Planet Arduino

[Apachexmd] wanted to do something fun for his three-year-old son’s birthday party. Knowing how cool race cars are, he opted to build his own Hot Wheels drag race timer. He didn’t take the easy way out either. He put both his electronics and 3D printing skills to the test with this project.

The system has two main components. First, there’s the starting gate. The cars all have to leave the gate at the same time for a fair race, so [Apachexmd] needed a way to make this electronically controlled. His solution was to use a servo connected to a hinge. The hinge has four machine screws, one for each car. When the servo is rotated in one direction, the hinge pushes the screws out through holes in the track. This keeps the cars from moving on the downward slope. When the start button is pressed, the screws are pulled back and the cars are free to let gravity take over.

The second component is the finish line. Underneath the track are four laser diodes. These shine upwards through holes drilled into the track. Four phototransistors are mounted up above. These act as sensors to detect when the laser beam is broken by a car. It works similarly to a laser trip wire alarm system. The sensors are aimed downwards and covered in black tape to block out extra light noise.

Also above the track are eight 7-segment displays; two for each car. The system is able to keep track of the order in which the cars cross the finish line. When the race ends, it displays which place each car came in above the corresponding track. The system also keeps track of the winning car’s time in seconds and displays this on the display as well.

The system runs on an Arduino and is built almost exclusively out of custom designed 3D printed components. Since all of the components are designed to fit perfectly, the end result is a very slick race timer. Maybe next [Apachexmd] can add in a radar gun to clock top speed. Check out the video below to see it in action.

A few years ago Sven and Juho started working on the same type of project without knowing about each other and only by a coincidence their paths crossed. They wrote me about their cool story and the successful experiment of upgrading a diesel engine using Arduino Mega:

There’s a prettty large community out there in the car/motorsports hobbyist world that loves their vehicle but the engine is getting old, worn out and maybe even too bad to renovate. What people do is to take the engine from a newer car with a modern direct injected diesel engine, with all the cables, sensors and motor controller (the ECU) and adapt it to their beloved old car. This is exactly what is going on with the VW buses (called vanagons in the US) where the diesel engines from the beginning is a bit on the small side and 20 years later their performance is not much better than a garden tractor. A “new” electronically controlled engine is used to replace the old worn out engine, and with that follows better power, less pollution and way better fuel economy.

BUT, this takes time and is a complex project. You have to adapt the cablage, install the ECU (the motor controller) and must be sure that all the peripheral sensors sitting all around the engine is brought over to the new car and is working. You might also have to adapt the instrument cluster behind the steering wheel to make all the warning lights and gauges to work again.

The idea with the Arduino controller is to take the ENGINE ONLY and then let the Arduino manage the engine with the sensors that is on the engine itself. By doing this, the motor swap is reduced to a weekend project and everything in the bus is working as it was before. No instruments modification, no need for external valves and sensors, no adapted cablage. Just the Arduino.

You can find the whole documentations and the details of the project on Juho’s website.