Hi guys,

Today I’ll show you how to build a remote trigger with your old cell phone. You don’t need much stuff and the trigger will be useful for all kind of stuff that I’ll show later.

Requirements:

• Old cell phone, must support silent mode with vibration
• Old SIM card (working)
• 2 wires
• Screwdriver
• Diagonal pliers
• Small block of wood/rubber/plastic
• second, working cell phone to trigger the other one

WARNING: YOU ARE DOING THIS EXPERIMENT ON YOUR ON RISK! I WON’T BE RESPONSIBLE FOR ANY DAMAGE CAUSED TO YOUR PROPERTY!

Here I’m using my old Nokia 3200, but you can apply this tutorial to any other cell phone model.

First of all, remove the casing of your phone. That should be quite easy. Next take out the battery and SIM card. Now, and that may depend on your phone model (my one has torx) use a screwdriver to disassemble the internal parts of your phone. Usually they have 6 screws of the Torx 6 format.

My Nokia 3200 consists of 2 parts, one curcuit board holds the keyboard and screen, the other one the computing stuff (memory, processor, SIM card, …). It looks like this:

When you look into the casing, you should see a small electric motor with a weight at its axis:

When this motor rotates, the weight, hanging only on one side of the axis, creates a momentum force perpendicular to its current line from center of gravity to mid of axis, pulling the phone in the direction of the phone. Since it’s rotating, the direction of this force changes all the time, and the phone is pulled in alternating directions, thus creating a vibration.

But we don’t want the phone to vibrate, it should trigger something. So we remove the motor (you can simply pull it out), but use its power supply.

As you can see in the image above, the motor has 2 metallic contacts, used to transfer the power. We need to connect them to our trigger, so when somebody calls the phone and it would usually vibrate, it now gives a signal to whatever you want to trigger.

You can either solder 2 wires directly to the phone’s board’s contact counterparts, or do it the way I did it: By creating an block with 2 contacts similar to the motor we removed.

Here you can see the phone’s contacts for the vibration motor:

You will need a hole in the phone’s back so that the wires can come out, so just drill one where the weight on the axis has been:

Then take a wooden block the size of the motor and placed it where the motor previously has been:

Now punch two holes into the block with a needle at the same distance as the contacts, so you can plug in the wires later:

Now take two equally-long wires, remove around 5-7mm of the isolation from one end, and twist them around each other:

After that, bend the unisolated ends around a screwdriver and make a knot in the cord, so it won’t drop out of the hole you drilled:

Now insert the blank ends of the wires into the holes in the wooden block, and pull the other end through the drilled hole. It should look something like this:

Hold the phone’s computing board over your construction and check whether the blank ends of the wires touch the contacts on the board, so that the power will be transfered.
Then reassemble the whole phone excluding the vibration motor, screw in the screws, put in SIM card and battery, and give it a try

Now start the phone, enter PIN, switch to silent mode and call it from another phone. If you connect a voltmeter to the wires coming out from the body, you should be able to measure the current! If not, check the contacts inside the phone.

Here it’s working fine!

I will continue this post tomorrow, it’s after midnight already and I should get some sleep… I hope you enjoyed reading this!