Return-Path: Received: from rly-mb03.mx.aol.com (rly-mb03.mail.aol.com [172.21.131.161]) by air-mb01.mail.aol.com (v125.7) with ESMTP id MAILINMB011-cfb4afad3ff347; Wed, 11 Nov 2009 10:11:09 -0500 Received: from post.thorcom.com (post.thorcom.com [193.82.116.20]) by rly-mb03.mx.aol.com (v125.7) with ESMTP id MAILRELAYINMB037-cfb4afad3ff347; Wed, 11 Nov 2009 10:10:57 -0500 Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1N8EpK-0002mo-93 for rs_out_1@blacksheep.org; Wed, 11 Nov 2009 15:09:42 +0000 Received: from [193.82.116.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1N8EpJ-0002mf-SA for rsgb_lf_group@blacksheep.org; Wed, 11 Nov 2009 15:09:41 +0000 Received: from mail.gmx.net ([213.165.64.20]) by relay1.thorcom.net with smtp (Exim 4.63) (envelope-from ) id 1N8Eob-0006U0-UJ for rsgb_lf_group@blacksheep.org; Wed, 11 Nov 2009 15:08:58 +0000 Received: (qmail invoked by alias); 11 Nov 2009 15:09:34 -0000 Received: from p5DC427C4.dip.t-dialin.net (EHLO Clemens04) [93.196.39.196] by mail.gmx.net (mp071) with SMTP; 11 Nov 2009 16:09:34 +0100 X-Authenticated: #17214767 X-Provags-ID: V01U2FsdGVkX1/FvfB95ZnFOaJxw5WR75yjNeHga5dZuW8GeBKRF3 3t12JZFEsJTDSv Message-ID: <011e01ca62e0$fa406140$0201a8c0@Clemens04> From: "Clemens Paul" To: References: <001101ca621e$dcdc3380$96949a80$@princeton.edu> <20091110192309.4v8agotbs0k0gocs@webmail6.kuleuven.be> <004a01ca6249$d91531e0$8b3f95a0$@princeton.edu> <20091110222951.cr4qtrqagcwcowok@webmail6.kuleuven.be> <4AFAAE9C.1070304@ukonline.co.uk> Date: Wed, 11 Nov 2009 16:09:23 +0100 MIME-Version: 1.0 X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook Express 6.00.2900.3598 X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2900.3350 X-Y-GMX-Trusted: 0 X-FuHaFi: 0.58 X-Karma: unknown: X-Spam-Score: 0.0 (/) X-Spam-Report: autolearn=disabled,none Subject: LF: Re: Ferrite characteristics Content-Type: text/plain; format=flowed; charset="UTF-8"; reply-type=response Content-Transfer-Encoding: 8bit X-Spam-Checker-Version: SpamAssassin 2.63 (2004-01-11) on post.thorcom.com X-Spam-Level: X-Spam-Status: No, hits=0.0 required=5.0 tests=none 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-AOL-IP: 193.82.116.20 Peter, the best aid I know is the mini Ring Core Calculator V1.2 which is freeware http://www.dl5swb.de/html/mini_ring_core_calculator.htm It is a fantastic tool for known and unknown toroid materials. For determining the µrel of an unknown toroid you wind a few turns on it,measure the inductance,enter the inductance and the physical dimensions of the core into the program and it gives you all you want to know including µrel. And the results are really correct. Very handy with Amidon toroids,too. 73 Clemens DL4RAJ ----- Original Message ----- From: "Peter Dodd" To: Sent: Wednesday, November 11, 2009 1:31 PM Subject: LF: Ferrite characteristics > Does anyone know of a method of measuring the characteristics (permeability) of ferrite > cores? I have a box of these most without any identification although I do have T200, 68-2T > and T68-2s whose characteristics are known. > > It occurs to me that you can make a tuned circuit and measure resonance with a GDO when a > ferrite core is inserted into the inductance. A graph could be made of the different > resonances with different cores, to extrapolate the unknowns. > > However I think that ferrite bulk might be a problem. For example I guess the red T cores > use the same material but would there be a difference between the T200 and the T68? > > I have lots of material about ferrites in general - I just want to know what I have in my > junk box. I am not interested in exact measurements, I just want to know if a core is > suitable for a specific job. > > Regards > > Peter, G3LDO >