Welcome to this very simple GSM security system that notifies you when the contact has been broken by using a Modified Cell phone & a 3 Pin reed switch & Magnet.
Now if you would like to see the GSM door contact working then visit my You Tube page here.
In the schematic above you can see the Door is closed so the current from button 5 is passed to pin 3 on the reed so the cell phone will not activate the one touch dial.
Now if you would like to see the GSM door contact working then visit my You Tube page here.
Now in the schematic above you can see now the door is open so the flow of current from the cell phones button 5 is now flowing in to pin one then to pin 2 of the reed switch this makes the circuit and activates the one touch dial.
Please note it only takes about 2 seconds to activate the one touch dial on cell phones, When the door is closed the switch will go back to pin 3 on the reed switch.
Even if the door was closed again it will still make the call out
1) I was asked if I could design a very simple GSM security system that when a door is open it will activate a modified cell phone and make a call to the owner.
2) The design has to be cheap the only power to the devise was a solar panel that was used to charge the mobile phone up as this has to be a very simple set up I will use a 3 pin reed switch witch needs no power to work as it works from a magnet.
3). Now how the devise works is simple with a cell phone and a 3 pin reed switch I have designed it to be nothing more than a simple loop switch the 3 pin reed switch has a NO & NC contacts.
4). Now taking advantage of the NO & NC contacts of the 3 pin reed switch we can design a very simple GSM system that will only need power going to the mobile phone the reed switch needs no power and the devise can be used any where in the world as long as you have a cell phone signal.
5). Now here is how the devise works when the door is shut the magnet fixed to the door needs to be as close as possible to the reed switch when the door is shut the reed switch is in the NO contact position.
6). Now as the reed switch is in the NO contact no current can flow from the contact on the cell phone so the signal is not sent as soon as the door is open the magnet can not keep the switch in the NO contact position, Now it becomes a NC contact so the current from the out side pad from one contact will connect to the inside contact and activate the mobile phones one touch or speed dial for the number locked in that number pad.
7). The idea is like using a relay but as we don't want to power a relay as well we can get around this and use a 3 pin reed switch.
8). You can see from the above photo how simple this is to build the devise is simple to build and set up and it can be built at low cost the only thing you need to buy is a Cell phone opening kit and a 3 pin reed switch.
9). You can buy a cell phone opening kit on Ebay Click here. or look on Ebay in your own country most cell phones use a Torx Screwdriver contact.
10). You will need to buy one RI-90 MICRO ATE change over reed single pole SPDT switch order this from here.
11). You can get a simple door magnet that is used in security systems go for the version below Click here.
12). When you come to modifying your cell phone first turn on the one touch or speed dial then put your mobile number in the number for that speed dial like number 5 on your mobile..
13). Now Open your cell phone up and solder one wire to the inside pad of button number 5 and solder the second wire to the outside pad of number 5.
14). Now put the plastic case back on with out Putting the rubber contacts numbers on or the cover that covered the circuit.
Here is a close up of how to solder to the in side-pad and out side-pads.
The wire from the inside pad must not touch the outside pad.
Please note if any one needs any help please do e-mail me here: Anthony@anthony-dacko.net