Version 1

10/2023 – 11/2023

INTRO

This is the BSPD (Brake system plausibility device) which is required by FSAE rules. This board detects when brake pressure is high while there is also high current flowing from the battery, and shuts the car off. This is to protect the driver from any malfunctions and is lifesaving in an emergency. This board is extremely important and must be dead reliable in order for it to prove useful to the safety of this vehicle.

V64 BSPD BOARD

This is the BSPD from last year. One of the notable issues with this board pertains to the multitude of wires and components that were incorporated into it, which could potentially experience connectivity issues if mishandled. The design of this board has evolved to its third generation, with numerous significant enhancements along the way. The schematic has been substantially simplified, focusing on its fundamental components to guarantee both reliability and long-lasting performance.

SCHEMATIC

This schematic was designed after the V64 board. Some of the most significant changes are the implementation of a better relay and a more simplified input to the comparator which detects faults in the system.

ORDERED PCB’S

I ordered the PCB’s for this board on my own so I could get ahead on testing for this circuit. Unfortunately, because of a latching circuit that needed to be added and a different choice in connector, this board will just be desk art. The new board is coming soon and will have all final changes needed.

Version 2

11/2023 – 1/2024

CHANGES

In this version of the board, I opted to put all the components on one side for easier viewing, troubleshooting, and assembly. I also added the needed latching circuit by using a triode that latches once is has received a high signal representing a fault.

PROBLEMS

After assembling this board, it didn’t work, at all. The comparator (U1) was not comparing the analog voltages correctly, and the OR gate (U2) was constantly outputting a high signal. The comparator (U3) also was not working as intended. The only parts of the circuit that actually worked were the 12V and 5V power sections. After a few days of testing, I could not figure out why the IC’s weren’t working, I tried bodging the board and replacing IC’s but to no avail. My only conclusion was that the IC’s were getting fried when they were being soldered, its the only reason that made any sense since the IC’s were exactly what I needed on their data sheets. So in all frustration I made a test board.

TEST BOARD

I spend an afternoon making this board to test if my circuit was actually garbage or if I was simply having problems with my components. After picking equivalent parts from my school’s electronics part room, I made this board and started to test the functionality of the circuit, it worked flawlessly, the circuit was super accurate and did everything that I needed it to do. As much as I love to make a small compact board with tiny SMD components, I had deadlines to meet and needed to present a circuit that worked 100% of the time. So I quickly redesigned my PCB and made it with components that we had in abundance at the school, that way I can avoid placing another Digi key order and potentially wasting more money on parts that may not work again, and this way I know that the circuit will 100% work, all I had to do was copy my perf board. To this day I am still confused why those SMD parts didn’t work, it had to be because of overheating when soldering but it doesn’t make sense.

Version 3

2/2023 – 3/2024

CHANGES

This version of the BSPD uses through hole components since they’re readily available in my schools part room and since I know they worked from the test board. The board also uses a different connector that is stronger and is also readily available online.

V3.0 and V3.1

In version 3.0 (the green board), everything worked as expected, except the fact that a MOSFET had its source and drain mixed up, hence the little green wire on it fixing that issue. In version 3.1, this board was meant to fix that mix-up, but the bottom polygon pour got mapped to the wrong net, and didn’t connect 5v to any of the components. Version 3.2 will fix all these silly issues and will hopefully result in the final board.

V3.2

This is the final version of the BSPD, it works flawlessly and has had rigorous testing done on it. It is now racing in the 2024 FSAE race in Michigan.