|Abstract||In electrical power systems, dynamic stability problems may be solved through the application of power system stabilizers (PSS), which improve the performance of the main automatic voltage regulators (AVR's) of the synchronous generators (DeMello, Concordia), (Anderson, Fouad). This paper offers a simple and practical approach to design such power system stabilizers. A prototype PSS has been designed, built and tested in laboratory for a model synchronous generator. The circuits used in monitoring speed changes of the generator, their manipulation until they are mixed up with the input signals to the AVR are detailed. These circuits are composed of a sequence of stages for filtering and amplification of the monitored signals in addition to lead-lag compensation networks. The system has been put together and tested for different system disturbances. Three system indices; the power angle, speed, and terminal voltage are recorded at different operating conditions. These results show the effective damping effect of the PSS on variations in power angle, speed, and other system dynamics. The system has been tested for both small and large changes in operating condition.