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Article #1259Re: Tingles from power supply
From: FatBytestard
Date: Thu, 12 Mar 2009 09:12
Date: Thu, 12 Mar 2009 09:12
39 lines
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2694 bytes
On Thu, 12 Mar 2009 06:33:08 +0000, Eeyore <rabbitsfriendsandrelations@hotmail.com> wrote: > > >Robert Baer wrote: > >> Eeyore wrote: >> > Robert Baer wrote: >> > >> >> RFI? Think not; that voltage is about half the line, and is from >> >>capacitave coupling from primary to secondary (if transformer type). >> > >> > >> > I think you need to read up on modern wall wart type switchers. >> >> Err...read what is inside the parenthesis.... > >How much capacitance would you expect from say a 25VA transformer ? > >Graham > 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.
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X-Google-Thread: 112d1e,5985c699c60fb1f8 X-Google-Thread: 103407,5985c699c60fb1f8 X-Google-Attributes: gid112d1e,gid103407,domainid0,public,usenet X-Google-Language: ENGLISH,ASCII-7-bit Path: arc1-ca.pugleaf.net!g2news2.google.com!news1.google.com!npeer01.iad.highwinds-media.com!news.highwinds-media.com!feed-me.highwinds-media.com!post01.iad.highwinds-media.com!newsfe18.iad.POSTED!7564ea0f!not-for-mail From: FatBytestard <FatBytestard@somewheronyourharddrive.org> Newsgroups: sci.electronics.design,aus.electronics Subject: Re: Tingles from power supply Organization: somewheronyourharddrive.org Reply-To: FatBytestard@somewheronyourharddrive.org Message-ID: <42khr4heg3jng89aqjisiq2nuehjledrsj@4ax.com> References: <00b89736$0$7237$c3e8da3@news.astraweb.com> <00b89aa6$0$7280$c3e8da3@news.astraweb.com> <l-mdnUIjnsHPjCrUnZ2dnUVZ_hEBAAAA@posted.localnet> <49B719C4.4C0B7AEF@hotmail.com> <XemdnU0KI8knAyXUnZ2dnUVZ_sDinZ2d@posted.localnet> <49B8ACA4.E32CFFA9@hotmail.com> X-Newsreader: Forte Agent 4.2/32.1118 MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Lines: 39 NNTP-Posting-Host: 72.197.142.200 X-Complaints-To: newsmaster@cox.net X-Trace: newsfe18.iad 1236849154 72.197.142.200 (Thu, 12 Mar 2009 09:12:34 UTC) NNTP-Posting-Date: Thu, 12 Mar 2009 09:12:34 UTC Date: Thu, 12 Mar 2009 02:12:31 -0700