Return-Path: Received: (qmail 9679 invoked from network); 26 Mar 1999 16:44:10 +0000 Received: from magnus.plus.net.uk (HELO magnus.force9.net) (195.166.128.27) by guiness.force9.net with SMTP; 26 Mar 1999 16:44:10 +0000 Received: (qmail 11647 invoked from network); 26 Mar 1999 15:59:17 -0000 Received: from post.thorcom.com (194.75.130.70) by magnus.plus.net.uk with SMTP; 26 Mar 1999 15:59:17 -0000 Received: from troy.blacksheep.org ([194.75.183.50] ident=root) by post.thorcom.com with esmtp (Exim 2.04 #3) id 10QYpW-0006pi-01; Fri, 26 Mar 1999 15:47:30 +0000 Received: (from root@localhost) by troy.blacksheep.org (8.6.12/8.6.12) id PAA28949 for rsgb_lf_group-outgoing; Fri, 26 Mar 1999 15:47:43 GMT Received: from post.thorcom.com (root@post.unica.co.uk [194.75.183.70]) by troy.blacksheep.org (8.6.12/8.6.12) with ESMTP id PAA28804 for ; Fri, 26 Mar 1999 15:34:37 GMT Received: from mb07.swip.net ([193.12.122.211]) by post.thorcom.com with esmtp (Exim 2.04 #3) id 10QYcZ-0006bR-00 for rsgb_lf_group@blacksheep.org; Fri, 26 Mar 1999 15:34:07 +0000 Received: from s-257519 (dialup43-4-15.swipnet.se [130.244.43.207]) by mb07.swip.net (8.8.8/8.8.8) with SMTP id QAA16434 for ; Fri, 26 Mar 1999 16:34:04 +0100 (MET) Message-ID: <000601be779d$f761b8a0$cf2bf482@s-257519> From: "Johan Bodin" To: rsgb_lf_group@blacksheep.org Subject: SV: LF: 137 Carrier Date: Fri, 26 Mar 1999 16:32:27 +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 4.72.3110.5 X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2800.1106 Sender: Precedence: bulk Reply-To: rsgb_lf_group@blacksheep.org Hello Rik and others. A selective voltmeter can be built using a gyrator. If you have "The LF Experimenters Source Book" (RSGB), take a look at the gyrator tuned VLF receiver on page 3.7. The gyrator is described in more detail on page 5.1. With suitable OP-amps (fast!), I guess that such a circuit can be useful as a QSB monitoring receiver on 137 kHz. 73 de Johan