In this project I hacked an Of-The-Shelf RC submarine (49Hz) to be remote controlled by Android Application! The whole project and each part of it can be used as a reference to endless variety of projects (Arduino - BT, Android - Arduino, electronics hacks, remotes...)
The main challenges were:
The project was fun and challenging - enjoy!
The (yet) UNHACKED RC submarine
The HACKED RC Submarine
I removed and dismantled the remote (As can be seen in the pictures) and searched for the location of the buttons, tried to figure out what is the working voltage the remote (6V), and how can I replace it.
The main thing that I wanted to gain is to be able to connect the Arduino board and the remote to the same power supply so If i need to ground a button in purpose to activate it, both (Arduino and remote) will have the same ground.
I found a variable power supply thrown in my junk box and set it to supply the 6V (I suspect that the current it gives is too low) - but it connected good and did the development role i needed.
I also found out that the when pressing on a key in the remote it grounds it, so I needed to imitate it to control the submarine.
IMPORTANT! the submarine doesn't "know" that it is controlled by something else then its original remote.