The alternator through the rotational movement of the engine is the main supplier of electricity in a car as it converts the kinetic energy of rotation of the combustion engine into electrical energy; the electrical system is the central part, because their functions ranging from constantly charge the battery to provide power to the car while it is running. Knowing each of the parts of the alternator is essential when diagnosing faults, among them we can see four main: the rotor, stator, the regulator circuit and the rectifier circuit. This thesis is focused on the design and construction of a test bed for alternators with which we will be able to check the correct operation of these elements under conditions similar to those obtained in a vehicle, through the ease of measurement values such as voltage and amperage, in different ranges of RPM, facilitating diagnostic work maintenance and / or repair of these items to have more space for the check besides having such a useful tool as it is a test with these characteristics.