septillion:
Just looking at the site you listed before I would go for:
LM2596S LM2596 DC-DC Buck Converter Adjustable Power Module | Lazada PHIf you're planning to use the servo heavily I would add a small heat sink but if you don't tend to let the servo stall/move heavy stuff it's fine.
can i connect the HC-SR04 also in this with the servo motor?