Water erosion is a natural phenomenon of great importance in the global scenario with regard to the conservation and sustainable exploitation of soil and water, and the use of rainfall simulators has generated numerous relevant information for the understanding of this topic. The improvement of these equipments aiming at the application of rains with variation of precipitation intensity and the development of an electronic runoff collector are crucial steps in the study of erosive processes. The thesis is presented in three chapters in order to approach the entire procedure adopted in the development and evaluation of the devices associated with the InfiAsper rainfall simulator. The objective of the first chapter was to develop a control panel capable of varying the rotation of the shutter disc, making it possible to obtain customized rainfall patterns in the rainfall simulator. The installation of electronic components in the InfiAsper control panel allowed the variation of the shutter rotation during its operation according to previous programming, allowing the simulation of rains with different precipitation patterns. Events with peak of precipitation intensity (PI) of 110 mm h^-1 and duration of 40 min were adequately simulated by the equipment, with uniformity above 75%. It is possible to simulate other patterns, with different PI and duration, by changing the settings on the device panel. The second chapter aimed to evaluate the prototype of the new control panel in the field, surface runoff and soil loss from advanced, intermediate, delayed, inverted intermediate and constant precipitation patterns in an Argisol. The panel was programmed to simulate rainfall of 40 min duration and a total depth of 30 mm in a terrain with a slope of 9%, graded in the direction of the contour and in an exposed soil condition. Operating with the new control panel, InfiAsper operated satisfactorily, allowing to vary the precipitation intensity, according to the characteristics of the rains expected in natural events. Intermediate and late rainfall patterns produced greater soil and water losses than the advanced pattern. The intermediate inverted and constant rainfall patterns did not produce significant losses for the application of an average water depth of 30 mm. The third chapter presents the development and field evaluation of a data collector for rainfall simulators, capable of quantifying runoff volume and automatically estimating the rate of soil loss. Using a microcontroller (Arduino Mega® 2560), sensors with capacitive, ultrasonic and pressure principles were tested to compute runoff volume, and a turbidimeter to compute soil loss rates. Sensors were selected for calibration and data uncertainty. The automatic runoff collector equipped with the PSI.420 pressure transducer and the ST100 turbidity sensor proved to be effective in obtaining and storing data on runoff volume and soil loss obtained during a simulated rain test in the field.