In our case, the switching module is the MT3608 IC which has a high switching frequency of 1.2MHz. It is a type of switch-mode power supply as it uses a switching device to regulate the voltage. info about Adjustable Step-Down Voltage Meter Power Supply Module. A boost converter(DC-DC step-up converter) is used to step up a lower voltage to a higher voltage level with quite a simple circuitry. The only dumb question is the one you don’t ask, Sorry I’m just wondering, will this circuit do exactly what my original schematic will do or do I need to change any wires (Might be a dumb question). I definitely plan on checking out Fritzing more to see if I like it better than CircuiTo.IO. That said, no it isn’t identical to your original circuit, but that circuit likely won’t work. The raw pin has a 5v regulator connected to it, so the input voltage needs to be something like 7V or so (to a max of 12V I think.) A single cell Lipo battery is 3.7 to 4.2V (discharged to fully charged) so doesn’t have enough voltage to support the regulator on the raw pin. That is why you need the boost regulator on the charger board. Connecting the +Vout pin from the boost supply to raw on the pro mini, and adjusting the boost to be 7V will work, and then the HC05 will connect to VCC on the pro mini (which provides regulated 5V from the regulator on the pro mini.) As will setting the boost voltage to 5V and applying it to the VCC pin and the VCC of the HC05 (which is what I did here.) Your original circuit is also lacking any charging supply connection, you would need to supply a power source to the two right side pins of the boost module to charge the battery.
