Envelope-to: dave@picks.force9.co.uk Delivery-date: Thu, 26 May 2005 15:45:36 +0100 Received: by pih-mxcore11.plus.net with spam-scanned (PlusNet MXCore v2.00) id 1DbJc8-00050c-48 for dave@picks.force9.co.uk; Thu, 26 May 2005 15:45:36 +0100 Received: from post.thorcom.com ([193.82.116.20]) by pih-mxcore11.plus.net with esmtp (PlusNet MXCore v2.00) id 1DbJc8-00050F-0U for dave@picks.force9.co.uk; Thu, 26 May 2005 15:45:36 +0100 Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1DbJbj-0003N8-9Y for rs_out_1@blacksheep.org; Thu, 26 May 2005 15:45:11 +0100 Received: from [193.82.116.30] (helo=relay.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1DbJbi-0003Mz-UK for rsgb_lf_group@blacksheep.org; Thu, 26 May 2005 15:45:10 +0100 Received: from fmmailgate05.web.de ([217.72.192.243]) by relay.thorcom.net with esmtp (Exim 4.43) id 1DbJbg-0002By-Ge for rsgb_lf_group@blacksheep.org; Thu, 26 May 2005 15:45:10 +0100 Received: by fmmailgate05.web.de (8.12.10/8.12.10/webde Linux 0.7) with SMTP id j4QEix1f029994 for rsgb_lf_group@blacksheep.org; Thu, 26 May 2005 16:45:02 +0200 Received: from [217.248.191.144] by freemailng1801.web.de with HTTP; Thu, 26 May 2005 16:45:00 +0200 Date: Thu, 26 May 2005 16:45:00 +0200 Message-Id: <367832978@web.de> MIME-Version: 1.0 From: "Hans-Albrecht Haffa" To: rsgb_lf_group@blacksheep.org Organization: http://freemail.web.de/ X-SPF-Result: relay.thorcom.net: 217.72.192.243 is neither permitted nor denied by domain of web.de Subject: LF: off topics: Inverter 12V/-12V wanted from DK 8 ND Content-Type: text/plain; charset=iso-8859-1; format=flowed 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-PN-SpamFiltered: by PlusNet MXCore (v2.00) Dear Lowfers, for a cw-shaping circuit with an op-amp (second order key-klick filter by Jim Moritz) I need an inverter for the negative supply of the op-amp. It is not possible to choose an dc/dc-converter, as most of these devices operate at frequencies of 100 kHz...500 kHz, just where the receiver will run. So it is necessary to design an inverter with an transformer running at 100 Hz...500 Hz, what is a good frequency for laminated cores designed for 50 Hz ac. Effectivity may be low, as the circuit will draw only a few mA at voltages of -5...-12V, when powered at +12V. My current thought: Astable multivib followed by driver-transistor and an 230V/12V-12V-Transformer (the 230V ac-windign will not be used). After rectification and stabilisation an voltage of -4V...-6V seems to be feasable. Have You already done somthing similar? Any proposals warmly welcome. 55, Hans-Albrecht DK 8 ND cba ______________________________________________________________ Verschicken Sie romantische, coole und witzige Bilder per SMS! Jetzt bei WEB.DE FreeMail: http://f.web.de/?mc=021193