Components

Know your parts

Ten parts make the car think, move, listen and shout. Here is what each one is, what it is rated for, and where it goes.

The control board. It reads the letters arriving over Bluetooth and decides what the wheels and the buzzer do.

The power stage between the board and the wheels. The Arduino cannot drive four motors; the L298N can.

The radio link to your phone. It hands the Arduino one letter per button press, and nothing else.

The body. Four 1:48 gear motors under a clear deck, two on each motor-driver channel.

The horn and the tunes, on digital pin 2. It has to be a passive buzzer, not an active one.

The fuel. Two 3.7V cells in series give the 7.4V that the motors and the Arduino both run on.

Holds the two cells and wires them in series. Check it really is series — parallel looks identical.

Charges each cell to 4.2V and stops. The stopping is the point, and why a phone charger will not do.

Male-to-female ribbon for the modules, solid-core wire for the screw terminals.

A clear box for the boards on the top deck. Keeps wires out of the wheels without hiding anything.