<x-html><!x-stuff-for-pete base="" src="" id="0"><!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN"> <HTML><HEAD> <META content="text/html; charset=iso-8859-7" http-equiv=Content-Type> <META content="MSHTML 5.00.2014.210" name=GENERATOR> <STYLE></STYLE> </HEAD> <BODY bgColor=#ffffff> <DIV><FONT face=Arial size=2>Greetings! I'm interested in making an alarm system using PICs. I'd like to know what sensors are available in the market that could detect human presence. I'm interested in all kinds of them, even sound sensors. Is this stuff usually very expensive? Please let me know. Thanks in advance, Argiris.</FONT></DIV></BODY></HTML> </x-html>