Return-Path: Received: (qmail 8783 invoked from network); 13 Jun 2001 21:45:37 -0000 Received: from unknown (HELO warrior-inbound.servers.plus.net) (212.159.14.227) by excalibur.plus.net with SMTP; 13 Jun 2001 21:45:37 -0000 Received: (qmail 23733 invoked from network); 13 Jun 2001 21:45:16 -0000 Received: from unknown (HELO post.thorcom.com) (212.172.148.70) by warrior with SMTP; 13 Jun 2001 21:45:16 -0000 Received: from majordom by post.thorcom.com with local (Exim 3.16 #2) id 15AINI-00033j-00 for rsgb_lf_group-outgoing@blacksheep.org; Wed, 13 Jun 2001 22:40:28 +0100 Received: from gadolinium.btinternet.com ([194.73.73.111]) by post.thorcom.com with esmtp (Exim 3.16 #2) id 15AINE-00033e-00 for rsgb_lf_group@blacksheep.org; Wed, 13 Jun 2001 22:40:24 +0100 Received: from [213.120.111.254] (helo=mud) by gadolinium.btinternet.com with smtp (Exim 3.22 #9) id 15AIMb-0000vA-00 for rsgb_lf_group@blacksheep.org; Wed, 13 Jun 2001 22:39:45 +0100 Message-ID: <004001c0f452$0943ae60$fe6f78d5@btopenworld.com> From: "G3YXM" To: "LF Group" Subject: LF: driver chips and keying. Date: Wed, 13 Jun 2001 22:44:33 +0100 MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1; format=flowed Content-Transfer-Encoding: 8bit X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook Express 5.00.2615.200 X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2800.1106 Precedence: bulk Reply-To: rsgb_lf_group@blacksheep.org X-Listname: rsgb_lf_group Sender: Dear all. Beware of keying any but the TC4426 chip... The non-inverting TC4427 has its two outputs overlapping as the volts drop below 12, whereas the 4426 develops a dead band between the two outputs when the Volts are low. This aids soft(ish) keying. What a combined inverting / non-inverting chip would do would probably be a combination of both! High-level keying of the supply with another big mosfet is my preffered system these days, you can tailor the envelope any way you like. 73. Dave G3YXM.