is powered, much less anything about the
actual circuit.  You are pathetic, donkey fucktard.







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Re: Tingles from power supply



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That is the wrong word  to use. A dongle is an adaptor that enables use of
licenced software
that plugs into a PC port.
http://en.wikipedia.org/wiki/Dongle

What Sylvia had is commonly called a 'wall wart'.
http://en.wikipedia.org/wiki/Wall_wart

Now shut the fuck up.

Graham


Re: Tingles from power supply



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Just how MORONIC are you ?

The WLAN hasn't got a dongle.

Graham


Re: Tingles from power supply
On Mon, 09 Mar 2009 12:28:50 +0000, Eeyore

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 It has a dongle power supply, idiot.

  The word 'dongle' hasn't been used for security devices since WE ALL
quit using them nearly five years ago or more.

  You ain't real bright on modern computers either, retarded donkey.

Re: Tingles from power supply



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NO SUCH THING EXISTS.

GROW UP ! Hah that would be a challenge for you.

Graham


Re: Tingles from power supply
On Tue, 10 Mar 2009 01:59:51 +0000, Eeyore

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  An idiot that has a problem with proper punctuation tells others to
grow up.

 That's rich.  Come back when your IQ exceeds 25.

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