Return-Path: X-Spam-DCC: paranoid 1480; Body=3 Fuz1=3 Fuz2=3 X-Spam-Checker-Version: SpamAssassin 3.1.3 (2006-06-01) on lipkowski.org X-Spam-Level: X-Spam-Status: No, score=-1.0 required=5.0 tests=BAYES_00,DNS_FROM_AHBL_RHSBL, FORGED_RCVD_HELO,SPF_PASS,SUBJ_RE_NUM 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 uAQADRKa032739 for ; Sat, 26 Nov 2016 11:13:27 +0100 Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1cAZvE-0003jn-S1 for rs_out_1@blacksheep.org; Sat, 26 Nov 2016 10:09:28 +0000 Received: from [195.171.43.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1cAZvE-0003je-J9 for rsgb_lf_group@blacksheep.org; Sat, 26 Nov 2016 10:09:28 +0000 Received: from smarthost01b.mail.zen.net.uk ([212.23.1.3]) by relay1.thorcom.net with esmtp (Exim 4.87) (envelope-from ) id 1cAZvC-00080l-3Z for rsgb_lf_group@blacksheep.org; Sat, 26 Nov 2016 10:09:27 +0000 Received: from [82.70.254.222] (helo=OfficeWin7.lan) by smarthost01b.mail.zen.net.uk with esmtp (Exim 4.80) (envelope-from ) id 1cAZvA-000Awf-Lu for rsgb_lf_group@blacksheep.org; Sat, 26 Nov 2016 10:09:24 +0000 Date: Sat, 26 Nov 2016 10:09:24 +0000 From: Chris Wilson Organization: Gatesgarth Developments X-Priority: 3 (Normal) Message-ID: <10910218891.20161126100924@chriswilson.tv> To: Andy Talbot In-Reply-To: References: <635074543.20161125135600@chriswilson.tv> MIME-Version: 1.0 X-Originating-smarthost01b-IP: [82.70.254.222] Feedback-ID: 82.70.254.222 X-Scan-Signature: 1c38f63d01970a2bf149f660c9cb2a37 Subject: Re[2]: LF: H Bridge power MOSFET based amps question Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 8bit 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 Content-Length: 1801 Status: O X-Status: X-Keywords: X-UID: 9555 Hello Stefan and Andy, Friday, November 25, 2016 Thanks for the replies, I see now how similar they are to an H Bridge in a SMPS, and I have also found some good info from the audiophile world on H Bridge outputs. And I see now how the Source and Drain naming would have occurred, it's down to the review of positive and negative current flow in light of better understanding of electron flow. I just wish I had got into this hobby when I was younger with a more receptive and retentive brain! Thanks again, i have an RFI question, but I'll start a fresh topic. Best regards, Chris 2E0ILY mailto:chris@chriswilson.tv > Forget my comments about gate resistors, you said for a non linear > (switching) design.  I was talking about linear amps > As the last post said, small values to damp oscillations if any are > needed at all - assuming a proper square wave drive, they shouldn't be. > 'JNT > On 25 November 2016 at 14:16, Andy Talbot wrote: > continuing... > The gate resistor just has to swamp teh Xc of the gate capacitance > in a linear amp, to make it look clean and resistive at the input.  > So, for example, assume 2000pF  Cgs at 475kHz.   Xc = 167 ohms.   SO > a shunt R of say 30 to 50 ohms will dominate.     > If you were really daring you might think it possible to resonate > out the Gate C and then get really high gain.   ( Don't do this with > an expensive FET).   But worth trying the experiment to see - power > oscillators take on a completely new meaning if you try it. > drain / source...   emitter / collector.  They're just legacy > names.  You just know what they are without thinking of the actual > meaning.   Although, I suppose, if you think of electron flow........... > 'JNT