Received: from PCH.mit.edu (18.7.21.50) by mail.efplus.com (192.168.0.8) with Microsoft SMTP Server (TLS) id 8.3.485.1; Tue, 4 Aug 2020 04:06:06 -0700 Received: from PCH.MIT.EDU (localhost.localdomain [127.0.0.1]) by PCH.mit.edu (8.14.7/8.12.8) with ESMTP id 074Au4vq008901; Tue, 4 Aug 2020 06:56:40 -0400 Received: from outgoing-exchange-1.mit.edu (OUTGOING-EXCHANGE-1.MIT.EDU [18.9.28.15]) by PCH.mit.edu (8.14.7/8.12.8) with ESMTP id 074AtxBc008895 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK) for ; Tue, 4 Aug 2020 06:55:59 -0400 Received: from oc11exedge2.exchange.mit.edu (OC11EXEDGE2.EXCHANGE.MIT.EDU [18.9.3.18]) by outgoing-exchange-1.mit.edu (8.14.7/8.12.4) with ESMTP id 074AsWCZ004598 for ; Tue, 4 Aug 2020 06:54:33 -0400 Received: from OC11EXPO29.exchange.mit.edu (18.9.4.102) by oc11exedge2.exchange.mit.edu (18.9.3.18) with Microsoft SMTP Server (TLS) id 15.0.1293.2; Tue, 4 Aug 2020 06:55:40 -0400 Received: from oc11exhyb4.exchange.mit.edu (18.9.1.100) by oc11expo29.exchange.mit.edu (18.9.4.102) with Microsoft SMTP Server (TLS) id 15.0.1365.1; Tue, 4 Aug 2020 06:55:58 -0400 Received: from NAM04-CO1-obe.outbound.protection.outlook.com (104.47.45.51) by oc11exhyb4.exchange.mit.edu (18.9.1.100) with Microsoft SMTP Server (TLS) id 15.0.1395.4 via Frontend Transport; Tue, 4 Aug 2020 06:55:58 -0400 Received: from DM6PR08CA0039.namprd08.prod.outlook.com (2603:10b6:5:1e0::13) by DM6PR01MB4698.prod.exchangelabs.com (2603:10b6:5:62::28) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.3239.21; Tue, 4 Aug 2020 10:55:57 +0000 Received: from DM3NAM03FT009.eop-NAM03.prod.protection.outlook.com (2603:10b6:5:1e0:cafe::bc) by DM6PR08CA0039.outlook.office365.com (2603:10b6:5:1e0::13) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.3239.16 via Frontend Transport; Tue, 4 Aug 2020 10:55:57 +0000 Received: from mail-ed1-f68.google.com (209.85.208.68) by DM3NAM03FT009.mail.protection.outlook.com (10.152.82.114) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.3239.20 via Frontend Transport; Tue, 4 Aug 2020 10:55:57 +0000 Received: by mail-ed1-f68.google.com with SMTP id q4so26275974edv.13 for ; Tue, 04 Aug 2020 03:55:57 -0700 (PDT) From: RussellMc To: Microcontroller discussion list - Public. CC: "Reid, John (Oji Fibre Solutions)" , ApptechNZ , "hanimamiruthm@gmail.com" , RossGMail , "ken@elecsyn.com" Sender: "piclist-bounces@mit.edu" Date: Tue, 4 Aug 2020 03:55:18 -0700 Subject: [EE]:: Simple DIY TDR - Time Domain Reflectometer. Thread-Topic: [EE]:: Simple DIY TDR - Time Domain Reflectometer. Thread-Index: AdZqT0EkNgtr50fyQDelibfHllyihQ== Message-ID: List-Help: List-Subscribe: , List-Unsubscribe: , Reply-To: Microcontroller discussion list - Public. Accept-Language: en-US X-MS-Exchange-Organization-AuthAs: Anonymous X-MS-Exchange-Organization-AuthSource: TS500.efplus4.local X-MS-Has-Attach: X-Auto-Response-Suppress: All X-MS-Exchange-Organization-SenderIdResult: Pass X-MS-Exchange-Organization-PRD: mit.edu X-MS-TNEF-Correlator: received-spf: Pass (protection.outlook.com: domain of gmail.com designates 209.85.208.68 as permitted sender) receiver=protection.outlook.com; client-ip=209.85.208.68; helo=mail-ed1-f68.google.com; dkim-signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=mime-version:from:date:message-id:subject:to:cc; bh=lBrq5AsU38X0w4bc+I2czazrajor5NHlRQmrGQrmfoE=; b=Gy/cEmZhZzfzO7plPyxj2PxwJoSzGUzDXEgJicSxFeSYoAWwWMg0MLCd6uGPR7vTuX T0wVp0qSyXJj4epIj8EpB+d5gq0fkqQv0RGAGRXsCP5HRk48pSs3Wyu7OerkV21rbeNh ezwd5tidmdkhC6/AnPDlUu2XbSq/uDH+VqUQFME2ECbmIVZ5GhXbZOT6rCx/yMcYFZio p0IGKQCQ2y/TMajVV20BbretOKhwuPyG0usJGbMEDn1LmujKIFPsqf/WYc0VAC+FgNAl s4Grae8DKTjQDuLrGT+oymCtoANM8wx2nOrARLt97wxygp2loDHU/KMZldQJsHpPeJeg iwww== authentication-results: spf=pass (sender IP is 209.85.208.68) smtp.mailfrom=gmail.com; mit.edu; dkim=pass (signature was verified) header.d=gmail.com; mit.edu; dmarc=pass action=none header.from=gmail.com; errors-to: piclist-bounces@mit.edu list-id: "Microcontroller discussion list - Public." list-post: x-beenthere: piclist@mit.edu x-mailman-version: 2.1.6 x-received: by 2002:a50:ef04:: with SMTP id m4mr4412661eds.63.1596538555532; Tue, 04 Aug 2020 03:55:55 -0700 (PDT) x-topics: [EE] x-content-filtered-by: Mailman/MimeDel 2.1.6 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 There are a zillion TDR circuits 'out there' - I'm highlighting this one due to the good writeup, example images and references. It's about as good an introduction as you'll get to a simple and useful device. A TDR is used to determine characteristics of cables and to determine the distance of "features" from the test point. This may include shorts, opens, impedance discontinuities, taps, ... . A simple TDR typically applies a sharp "square" edge signal or a pulse to the cable and then observes the resultant voltage at the drive point - often using an oscilloscope. This TDR circuit uses mainly a 74AC14 hex Schmitt inverter IC. https://www.epanorama.net/circuits/tdr.html They say do not substitute the IC - but other versions of the 'C14 with lower drive levels and or higher propagation delays could still be useful. Russell _an --=20 http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist .