In my essay I present the design and construction of a DC/DC converter prototype, which is suitable to control various types of lightsources, and can be manufactured in series in the future. I review over the most commonly used, non-isolated converter topologies, and selecting one of these. I present each steps of the hardware designing (except of the printed circuit board), and finally make measurements to demonstrate the correct operation and the technical parameters. In the design phase I focused on the practical experiences. Before the construction phase, I have investigated the operation of the main parts with numerical calculation methods in addition to circuit simulation. The built and tested converter can handle 30A of output current at 16.5V input voltage in voltage source mode, and able to deliver 25A in current mode. The circuit gives a few comfort functions as the control (~ brightness) setpoint can be specified via external analog signal source, the operation can be enabled or disabled from external digital inputs, and the control method is also selectable. All of the digital control and safe-monitoring functions in the circuit are realized by the software in a dsPIC33FJ12MC202 type of microcontroller. The first prototype version in the tests surprisingly reached almost 94% efficiency, despite of the fact, that several parameters and optimizing the loss factor are even possible. At the end of the work I marked some development possibilities.