The Blueson A1 is a powerful yet affordable 4in1 ESC but like all other 4in1 ESCs it comes with one drawback - wiring. When you are wiring a combat robot instead of using a flight controller, there's no easy interface for the standard 8-pin connector found on many of these ESCs. Well, at least not until now!Introducing the BETA V0.3 Blueson A1 Backpack PCB. This board features a 36V tolerant linear voltage regulator capable of powering a standard ELRS receiver with up to 6S LiPo input (or 8S with added cooling - this may be addressed in future versions). This backpack PCB handles several important functions. Provides a breakout of the 8-pin to helpful labeled pads Has an onboard power LED and voltage regulator to convert battery voltage to 5V for a standard RC receiver Has a 6 pad breakout of the ground, 5V and motor signals to a secondary PCB The secondary PCB has a set of 12 holes perfectly aligned for an ER4 (or R84) receiver to slot and solder in place, allowing for a compact right-angle sandwich board construction Matching 20x20mm M3 mounting holes allow for the whole board to act as a 'backpack' when combined with a Blueson A1 ESC and a suitable 3D printed spacer (not included). V0.3 CAD download available here. Note this is a rough approximation CAD for the ER4 receiver, spacer, and total board arrangement. The A1 may be flipped to either orientation. eCAD view: top and bottom Full schematic: