Final Project: The Puzzle of a Works-Like Model

Today, my partner Christina and I worked on creating a mock-up of what we wanted our final project to work like. Using Legos, foam board, a breadboard and bulbs from the Physics Lab, we managed to created a miniature of the energy bike set up. All the bulbs we attached in series, so that as each switch was flipped, they would become a little dimmer as the resistance increased. Because we did not have access to a generator, we improvised a 9 volt battery. Our Lego bike and chain configuration represents the user and how the bike motion will provide power to the generator, which in turn will provide current to the circuit.

Works-Like Model Energy Bike

 Our model includes an (optional) outlet. If we have time before the due date, we have thought about adding an appliance option, so that the user could see how much power a basic piece of technology, like a hairdryer, requires to run.

Energy Bike Circuit Diagram (Iteration 3)

Our circuit puts the two types of bulb (incandescent and fluorescent) in series, but each series is then connected in parallel, such that all eight can be on at once without more effort than it takes to power one series.

Our Completed Circuit Based on Iteration 3

For this model, the switches were required to be on the breadboard, which is attached to the back of the foam-board. However, if we use switches in our final version, they will either have to be on the front where another user could manually activate them on on the handlebars of the bike so a single user could operate the entire display without dismounting. To avoid the user having to do anything, we could simply user a timer-program to turn on the lights at different points. This way, the user would only have to focus on pedaling and overcoming the steadily increasing resistance.

We ended up having to recreate our entire circuit from our original design (see previous post) because the parallel set up would not increase the resistance as more bulbs were added to the system. Fail fast and frequently...

Once the circuit was built, we had to test it to be sure it worked to our specifications.

To our great relief, the circuit worked perfectly. Each time a new bulb was added to the circuit via a switch, the previous bulb(s) became slightly dimmer. Though we can not directly experience it on this model, the increased resistance will be evident to the user on the cyclist. They will have to pedal harder in order to keep the bulbs (mostly, the incandescent ones) lit.

Stand-In with Functioning Gear Train

Overall, our model represents what we expect to happen during our final demonstration. Though we did not have access to a generator, our Lego stand-in's gear chain does work, and can visually simulate the task. As we built our model, and found we had trouble doing so, we realized just how difficult this project is going to be.

In the first place, we will need to calculate what kind of generator and bulbs we will want. All this will depend on the range of the user's pedaling ability. We do not want bulbs that cannot be powered by the generator, or worse, bulbs that burn out to easily. Safety is also a concern. The generator could overheat, or the bulbs could become very hot, or even the circuit board could reach dangerous temperatures. This project will require careful wiring and calculations prior to experimentation. However, while the bulbs can easily be tested until a usable combination is found, the generator is a one time shot. We cannot simply buy a bunch of generators or motors to test at random: that would consume our entire budget. To solve the issue of the varied/too little/ too much current, we may have to include an inverter on our list of supplies. Beyond the initial set-up and look, what our mock-up really demonstrates is just how tedious and detail-oriented our road to the final product is going to be.