Before the inception of smartphones, people used the old keypad phones that were very sturdy and offered tremendously long battery life. In the last decade, Mobile technology has evolved at a rapid pace and everyone now use a smartphone leaving the old phone on its fate. Have you ever wondered what can be done with an old mobile phone probably still lying somewhere in your junk drawer gathering dust?

In this Instructable, i decided to use an old mobile phone to make a simple Home Security Alarm which is very useful and easy to make DIY gadget. This is one of a cool things that can be done with old cell phones. Any working phone with keypad that has speed dialing feature can be used to make this Security Alarm System.

Let's Begin..

Step 1: Watch the Video

There is no better tool than a detailed video tutorial to understand the procedure. However, it is also recommended to visit next steps for additional information and images.

Step 2: Required Materials

Almost all the parts can be found at home yet i will provide links to few of the parts that are available online.

Ebay.com

Neodymium Magnets - https://rover.ebay.com/rover/1/711-53200-19255-0/1...
Double sided tape - https://rover.ebay.com/rover/1/711-53200-19255-0/1...
Soldering Iron - https://rover.ebay.com/rover/1/711-53200-19255-0/1...
Hot glue gun - https://rover.ebay.com/rover/1/711-53200-19255-0/1...
Stationary Knife - https://rover.ebay.com/rover/1/711-53200-19255-0/1...

Amazon.com

Neodymium Magnets - https://amzn.to/2TQ6ZMX
Double sided tape - http://amzn.to/2npM6rb
Soldering Iron - http://amzn.to/2r3IX6g
Hot glue gun - https://amzn.to/2Sf7oad
Stationary Knife - http://amzn.to/2q879jK

Amazon.in

Neodymium Magnets - https://amzn.to/2Csqa7T
Double sided tape - http://amzn.to/2n9SjLI
Soldering Iron - http://amzn.to/2qC47qG
Hot glue gun - http://amzn.to/2rjNE9r
Stationary Knife - http://amzn.to/2q1kb6M

From Home and Local Store: Old Mobile phone, Enamel copper wire, plastic cloth clip, two conductive screws, cardboard and a plastic card.

Step 3: Prepare the Phone

Permanently turn Off the Keypad lock on the cell phone.
Turn On the speed dialing feature on the phone.
Assign a key to the speed dial and remember the key. (I used key no. 2)
Set the assigned key on speed dial to your mobile number.
After verifying all the settings, turn the device Off.

Step 4: Configure the Hardware

Disassemble the phone and separate the circuit board.
Clean any dust over the circuit and the keypad.
Carefully peel off the button sticker from the keypad.
Take two pieces of enameled copper wire.
Remove the enamel insulation from both the ends.
Solder the wires to both the terminals of a key to which a speed dial was assigned.
Remove the conductive plate from the button sticker of the corresponding key.
Paste the button sticker over the circuit board again.
Make sure that all the keys work well except the key on which the wires are soldered.

Note: It is advisable to watch the video to avoid any doubts and understand the procedure well.

Step 5: Prepare Contact Mechanism

Remove the enamel insulation from the other ends of the wires.
Take two conductive metal screws.
Tie the each wire to a metal screw as shown in the image above.
Drill a hole at the end of a plastic cloth clip.
Insert both the screws in the holes of the cloth clip, so that they can make good contact with each other.
Cut a small piece of cardboard and paste the cell phone over the cardboard.
Also, paste the cloth clip over the cardboard slightly above the cell phone as shown in the image.

Step 6: Make Magnetic Attachment

We now need to make a mechanism that can be pulled automatically, so as to activate the speed dialing feature of the phone.

Cut a small piece of non-conductive plastic card. (An expired Credit card can be used)
Heat the card from the middle and bend it at an angle of 90°.
The plastic will retain its shape when cooled down.
Using Hot glue, paste a strong neodymium magnet over the card.
Attach another magnet over the pasted magnet and insert it between the cloth clip.
Paste some double sided tape at the back of cardboard.
Apply some hot glue over the magnet and paste the system over the edge of a door as shown in the image above.
The other magnet will stick to the wooden edge and it will form a locking mechanism between the two magnets.

Step 7: Testing

Our Home Security Alarm is now ready.
Whenever you leave your house and someone opens the door, the card will be pulled out from the cloth clip due to the magnetic attraction and you will receive a call on your phone.
In this way, you will instantly know if someone has enter your home without your permission.
If you enter the house, all you need to do is cut the call that the security system will dial to your cell phone.

So Friends, this here concludes the instructable, if you like my project kindly support me by subscribing to my youtube channel GOODTECH - Creativity And Science.

Stay tuned and also follow me on Instructabes to receive regular updates. Kindly leave your valuable suggestions and feedback in the comments section below. You can also connect with me on through social media, Facebook, Twitter and Instagram.