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, 29 Jun 2021 21:19:38 -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 15U3pjHD001290; Tue, 29 Jun 2021 23:52:39 -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 15U3phPV001287 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=FAIL) for ; Tue, 29 Jun 2021 23:51:44 -0400 Received: from w92exedge4.exchange.mit.edu (W92EXEDGE4.EXCHANGE.MIT.EDU [18.7.73.16]) by outgoing-exchange-1.mit.edu (8.14.7/8.12.4) with ESMTP id 15U3p5Wj020536 for ; Tue, 29 Jun 2021 23:51:43 -0400 Received: from w92expo33.exchange.mit.edu (18.7.74.45) by w92exedge4.exchange.mit.edu (18.7.73.16) with Microsoft SMTP Server (TLS) id 15.0.1497.18; Tue, 29 Jun 2021 23:50:20 -0400 Received: from oc11exhyb5.exchange.mit.edu (18.9.1.110) by w92expo33.exchange.mit.edu (18.7.74.45) with Microsoft SMTP Server (TLS) id 15.0.1497.2; Tue, 29 Jun 2021 23:50:59 -0400 Received: from NAM10-BN7-obe.outbound.protection.outlook.com (104.47.70.101) by oc11exhyb5.exchange.mit.edu (18.9.1.110) with Microsoft SMTP Server (TLS) id 15.0.1497.18 via Frontend Transport; Tue, 29 Jun 2021 23:50:58 -0400 Received: from BN6PR18CA0006.namprd18.prod.outlook.com (2603:10b6:404:121::16) by CY4PR01MB3239.prod.exchangelabs.com (2603:10b6:903:e5::8) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.4264.23; Wed, 30 Jun 2021 03:50:58 +0000 Received: from BN8NAM11FT038.eop-nam11.prod.protection.outlook.com (2603:10b6:404:121:cafe::a8) by BN6PR18CA0006.outlook.office365.com (2603:10b6:404:121::16) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.4264.19 via Frontend Transport; Wed, 30 Jun 2021 03:50:57 +0000 Received: from mai.hallikainen.org (74.208.193.200) by BN8NAM11FT038.mail.protection.outlook.com (10.13.176.246) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.4264.18 via Frontend Transport; Wed, 30 Jun 2021 03:50:57 +0000 Received: from mai.hallikainen.org (localhost [127.0.0.1]) by mai.hallikainen.org (8.14.4/8.14.4) with ESMTP id 15U3ouZD008212 for ; Tue, 29 Jun 2021 20:50:56 -0700 Received: (from apache@localhost) by mai.hallikainen.org (8.14.4/8.14.4/Submit) id 15U3ouXp008209; Tue, 29 Jun 2021 20:50:56 -0700 Received: from 70.177.184.232 (SquirrelMail authenticated user harold) by mai.hallikainen.org with HTTP; Tue, 29 Jun 2021 20:50:56 -0700 From: Harold Hallikainen To: "piclist@mit.edu" Sender: "piclist-bounces@mit.edu" Date: Tue, 29 Jun 2021 20:50:56 -0700 Subject: Re: [EE] HVAC filter efficiency and energy consumption Thread-Topic: [EE] HVAC filter efficiency and energy consumption Thread-Index: AddtZySVzbmkT5FDST2rZDkLxQPblg== Message-ID: References: <60DA6883.23190.2A016236@brent.eds.co.nz> List-Help: List-Subscribe: , List-Unsubscribe: , In-Reply-To: <60DA6883.23190.2A016236@brent.eds.co.nz> 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 mai.hallikainen.org designates 74.208.193.200 as permitted sender) receiver=protection.outlook.com; client-ip=74.208.193.200; helo=mai.hallikainen.org; dkim-signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=mitprod.onmicrosoft.com; s=selector2-mitprod-onmicrosoft-com; h=From:Date:Subject:Message-ID:Content-Type:MIME-Version:X-MS-Exchange-SenderADCheck; bh=LKPhKvhUS+bXriDhar0n0x7Mh5DCGZeCiFlRzt7pcp8=; b=DBywo5eb4rRJwzM5cqUUqxShzKgDdcYv6icnZkfpVZbhQGpAItzGpPgbdrNz0o+Wk5A/zUX5rBa6sV7VtXRrOP3GvjPucGCgfIPWpYUcdsFGc6BCGkS5euI72WFtr0qBsumBc6wctaAhqq3gReeofATpLDAxp8lyIuLV/ywTtkI= authentication-results: spf=pass (sender IP is 74.208.193.200) smtp.mailfrom=mai.hallikainen.org; mit.edu; dkim=none (message not signed) header.d=none;mit.edu; dmarc=permerror action=none header.from=mai.hallikainen.org; user-agent: SquirrelMail/1.4.22-5.el6 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-authentication-warning: mai.hallikainen.org: apache set sender to harold@mai.hallikainen.org using -f x-topics: [EE] Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 How about a simple airflow measurement using a self heating thermistor? https://www.te.com/content/dam/te-com/documents/sensors/global/te-app-note-= ntc-for-gas-flow-measurement.pdf Harold --=20 FCC Rules Updated Daily at http://www.hallikainen.com Not sent from an iPhone. --=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 .