I want to introduce one of the minimalist way for stepping-down of 9V battery to 5V. We only need two component:
- 1x 9V battery clip (~$0.4)
- 1x AMS1117 1A or LM1117 5V 1A output voltage regulator (~$0.1)
AMS1117 voltage regulators are available in five fixed voltages; 1.8V, 2.5V, 2.85V, 3.3V, and 5V. Besides, it offers adjustable/fixed output and with on-chip current limiting and thermal shutdown. Common usage adds a few capacitors to both input and output where the transient response and stability is critical. But assuming to use this way for already protected device (like development boards etc.), in this work we don't need these capacitors.
Cut the plastic cover of the 9V battery clip and remove the cables from it by heating the solders. Then, place the AMS1117 near to positive head of the clip, as seen in picture. You should widen the distance between legs of AMS1117. Finally solder the legs and wires as seen in the picture.