DIY: Very Low Cost GSM Anti-Theft System


Thread Starter #1
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Hi all,
This is my upgrade to existing security system. After the project, my car automatically make a phone call to my mobile number when ever security siren turn on.

All you need....
YOUR CAR MUST HAVE ANY SECURITY SYSTEM TO DO THIS UPGRADE !!!!!

1. Old mobile phone with fixed dialing facility. (working)
2. timer relay (from ebey)
4. few meters of circuit wires

Idea.....
when the security system turns on... it supply continuous 12v current to siren. I bypass the siren power wire and use it to trigger the timer relay..... Then relay connect the fixed dialing key connectors of the phone..... and phone dial the number you want.

Steps
1. Identify the siren power wire or any other wire that supply 12v when siren turns on
2. use it as relay power positive
3. connect the relay power negative to vehicle body
4. solder the two touch area carefully (without connecting each together) with two wires
5. connect this two wires (4th step) to relay
6. Assign the fixed dial number to above key (4th step key)

I use earphone jack and jack base to connect the phone and relay. Then it is easy to unplug the phone for charging. Also I set phone "screen always on" in-order to use fixed dialing at any time.
 

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Varun560061

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Re: DIY GSM anti theft system - Very low cost

Neatly executed. Please put up more details like the wiring done.

Can we use an mobile charger with timer to charge the mobile.
BTW why is the timer relay used in this case.
 
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Very nice idea and very neatly executed.
But I have a query Will the cellphone not call you when the alarm chirps while locking and unlocking the door ??

@ Varun, a timer relay is used instead of simple relay to complete the circuit for 4 number key.
A 7805IC controlled circuit can be used instead of the battery. This will power up the cellphone 24*7
 
Thread Starter #5
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Re: DIY GSM anti theft system - Very low cost

Neatly executed. Please put up more details like the wiring done.

Can we use an mobile charger with timer to charge the mobile.
BTW why is the timer relay used in this case.
first i try with normal relay. when ever i use remote key my siren give one "beep" sound. it tiger the normal relay and press fixed dial key. (i assign number 9) and it display "9" on phone screen. i used old unbranded Chinese phone (but fake nokia name on the phone battery ). this phone can not activate fixed dialing facility when any number or # or * display on its screen. with timer relay we can delay the relay On time. (and it activate after 3 seconds in my case) then i can keep phone screen blank to facilitate fixed dialing.
some times other phones may work with normal relay
 
Thread Starter #6
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Very nice idea and very neatly executed.
But I have a query Will the cellphone not call you when the alarm chirps while locking and unlocking the door ??

@ Varun, a timer relay is used instead of simple relay to complete the circuit for 4 number key.
A 7805IC controlled circuit can be used instead of the battery. This will power up the cellphone 24*7
pls refer my reply to Varun about timer relay.

yes you r correct. I will try with 7805. then we can completely hide it under the dash board.
 
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Wow., wonderful idea. But for me, need some more images and info as I am a kid in terms of electrical in a car :)
 
Thread Starter #9
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Wow., wonderful idea. But for me, need some more images and info as I am a kid in terms of electrical in a car :)
first you of all you must find-out the main control unit of security system. usually is is black color box with many wire supply. just see my picture.
or check under the dash board while pressing remote door lock and unlock keys. you can here listen to whispering like "tik tik " sound (relay on of sound) from the control unit.
find the wire diagram sticker on the control unit and locate the wire for siren.
turn on the siren and test 12v supply with multimeter.
scratch the wire and connect a new wire that use to trigger the timer relay
 
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