(refer to diagram)
How to use it:
Set phone to vibrate. Add 12v. Leave for crooks.
When car is stolen, call or text lojack phone #.
lojack replies to predetermined phone # or email with coordinates.
Administer capital punishment to crook.
How I think it could work:
(If you don't already know, A phone vibrates by a unevenly weighted motor spinning. Power is applied to the motor, and it spins.)
Phone is opened and the motor is removed. The leads (possibly needing amplification) are then ran through the coil of a relay.
When phone is called or texted, phone thinks it's vibrating. Instead it closes the contacts on the relay.
When the relay is closed, it allows 12v to reach a pin on the microcontroller.
Micro... is constantly looking for voltage on that pin. When voltage is present, micro.. gets coordinates from gps dongle. (how?).
micro is preprogrammed with a phone # or email address, and the code to write a text message and send it.
Micro is connected to the phone where the data cable does. It's like serial, I think.
micro runs code, sends text.
Like I said earlier, I'm not a programmer, but I know a little.
I know a few websites that let you send a text message through the website.
So there is code to do it. I don't know how one would "port" the code to be stamp (or etc)friendly.
Zorro has done amazing things with phonecontrol. Including sending text messages. Maybe he can help with that part.
I also have no idea how one would get the coordinates from the gps.
I currently don't use gps, so I have 2 questions.
Can one gps dongle be used for this idea and normal direction finding, or two?
Does the gps have to be in sight? Will kinda hamper the secrecy of the device.