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Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.7.0 MIME-Version: 1.0 In-Reply-To: Content-Language: en-US X-Provags-ID: V03:K1:CgW8fVZGC1UoXVCZ+IzV4S++P4law9F1Tz3wl5pDbO40FWoZuzX S0W/cGWyIWJmJinbRWHiG1UGpEUjmrGyBD5YwIyV/FXGtT3zQHFZMokYUE6L5Ne6X20lRbA wWkhp4tI+yiirGzyoeTmOKUBNvjIaM6js9BaKLN3WUy9oC3QTmJxKVHmLoA5Hhi+knMBxtE 5oxs1LwcXmIT0Qf8XMFwQ== X-UI-Out-Filterresults: notjunk:1;V01:K0:pkZPmrqzmdE=:QrHmoGpDhOUBaq7ol8Y+l9 oHS9T/VeatiOTBEcb1fTm0uWQ61q2t8G+CFlgC7XSEpeXzVwmai52Cy5yh3ANkCilpBg0VQRk HYLNlPJf9lvwGuQ6kjQPuZybsRzMdD0erSGYFLnu7UMXUNjs1XuUfGcJZ9EYbGWQ+kPbd36eo WvwvyuG7yAqoP7YJ62YS4hfbSH+DCRC0zAk4jUjXd4o3nu3BkLHrUUFire+FOlWyzkrXZmT5R oqxnd00fumQMybphuqBLudaigDrhTmKuLx0PRTuhxz85S7vIw+99maYl4nGqh8ZItcfq7ygTK vjfY+7y2Vz60WXXAGx3uwLxBnxybjRmVjCs7wyoEkNrlDKW+bAggSf7VIwLgGxJ9rcO5MNaov yVa/rXrvPhWrEniNjs9AfJ73+yYHfIJfU8LZ9H/PggUFYCq8lruo3CNhBKg2aU3bbIklg/voK KRgNLbCbvXt7h5aTce0IuTEvZiCCgagb1HQkSbCTicHRnm0hVAqfTJ++6tg+knP1qUrzntWYQ SnM750bL6/RV+mIN/lcs0U/VZFPYLQ2vDVPwJCI4jCDv5YojRxuq+hxRKLGLnDmRLzpPki/Ex N7hyMlpq0oRnfXRYp4UpCrjW9xnOPhMB6yAxbY17Gqp3ypAKEO3VB+THjwUNwnynQXhiq917t 2i0L0fcPNUH23bl6AmpNRkd4G18NV4fPfGYTde4mup09vE9kRODrMysn/7y1xk25cpPDQ3+RT qD7FFFtQzM+GkWxE X-Spam-Score: 0.0 (/) X-Spam-Report: Spam detection software, running on the system "relay1.thorcom.net", has NOT identified this incoming email as spam. The original message has been attached to this so you can view it or label similar future email. If you have any questions, see the administrator of that system for details. Content preview: I am still not sure whether I am using that equation correctly. Chris, if you will forgive me for tagging along on your post, I'm trying to get this equation sorted in my head. Put no faith in anything I say with regard to this! ;-) [...] Content analysis details: (0.0 points, 5.0 required) pts rule name description ---- ---------------------- -------------------------------------------------- X-Scan-Signature: 1e15d6d6179985f133b43d42d658878a Subject: Re: LF: How can you tell if a Class D amp output transformer is starting to saturate? Content-Type: text/plain; charset=utf-8 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 I am still not sure whether I am using that equation correctly. Chris, if you will forgive me for tagging along on your post, I'm trying to get this equation sorted in my head. Put no faith in anything I say with regard to this! ;-) Andy, could you please check me out on this? Let's use the case Chris asks about as an example. Suppose I want to calculate the maximum RMS voltage to stay out of saturation. The manufacturer of the core states its Ae (equivalent cross sectional area) is 1.58 cm^2. I believe that works out to 0.000158 m^2. F = 137000 I do not know if I should be using 4 turns or 8 turns for the primary. It's 4+4. I will assume 8. Vrms = 4.44 * 137000 * 8 * 0.000158 * 0.1 Vrms = ~77V Does that look right? As for practical application I have no idea what this means. The equation uses Vrms but we're talking about something closer to a square wave than sine wave. But then it's not really a square wave either... Paul On 05/03/2018 10:00 AM, Andy Talbot wrote: > By measuring the voltage across the winding using a scope, then > seeing what Bmax is using teh equation > > Vrms = 4.44.F.N.A.B > > F Hz     N turns   A core cross-sectional area in metres^2    B tesla > > If B works out higher than about 0.1 for a ferrite core, then you > are approaching saturation > > Andy > www.g4jnt.com > > > On 3 May 2018 at 14:46, Chris Wilson > wrote: > > > > Hello LF'ers > > In  say a W1VD power amp, or in general, how can you test if the > output transformer is > starting to saturate please? Thanks. > > http://www.w1vd.com/137-500-KWTX.html > > > > > -- > Best regards, >  Chris                          mailto:dead.fets@gmail.com >