The availability of cheap but powerful sensors and signal processing hardware allows the solution of problems, which previously could only be solved at high costs and efforts. In this paper we describe an approach to locate an acoustic sound source by three low cost microphones and operational amplifiers in combination with a simple microcontroller using its embedded analog/digital converters. There are several applications, e.g. the detection of the direction and distance of a police car by the sound of its siren or the location of a speaking person by an assistance robot in a household. The complete real-time analog/digital signal processing chain using cheap hardware is in the focus of this approach. By deriving an approximate solution for the location equations, the approach becomes suitable for low-cost microcontrollers.