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 integrated circuits of the series 79xx, where the xx can vary from 05 to 15 indicating, voltages from 5 to 15 V.
In Figure 1 we have the complete circuit of a negative voltage source, using a 79xx Series IC.
It should be noted that the arrangement of the terminals in the ICs 79xx is different from the ICs 78xx. The printed circuit board for mounting this source is shown in figure 2.
The integrated circuit must be provided with an appropriate heat radiator and the output decoupling capacitor may have values different from that indicated, according to the IC manufacturer.
The transformer must have a secondary winding with a voltage of at least 2 volts more than the desired voltage at the source output, ie the voltage of the regulator used.
Material list
CI-1 - 79xx - negative voltage regulator integrated circuit
D1, D2 - 1N4002 - rectifier diodes
T1 - Transformer - see text
C1 - 1000 uF - electrolytic capacitor
C2 - 10 uF x 16 V - electrolytic capacitor
F1 - 500 mA - fuse
Several:
Printed circuit board, heat radiator for integrated circuit, socket for fuse, power cable, wires, solder, etc.
