The interest in speed controllers for R/C models is still just as great as ever, and we can confidently state that the Speed Controller Duet sets a new standard in this area. It is a universal system that can be used in all branches of R/C model building, including electrically powered aeroplanes, boats and cars. An equally important feature is that almost everything is programmable, thanks to an RS232 interface that allows the controller to be linked to a PC.The Speed Controller Duet is a modular system. Its intelligent heart is formed by the SpeedControl unit. This microcontroller-based circuit does not contain any power output stages. These are instead built as separate units that are controlled by the SpeedControl. This division of functions is actually quite logical. After all, processing the received pulses has little in common with driving electric motors with currents of several tens of ampères.