Return-Path: Received: (qmail 2488 invoked from network); 18 Sep 2004 08:46:59 -0000 Received: from unknown (HELO ptb-spamcore02.plus.net) (192.168.71.3) by ptb-mailstore02.plus.net with SMTP; 18 Sep 2004 08:46:59 -0000 Received: from mailnull by ptb-spamcore02.plus.net with spamcore-l-b (Exim 4.32; FreeBSD) id 1C8auw-0006F4-6F for dave@picks.force9.co.uk; Sat, 18 Sep 2004 09:50:02 +0100 Received: from [192.168.67.3] (helo=ptb-mxcore03.plus.net) by ptb-spamcore02.plus.net with esmtp (Exim 4.32; FreeBSD) id 1C8auw-0006F1-3s for dave@picks.force9.co.uk; Sat, 18 Sep 2004 09:50:02 +0100 Received: from post.thorcom.com ([193.82.116.20]) by ptb-mxcore03.plus.net with esmtp (Exim) id 1C8arz-000LY6-6C for dave@picks.force9.co.uk; Sat, 18 Sep 2004 09:46:59 +0100 Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1C8arN-0002IC-VR for rs_out_1@blacksheep.org; Sat, 18 Sep 2004 09:46:21 +0100 Received: from [193.82.116.30] (helo=relay.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1C8arN-0002I3-KR for rsgb_lf_group@blacksheep.org; Sat, 18 Sep 2004 09:46:21 +0100 Received: from imo-m26.mx.aol.com ([64.12.137.7]) by relay.thorcom.net with esmtp (Exim 4.41) id 1C8arI-0007vQ-V5 for rsgb_lf_group@blacksheep.org; Sat, 18 Sep 2004 09:46:21 +0100 Received: from DL4YHF@aol.com by imo-m26.mx.aol.com (mail_out_v37_r3.7.) id l.9d.4dd8ec87 (16087) for ; Sat, 18 Sep 2004 04:46:08 -0400 (EDT) Received: from aol.com (mow-d26.webmail.aol.com [205.188.139.167]) by air-id10.mx.aol.com (v101_r1.4) with ESMTP id MAILINID104-3ed7414bf5d028a; Sat, 18 Sep 2004 04:46:08 -0400 Date: Sat, 18 Sep 2004 04:46:08 -0400 From: DL4YHF@aol.com To: rsgb_lf_group@blacksheep.org MIME-Version: 1.0 Message-ID: <19D5F636.76DDC2E8.00041B63@aol.com> X-Mailer: Atlas Mailer 2.0 X-AOL-IP: 80.144.76.13 X-AOL-Language: english X-SPF-Result: relay.thorcom.net: domain of aol.com designates 64.12.137.7 as permitted sender X-Spam-Score: 0.3 (/) X-Spam-Report: autolearn=no,NO_REAL_NAME=0.285 Subject: Re: LF: LF components ...more Content-Type: text/plain; charset=iso-8859-1; format=flowed Content-Transfer-Encoding: 8bit X-Spam-Checker-Version: SpamAssassin 2.63 (2004-01-11) on post.thorcom.com X-Spam-Status: No, hits=0.3 required=5.0 tests=NO_REAL_NAME autolearn=no version=2.63 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-Spam-Filtered: by PlusNet SpamCORE (v3.00) Hi Alan, from the days of repairing TV's I remember the permanent magnets on certain "coils" too. Guess they used this to distort the current waveform in a controlled fashion for the deflection unit. About the DC-bias winding: Sounds a bit like a "transductor" - ancient magnetic component, sometimes called magnetic amplifier. The basic idea was to control a strong AC current with a weak DC current. But I cannot imagine these are used in SMPSU's. About the slots in ferrite rods: Yes, they are used to reduce eddy currents. Especially in those high-permeability types which are more semiconductors than insulators (you can tell with an ohmmeter). I have a large bundle of them in my radio-direction finding antenna for VLF ;-) Regards, and have a good LF season, Wolf DL4YHF