Custom Car Horn

This custom car horn project has to be one of my all time favorites just because of the reactions I get from people when they hear it. The inspiration for this project came from hearing cars with a similar setup or a PA system. While a relatively straight forward project, I learned a lot from this project. 

For this project I needed a power source, PCB to run the system, dial selector, button, loud horn, and an amplifier. The PCB used was an Adafruit Audio FX Sound Board because it was a plug and play solution that did exactly what I needed. The power for the system was actually sourced from the fuse box where I used a Add-A-Circuit Fuse Tap. I needed to pick a circuit to tap that would only be powered on when the ignition switch was turned on. I ended up tapping into the 12V USB outlets as they met the requirements and was a non-essential circuit to the basic function of the vehicle. 

Once I had all the parts, it was time to wire up the system, program the board and give it a test. The programming of the board was made simple with the instructions online. Download the .wav files you wanted to play, plug the computer into the board, and then load the files. Based on how you name the files, you get different affects (loop, random, cycle). The selector has pins for each setting and I wired each pin to the corresponding trigger pin on the board. The button was wired to power and to the selector and worked like a charm.

I wanted the horn to look like it was stock and to hide all components. To do this, I did all the wiring behind and under the dash, even routing the wiring through the firewall grommet. Even the horn itself is hidden in the bumper and the amplifier mounted behind the lower dash panel (next to the OBD-II port). The selector and horn button were integrated adjacent to the steering wheel with holes drilled into the panel.