---- START NEW MESSAGE --- Received: from cherry.ease.lsoft.com [209.119.0.109] by dpmail10.doteasy.com with ESMTP (SMTPD32-8.05) id A20A4340182; Fri, 30 Jan 2004 08:10:50 -0800 Received: from PEAR.EASE.LSOFT.COM (209.119.0.19) by cherry.ease.lsoft.com (LSMTP for Digital Unix v1.1b) with SMTP id <13.00CC4DCB@cherry.ease.lsoft.com>; Fri, 30 Jan 2004 10:51:00 -0500 Received: from MITVMA.MIT.EDU by MITVMA.MIT.EDU (LISTSERV-TCP/IP release 1.8e) with spool id 0499 for PICLIST@MITVMA.MIT.EDU; Fri, 30 Jan 2004 10:50:51 -0500 Received: from MITVMA (NJE origin SMTP@MITVMA) by MITVMA.MIT.EDU (LMail V1.2d/1.8d) with BSMTP id 1845; Fri, 30 Jan 2004 10:49:03 -0500 Received: from qmail2.baremetal.com [216.86.113.241] by mitvma.mit.edu (IBM VM SMTP Level 430) via TCP with SMTP ; Fri, 30 Jan 2004 10:49:02 EST X-Comment: mitvma.mit.edu: Mail was sent by qmail2.baremetal.com Received: (qmail 31756 invoked by uid 0); 30 Jan 2004 15:49:00 -0000 Received: from berkelium3.baremetal.com (208.184.111.62) by qmail2.baremetal.com with SMTP; 30 Jan 2004 15:49:00 -0000 Received: from ISLANDERS (cbshost-12-107-16-202.sbcox.net [12.107.16.202]) by berkelium3.baremetal.com (8.12.10/8.12.9) with SMTP id i0UFltPq027583 for ; Fri, 30 Jan 2004 07:47:55 -0800 References: <001b01c3e6ec$bd319740$0301a8c0@user88l53zxzyb> <02b301c3e6fb$2ee56070$1308a8c0@Daniel> MIME-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook Express 6.00.2800.1158 X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2800.1165 X-Scanned-By: MIMEDefang 2.36 Message-ID: <001101c3e748$97de84b0$5d65a8c0@ISLANDERS> Date: Fri, 30 Jan 2004 07:49:01 -0800 Reply-To: pic microcontroller discussion list Sender: pic microcontroller discussion list From: David Schmidt Subject: Re: [EE]: Challenge for keen minds To: PICLIST@MITVMA.MIT.EDU Precedence: list X-RCPT-TO: Status: U X-UIDL: 371856516 Are you trying to keep engineering/student types from defeating your gate counter? Or the general public? Reason I ask, is that if you have multiple sensors (3 qty reed switches, all in series, along the length of the gate, buried in the wood/tubing) and it is concealed so that they do not know how your device works (even bury your device into the gate so it is not visible at all), they are not going to figure it out. Engineers love figuring things out and will try to defeat your counter. Students usually have too much time on their hands and will try too. Trick is to hide all the guts so the gate looks completely normal, AND add multiple sensors over distances. Question, How do you prevent one person from opening the gate and letting in 100 people from that single opening? Or a person from climbing over? (false ceiling?) Dave > > 2) How to detect gate openings ? Well, if I use a regular reed switch, > > people will defeat it inserting a flexible magnet close to the sensor > before -- http://www.piclist.com#nomail Going offline? Don't AutoReply us! email listserv@mitvma.mit.edu with SET PICList DIGEST in the body .