Sorry to hear of your loss. I've been doing a lot of thinking on this one. Need to prevent the car from being driven, and prevent it from being towed. To prevent it from being driven a simple interlock on the fuel system or ignition system will suffice. An alarm system will put a time clock on a thief.. make it so he doesn't have enough time to figure out the interlock. Another way to do this is to allow the car to start, then shut down 30 seconds later or so. Mentally, he is prepared for the "getaway". When the car ceases to run, he should be prone to abandon it (probably out on the street). To prevent it from being towed, I have always liked the valve in the brake line trick. Apply the brake very hard, then the valve closes locking the brakes on. Can't tow it if it doesn't roll. This will also prevent it from being driven. I've often thought about using an RF transponder to let the car know you are the correct person, and to deactivate the anti theft systems. That way, a thief cannot watch you to see how you disarm the alarm / interlock system. Scott F. Touchton Lawrence Lile cc: Sent by: pic Subject: [PIC]: Practical car theft schemes microcontrolle r discussion list 10/22/01 10:29 AM Please respond to Lawrence Lile I'd like to re-open the topic of practical car theft prevention schemes. This is a hot topic for me, as I had a nice, fancy, almost new and one month old car stolen right out of my driveway this weekend. Burns me up. Without devolving into the underseat-knives-on-solenoids or high voltage steering wheels silliness, I'd like to figure out how I'll modify my next car so it can't be stolen, without spending big bucks, Here's some ideas: 1. Interrupt the line to the starter solenoid with a switch or relay. Either hide the switch in a wierd spot accessible to the driver, or connect it to a coded keypad. 2. Is there an electronic way to disable an automatic transmission? Some solenoid that engages something that could be disabled? 4. Disable power to the distributor with a special switch. 5. Disable power to the electric fuel pump. 6. Affix a 555 driven transistor to the horn and stereo and activate it if the driver doesn't enter the secret code within xxx seconds of starting the car. Now obviously, a real pro could defeat this stuff, but we're probably not going to stop a pro anyway. My car was not locked, and some kid probably tried a few car doors, found one open, jumped in, drove it down and pushed it into the river, or sold it to a chop shop. -- Lawrence Lile Sr. Project Engineer Salton inc. Toastmaster Div. 573-446-5661 Voice 573-446-5676 Fax -- http://www.piclist.com#nomail Going offline? Don't AutoReply us! email listserv@mitvma.mit.edu with SET PICList DIGEST in the body -- http://www.piclist.com#nomail Going offline? Don't AutoReply us! email listserv@mitvma.mit.edu with SET PICList DIGEST in the body