Return-Path: X-Spam-DCC: paranoid 1170; Body=2 Fuz1=2 Fuz2=2 X-Spam-Checker-Version: SpamAssassin 3.1.3 (2006-06-01) on lipkowski.org X-Spam-Level: X-Spam-Status: No, score=-0.7 required=5.0 tests=BAYES_00,DNS_FROM_AHBL_RHSBL, RATWARE_GECKO_BUILD,SPF_PASS autolearn=no version=3.1.3 Received: from post.thorcom.com (post.thorcom.com [195.171.43.25]) by paranoid.lipkowski.org (8.13.7/8.13.7) with ESMTP id u23Fpvs0018432 for ; Thu, 3 Mar 2016 16:51:57 +0100 Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1abVQm-0003KG-M2 for rs_out_1@blacksheep.org; Thu, 03 Mar 2016 15:44:48 +0000 Received: from [195.171.43.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1abVQm-0003K7-Bp for rsgb_lf_group@blacksheep.org; Thu, 03 Mar 2016 15:44:48 +0000 Received: from mailfe07.swip.net ([212.247.154.193] helo=swip.net) by relay1.thorcom.net with esmtp (Exim 4.86) (envelope-from ) id 1abVQk-0001kt-IE for rsgb_lf_group@blacksheep.org; Thu, 03 Mar 2016 15:44:47 +0000 X-T2-Spam-Status: No, hits=0.8 required=5.0 tests=BAYES_50 Received: from [81.224.101.198] (account cxu-dcw-tyr@tele2.se HELO [192.168.1.3]) by mailfe07.swip.net (CommuniGate Pro SMTP 5.4.4) with ESMTPSA id 652998181 for rsgb_lf_group@blacksheep.org; Thu, 03 Mar 2016 16:44:44 +0100 To: rsgb_lf_group@blacksheep.org From: Johan Bodin Message-ID: <56D85BF0.90801@tele2.se> Date: Thu, 3 Mar 2016 16:44:48 +0100 User-Agent: Mozilla/5.0 (Windows NT 6.3; WOW64; rv:38.0) Gecko/20100101 Thunderbird/38.6.0 MIME-Version: 1.0 X-HELO-Warning: Remote host 212.247.154.193 (mailfe07.swip.net) used invalid HELO/EHLO swip.net - verification failed X-Scan-Signature: e09cca6d8e44a91eadbdfb3e1b8aec09 Subject: LF: Re: [rsgb_lf_group] Re: MF: DC-Bias [was: EbNaut] Content-Type: text/plain; charset=windows-1252; format=flowed Content-Transfer-Encoding: 7bit X-SA-Exim-Scanned: Yes Sender: owner-rsgb_lf_group@blacksheep.org Precedence: bulk Reply-To: rsgb_lf_group@blacksheep.org X-Listname: rsgb_lf_group X-SA-Exim-Rcpt-To: rs_out_1@blacksheep.org X-SA-Exim-Scanned: No; SAEximRunCond expanded to false X-Scanned-By: MIMEDefang 2.56 on 10.1.3.11 Status: O X-Status: X-Keywords: X-UID: 7189 But if the winding is bifilar, usually a twisted pair, then, from the core's point of view, it will look almost like a single wire carrying current in alternating directions. The core has no way of knowing that there are two wires instead of one so it will "see" a pure AC excitation. Am I missing something obvious? 73 de Johan SM6LKM cpaul@gmx.net wrote: Hi Markus, > Clemens, I think that saturation from DC-biasing would only be > a problem if the two transformer primaries (LP1 and LP2) were > wound on separate cores. On a single toroid, the flux from the > two DC currents should cancel. It would appear that the flux from the two DC currents will not cancel because they don't flow at one time. The current into the center tap alternates from travelling through one half of the winding then the other due to the push pull action of the FETs. 73 Clemens DL4RAJ