Tiny GSM Alarm System

September 1, 2009 by 21 Comments

[youtube=http://www.youtube.com/watch?v=W746qoZsrEs]

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.

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RF Modem + 250mW Amplifier

April 2, 2009 by 37 Comments

rf

[Trax] sent in his writeup on this RF modem with built in 250mW amplifier. The original power of the RF transceiver was around 10mW, his final results after testing were nearly 250mW. He was able to to easily transmit data over 1000 meters using his test setup. He states that he was actually able to achieve this without an antenna on the receiving side. That’s pretty impressive performance. It’s also worth noting that he soldered all of the components in place using a home clothing iron and some soldering paste. That must have been fairly tedious.