> > Yeah, it would need amplification, that's 4 sure. I've noticed birds
> > don't seem to emit much IR ..................SNR wrt background IR is
> > quite high in winter
>
>Have you Googled for something like +murata +PIR ?
>
>A project of a couple of years ago involved using Murata piezo
>sensors to detect people in a room 10m away with a battery-
>operated micro. The sensors on their own are pretty limited to
>a lot of movement under metre but adding a Fresnel lens makes
>a huge difference. Amplification is TLC271s at low frequency/
>low current setting. As the unit had a timeout period after detection
>the V+ for the amps was supplied by a PIC pin. From memory the
>PIR part of the circuit used around 20uA. The range that needs
>boosting is at most a few Hz. I found that the simple circuit used
>was fairly insensitive to air movements. Common security light
>circuits I looked at were more complex and usually based around
>a quad amp like an LM324. Their complexity helps to prevent
>false triggering, but in our app that wasn't too much of an issue
>so we just went with amplication. PIRs themselves are pretty good
>filters anyway. The Fresnel lenses were got from a local alarm
>supplier. As only a narrow horizontal band of detection was
>needed it was found that using just a 15mm strip from the middle
>of the (originally 50x50) lens was sufficient. Be aware that lenses
>are available for particular applications - eg curtain, long range,
>short range etc - and you may need to optimise. And not all plastics
>are transparent to PIR so watch out for that. Some lenses found
>weren't intended for PIR
>
>I would expect that small furry animals don't emit much heat. Fur
>is, after all, a very good insulator. Have you considered something
>more sophisticated, eg a motion detector based around a camera ?
>A webcam and an IR spotlight would do. By comparing frames it
>should be quite easy (on paper) to detect a new object. Plus you
>get a picture of it. The resolution of the comparison could possibly
>be used as a filter to focus on a particular size of aminal. eg
>
>
http://home.earthlink.net/~apendragn/gbcam/
>
>or Google for "artificial retina"
>
>--
>
http://www.piclist.com#nomail Going offline? Don't AutoReply us!
>email
KILLspamlistservKILLspam
mitvma.mit.edu with SET PICList DIGEST in the body