Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!shadooby!samsung!cs.utexas.edu!oakhill!craig From: craig@oakhill.UUCP (Craig Shaw) Newsgroups: sci.electronics Subject: Re: Seeing in the dark (sort of) Summary: Watch out for sunny days Message-ID: <2663@sol.oakhill.UUCP> Date: 27 Nov 89 15:07:30 GMT References: <1018@ariel.unm.edu> Reply-To: craig@sol.UUCP (Craig Shaw) Organization: Motorola Inc., Austin, Texas Lines: 37 >Prices on infrared motion-sensor outdoor lights have dropped down to the >$15 (sale) level here in Albuquerque. >I ... took the controller apart to play with it. > ... >I'm convinced that we have here the basis for a hard-to-defeat (hard-to-de- >tect, even) space alarm. You have to have a unit which has a sense position >that isn't shut down in daylight... > ... >A modular motion-sensing switch, which ... > offers possibilities to me. >A sensor for wildlife photography, a coyote scarer, a portable trail or >road "eyeball",...the mind boggles. > ... >Think about it. What would YOU do with such a device? Tell the net. We're >listening.... I've experimented with such a beast, in hopes of concocting an outdoor detector, to inform me when someone comes into my yard or driveway. The unfortunate and insurmountable problem arises when it's partly cloudy outside. Every time the sun is covered/uncovered by a cloud the output is triggered. The sun can heat large areas very rapidly, and this looks like lots of motion to this type of detector. Mine generated false indications every few minutes on partly cloudy days this summer in Texas. Works fine at night though. I guess I'll have to use IR source and receiver in a fixed beam system. The big problems there are wiring it far from the house, and disguising it. If IR is used, lenses are a problem and alignment is difficult. With visible LEDs, it may be seen at night, unless a very low duty cycle pulse train is used. Sign me - Back to the Drawing Board. -- Craig D. Shaw - MCU Systems Design (512)891-2245 Motorola Inc., Austin, TX. Brought to you by Super Global Mega Corp .com