Do a search for "passive infra red detector". You should be able to find a circuit using a dual element pyroelectric detector. Off the shelf detectors are going for something like SG$10.00 - $20.00 and come with various fresnel lens. Normal, long range, curtain, etc. Depending on how you mount the detector, type of lens and sensitivity setting, it could trigger when the sun shines into the room, a radiator turning on or a rodent paying a visit. Most detectors are pretty reliable and not prone to false triggering if you set it up correctly. Look at the leaflet that comes with it, it'll show the top and side views of the "beams" (they're actually detection zones). At 12:21 PM 2/27/01 -0500, you wrote: >I don't really know ... All I'd like to do is build a cheap but effective >"IR" detector that do not triggers with pets like cats ... > >Thanks > >----- Original Message ----- >From: "Justin Fielding" >To: >Sent: Tuesday, February 27, 2001 11:59 AM >Subject: Re: [EE]: Infrared Detector vs Pet > > >> I assume that you are talking about IRbeams (which must be broken to >trigger >> alarm) rather than a PIR detector (using a pyrometer). >> >> >> ----- Original Message ----- >> From: "Simon Ethier" >> To: >> Sent: Tuesday, February 27, 2001 4:07 PM >> Subject: [EE]: Infrared Detector vs Pet >> >> >> Hi, I'm wondering.. I heard in a publicity of an alarm company that they >> have an infrared detecter which can make the difference between pet and >> human (how, I don't know ... ok it don't really "make" the difference, but >> the IR won't react to a cat for exemple, but will react to a human) I >found >> this very cool, especially if you have pet at your house... >> >> I'd like to build something like that ... Do any of you guys know what is >> the trick ? Is it less sensitive ? Does it require a minimum of movement >> ... >> >> Thanks >> --- >> Simon Ethier >> sethier@justine.umontreal.ca >> ICQ 66019153 >> >> -- >> http://www.piclist.com hint: The list server can filter out subtopics >> (like ads or off topics) for you. See http://www.piclist.com/#topics >> >> -- >> http://www.piclist.com hint: The list server can filter out subtopics >> (like ads or off topics) for you. See http://www.piclist.com/#topics >> >> > >-- >http://www.piclist.com hint: The list server can filter out subtopics >(like ads or off topics) for you. See http://www.piclist.com/#topics > > > -- http://www.piclist.com hint: The list server can filter out subtopics (like ads or off topics) for you. See http://www.piclist.com/#topics