Frequently, when riding my bike I forget to turn my bike lights on or off. This has led to me riding in unsafe conditions, being hassled by police and killing the batteries on my bike lights. I also noticed that my friends and acquaintances have had the same issues. So my team decided to solve this by creating an economically feasible automatic bike light. We also collected market data so we had a clear idea about what was necessary for our project. You can view our DATA at the following google sheet. google sheet
What it does
We built a circuit that attaches easily to any wheeled vehicle. It uses a conductive plate and a extrusion of solder as a switch to complete the circuit and turn on the lights when the spokes cause the switch to close. We also designed and 3D printed a case to organize and house the circuit and battery, along with paying as best we could to aesthetics. The final constraint of our project is that it will be economically friendly to reproduce.
How we built it
We first decided on the constraints of the circuit then designed and built several variations before finding the one that best fit with our idea. We then designed the case around that circuit, and implemented it on the unicycle. Here's a diagram of our circuit as well!
Challenges we ran into
The first challenge was designing a circuit that allowed for long battery life and didn't waste battery life when the light was off. This meant we could not use the popular 555 timer IC as it has a high supply current. Our original circuit : We had some issues with this circuit which were solved when we removed the transistor and put the trigger on the same node as the RC timer portion and the output portion. We also noticed that the vibration trigger we bought from Adafruit only was triggered by horizontal not vertical movement so when soldering wires to the vibration trigger we accidentally destroyed it. So we decided to switch to a simple reed switch circuit.
However after we attempted to add a taillight, too high of a current was passing through the reed switch and we had to switch to a mechanical switch. It was a great critical thinking exercise coming up with a replacement switch with our limited materials. The solution we chose was winding a piece of solder so it became less flimsy then positioning it on the unicycle so the spokes hit it and caused it to make contact with a conductive metal plate, a spring between the metal plate and solder prevent them from making contact when the unicycle is not in motion.
Designing the case also had several challenges including the thickness of the case and how to attach it to the vehicle.
Accomplishments that we're proud of
We are proud of out circuit that satisfies our constraints, how we handled our challenges, and how much we have learned. The 3D parts we designed and printed came out very high quality and fit our project perfectly. Our teamwork and time management really shown through on the Illumicycle.
What we learned
One of our teammates learned digital image manipulation, and another gained serious soldering experience and circuitry. We also gained significant practice in debugging circuits. Be super careful and pray to the electronics gods when soldering. Always be careful with your power distribution and make sure your circuit is capable of powering everything on it. Reed switches can fail when too high of a current is being passed through them, they typically fail in the closed position, we learned this when ours failed. Our organizational skills improved along with working within the constraints of a human operated vehicle, and ensuring the device did not interfere with vehicle operation.
What's next for Illumicycle
We plan on ideally perfecting the Reed Switch version of Illumicycle and then improving the aesthetic before trying it out on the market.
Illumicycle: coming to the Cedar Rapids bicycle market this summer!
We chose Cedar Rapids because of the location and the prevalent bike culture there.