Electrical Engineering

The engines main electrical system enables the raspberry pi computer to communicate with the rest of the engine components. The main components including the oil pump, fuel pump, spark plug, and NOx sensor power are all switched on and off using relays. These relays are switched using a low power auxiliary system needed to protect the rpi from damage during operation. 

From the battery, 12V DC travels through a thermal circuit breaker and on to the main fuse panel. From there 12V is distributed to the relay panel, main computer, and the relay switching circuit. All engine components are grounded through the engine frame, components located on the control board are grounded through the main fuse panel. 

The low power relay switching circuit uses a system of transistors and diodes to ensure proper current flow. When triggered the rpi produces a 3.3V signal from one of its GPIO pins. This voltage trips the transistor, completing the switching circuit by connecting the ground. With the switching circuit complete it will trip the relay with will provide the necessary subsystem with 12V.