Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!usc!zaphod.mps.ohio-state.edu!uwm.edu!linac!att!pacbell.com!ucsd!sdcc6!sdcc13!gbell From: gbell@sdcc13.ucsd.edu (Greg Bell) Newsgroups: sci.electronics Subject: Ideas needed for Car Alarm Arm/Disarm method Message-ID: <17748@sdcc6.ucsd.edu> Date: 24 Mar 91 01:55:58 GMT References: <5537@media-lab.MEDIA.MIT.EDU> <17745@sdcc6.ucsd.edu> Sender: news@sdcc6.ucsd.edu Organization: University of California, San Diego (bleck) Lines: 32 I need some ideas on an arm/disarm method for an auto alarm I'm designing for fun (80% built, actually). Here are the possibilities I've come up with along with their disadvantages. Does anybody have any idea how to overcome the disadvantages and/or any new possibilities? 1) One of those pre-made RF transmitter/receiver pair you can buy. I've heard of thieves using "scanners" to scan through all the possible digital codes. Also, what happens when the batteries die? You need two ways to arm/disarm with this setup. 2) A keypad mounted on the center console. The only problem with this is that if somebody breaks in and hacks the thing to pieces trying to shut the alarm off, I have no way of disarming the system when I get back! 3) A magnet sensor positioned somewhere "secret". But all somebody has to do to defeat this is watch me arm the system. 4) An IR transmitter/receiver pair. I've actually already built the transmitter onto a tiny board. But, again the problem with the batteries. Also I can't find a case small enough to house the thing. Many thanks for any ideas! -- ----------------------------------------------------------------------------- Who: Greg Bell Address: gbell@ucsd What: EE hobbyist and major Where: UC San Diego -----------------------------------------------------------------------------