Tiny GSM alarm system

We’ve covered this sort of thing before, but there is something to be said for the simplicity of this tiny GSM alarm system by [trax]. The alarm system is designed to send the owner a text message when a sensor is triggered. This alarm only works with Siemens phones, but it shouldn’t be too hard to find one.  The alarm is configured via a dip switch on the board and can also be armed and disarmed by text. The brains of this system is a PIC16F84A. The code and schematics are included at the bottom of the page.

[Thanks Dario]


  1. markii says:

    loaded with options on just 1 kb, cool!

  2. tjhooker says:

    for what you pay in cellular costs you can afford an actual security system.

    I did GPS over SMS once and scrapped it.

    • tom says:

      BS! you can get a tracfone that costs between $5-7 a month, how much does an actual monitored security system who will call you only and not the police cost a month and to install? Around a thousand plus probably a retardedly overpriced $50 or more monthly to monitor.

  3. googfan says:

    i dont see a microcontroller on that board…

  4. tomas316 says:

    If you check out the website, you’ll see the hidden microcontroller. Here’s a hint, its on the back!

  5. googfan says:


    no need to be an ass…

  6. Alex says:

    Well… no, not really. Stick a prepaid card in the alarm phone, those ten bucks will last you at least 20 break-ins. Then get a flat rate messaging option for your main phone, something many people have anyway these days.

  7. AK says:

    I thought of doing something similar for my motorbike. Some phones will keep the digits dialled on screen(before you press call) even while its asleep. all you have to do is hook up a quick and easy circuit to the close the green “call” button switch. If you use a prepaid sim it will cost £10 and last forever. type in your mobile number on the alarm phone and save the alarm phone’s number as a contact called “YOUR MOTORBIKE IS GETTING NICKED!”

  8. DJ-Q says:

    How easy/difficult would it be to achieve something similar to this WITHOUT the need for a mobile phone? I.e a microcontroller connected directly to a SIM card to send SMS an alarm?

  9. Rachel says:

    If the alarm is interfaced to a computer, it could send an SMS over email for free. Maybe a hacked eye-fi card…

  10. tz says:

    I like how it powers the phone, but on standby it can stay on for a long time, or just plug it in.

    But the interface to the one in opengpstracker is easier (the headphone jack is also a ttl uart interface) using a Motorolo C168i which is still available as of last month.


  11. towelhead says:

    I wunder if I can make a bomb with this

  12. blockhead says:

    i’ve been thinking about something like this but without using a phone. I was thinking maybe for a mailbox alert system.

  13. markii says:

    you can always use a GSM modem but it is more expensive than old Siemens phone…

  14. emcee says:

    i can’t see the code and schematics?where can i find it?thanks.

  15. markii says:

    the bottom of the page: the RED download button :)

  16. Mark says:

    Hey, I’m very interested in how you managed to do all that in the video. i’m trying to do something similar myself. You said that the code and schematic is at the bottom of the page yet i can’t find it, can someone point it out or send it to me? thanks

  17. Phil says:

    Any idea where I could purchase it already made, inside a box, plug & play ?

    Thank you

  18. Pranay says:

    I cannot see the code for the PIC. Have you removed it? And isn’t the setup compatible with any Nokia sets?

  19. Cenjuro says:

    I looked and overlooked the website, but the code and schematics are not included. If it’s impossible to put it available on the website, can you email me then?

    • Markus says:

      Look to the right of the title – there is an icon which says ‘More Info’
      Click on this and the project website link is named. it’s live as of today (April 2012)

      PS… Great tutorial, well done you’ve put a lot of work into this. Impressed! Thanks potential solution ideas on my projects.

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