In the same way that we can regulate the voltage in the positive branch of the circuit, we can have the negative regulation. For this purpose, we can count on the 79xx series integrated circuits, where the xx can vary from 05 to 15 indicating, voltages from 5 to 15 V. In the figure we have the complete circuit of a negative voltage source, using a series IC 79xx. It should be noted that the terminal arrangement on ICs 79xx is different from ICs 78xx. The integrated circuit must be equipped with an appropriate heat radiator and the output decoupling capacitor may have different values than indicated, according to the manufacturer of the CI. The transformer must have a secondary winding with a voltage of at least 2 V more than the voltage desired at the source output, that is, the voltage of the used regulator.
