Electronic voltage regulator, mounted away from the alternator in the engine compartment Electronic voltage regulator, mounted on the back or inside the alternator . The contact point voltage regulator uses a coil, set of points, and resistors that limits system voltage. The electronic or solid-state regulators have replaced this older type. In fixed voltage regulators the reference pin is tied to ground, whereas in variable regulators the reference pin is connected to the centre point of a fixed or variable voltage divider fed by the regulator's output. A variable voltage divider such as a potentiometer allows the user to adjust the regulated voltage.