This page explains how to use the Parallel Port of your PC to control a model racing car.
The circuit below was designed by Malcolm Lear, our hardware development guy. It's pretty simple - a resistor and transistor for each data line. The Parallel Port gives you eight data lines, and the circuit below fully utilises these allowing the control of two cars. Each car needs four data lines, one for each of left, right, forwards, backwards.
The full schematic is here - this gives details of all the components used.
Below are some photographs showing various views of the board.
The picture above shows the board connected to an RC control unit. This requires some care. The RC unit should be taken apart carefully, then the connections need to be made between the ribbon cable and the RC ground, and the switches for left, right, forwards and backwards. The circuitry is quite intricate, so you need someone who's handy with a soldering iron to do this.