AT25 Journal
This journal will document my findings and progress throughout the project.
Day 1 (June 19th)
Time Spent: 3
Total Time on Project: 3
Day 1 involved researching and selecting the necessary components. I plan to order most of the parts from GreatHobbies, a Canadian hobby store.
Initially, I selected the battery based on my preferred voltage of 7.4V due to the availability of batteries and motors, and it being at an ideal performance range. For the capacity, I opted for 5000mAh to achieve a decent runtime while remaining cost-effective.
Next, I chose the motor, which required thorough research and consideration. After evaluating the options, I decideed that using a single motor for a RWD setup would offer better cost-effectiveness and performance than 2 motor AWD. The selected motor is a 1406-2280KV, 4-pole sensored model, which can be found in the Bill of Materials (BOM).
Lastly, I selected the tires. Although I originally wanted RC slick tires, the best available option was vintage racing tires. I chose a 26mm width for the front tires and a wider 31mm for the rear.
The BOM can be found at the following link: AT25 BOM
Day 2 (June 20th)
Time Spent: 2
Total Time on Project: 5
Today, I began laying out the general design of the car. I began by learning how the aerodynamic elements work and the different elements used. Through this, I got refreshed on Bernoulli's and got a surface level understanding on how the important elements work.
Knowing this, I made a rough sketch on paper as a guideline on how I will design the car. This rough work can be found below.
Finally, I made and found the 3D models for the components I will be using. My plan is to design the aero then determine the packaging for everything else, a similar process used in F1 and other design teams.
Note: I changed the battery to a different, similar spec'd one due to a proprietary connector.
Day 3 (June 21st)
Time Spent: 5
Total Time on Project: 10
In Day 3, I began work on the brushless control board. The IC pre-driver I selected was the DRV8323S due to its 1 PWM mode (no extra code required), my previous experience with it, and its availability.
I preferably would run the DRV8320S but it is out of stock so I had to compromise. This IC would be better as it doesn't include the amplifiers which are not required due to the sensored motors not needing to know the current flowing through the coils.
Afterwards, I chose the CSD87333Q3D FETs as it is TI (I love Texas Instruments), it integrates both the high and low MOSFETs, supports up to 15A (the limit I'm designing for), and the high efficiency while being cheap and available.
Drawing the schematic mainly involved following the diagrams provided by TI. It was very straightforward; however, the PCB layout will not.
The final schematic for the board is this:
