I've started a little project for my 6 year old son, I'm going to attempt to make from scratch a small remote control car with a webcam on it. To control the car I'll need to write an Android application. The Android application will talk to a little computer called a Raspberry Pi (which will live on the car), it will display the output of the onboard webcam on the Android device and also recieve control instructions from the Android. A Raspberry Pi (also called RPi) is a credit controlled sized compuer that you can buy for under £30. It has input and output ports which you can use to control and monitor stuff. So the idea is that this little computer will be built into the remote control car, it will wirelessly communicate with the Android device, recieve control instructions and stream the webcam data. For the remote control car I've decided to go for tank control style steering, so I've ordered four high torque motors. These will work in pairs, so left side motors work together, right side motors work together. The motors require a 12v supply, so I'll need a "h bridge" motor controller board to link the 3.3v low amp control signals from the RPi to control the motors. A H-bridge is a circuit which enables a voltage to be applied across a load in either direction. I could buy a H bridge chip and make my own H bridge controller circuit but it's easier to just buy a ready made H Bridge motor controller cricuit board. So I've chosen this dual H bridge controller (dual as I want to control left and right motors). To allow speed control of the motors I'll need to implement some Pulse Width Modulation (PWM) from the RPi. I need to have think about how I will implement this but basically I think I'll need to write some software to generate pulses on the RPi of varying length to control the speed of the motors. I will also need to install a 12v (rechargeable) power source on the car and install a 5v voltage regulator to run the RPi. That's the hardware side, on the software side I'll need to write an Android application to display the video stream and also send control commands, on the RPi I will need to find some software to send the video stream and write some stuff to process the control commands coming from the Android device. I'm gathering hardward stuff together at the moment, I'll keep you posted as I make progress .. probably slow progress.