The PCB, just the PCB and nothing but the PCB.
The PCB can accommodate 2 types of DC-DC step down buck converter (not included).
Remember to set the output voltage before connecting to the circuit. This is a very common module.
Fixed 9V output
This module is available with different output voltages (3v,5v,9v,12v). Double check you have the 9V version.
I didn’t intend to sell these, the Bluetooth modules I use are not the cheapest, but since I have been asked a few times I added them to the price list.
1 x 9V fixed output DC-DC step down convertor
1 x HC-06 Bluetooth module with separate pins.
The DC-DC step down converter has a fixed 9v output so there is no setup required. Just make sure you get it the right way around. Follow the arrow on the back
The HC-06 Bluetooth modules are the official (and original) modules from HC/Wavesen. These are more expensive than other similar modules but the HC modules are reliable and well supported and as a bonus they have a nice shinny blue LED and everybody likes shinny blue LEDs!
Although I recommend the HC01 modules you do not need to use them. Most HC-06 modules will work with the dropController.