Simple Brake Light for FS Vehicle

Brake light PCB is a simple board containing 24 red LED’s, power section, and a low-side MOSFET switch in order to control it. It simply just lights up when a car is braking. This PCB is used in PM07, second fully electric car from PUT Motorsport - Formula Student Team. Brake light is obligatory component to participate in FS events, it must also meet the regulations such as minimum illuminated surface of 15 cm2 with even luminous intensity, and maximum spacing of diodes being 20mm. The light must be red, and be clearly visible in high sunlight. The circuit operation is fairly simple, when the MOSFET gets signal from brakes (SIG_BRAKE, 5V from AQ card) it closes the circuit to ground lighting up all LED’s. Power section contains 18V voltage regulator in order to get a stable voltage across the circuit, a fuse, overvoltage protection and noise filtering capacitors. 

Project supported by: https://jlcpcb.com/HAR

The LED’s we choose are REFOND RF-RURA30TS-CE, because of high viewing angle (120°), low profile (it was important for us to keep the PCB as low and light as possible), and high luminosity (542...1192mcd), the parameters of used diodes are shown below on attached picture. Beside of that you will need a:

• single BSS138 N-Mosfet
• 10kOhm 1206 SMD resistor
• 100Ohm 1206 SMD resistors
• 4x 470Ohm 1206 SMD resistors
• 330 Ohm 1206 SMD resistor
• MC78M05 TO252 voltage regulator
• 2x 100uF 1206 ceramic capacitors
• signle Schottky diod
• SMD fuse

Whole project is made using KiCad 5, open-source PCB design software.

To get the PCB manufactured, you have to upload the Gerber files in a .zip, or .rar file. If you don’t know how to generate proper gerber files in KiCad 5? JLCPCB provided a proper tutorial:

https://support.jlcpcb.com/article/149-how-to-generate-gerber-and-drill-files-in-kicad

After uploading your files it is time to adjust your PCB settings, as you can see you have many options to choose for example even the colour of your board(we have chosen red).Everything here is clearly marked, but if you are still not sure about something you can click on question marks to learn more. To make sure you will be happy how your PCB’s will come up, when you are done with your settings, you can click Gerber viewer to see the glimpse of end result..

Last checks done, it is time to order. In case of this project, there is 2$ for 5, 2-layers PCB and it will take only 1-2 days to build. To place the order, click on the “SAVE TO CART” button.