There were really 3 parts to our prototype: the circuit, the generator, and the mechanism which converted the motion of the door into motion of gears (hereby referred to as the door mechanism).

Grace primarily worked on the circuit and generator 2.0 because she was distance learning for the majority of the winter. Adam and Jack worked primarily on the door mechanism because they had access to vex parts in school. All members worked to combine the parts in the spring.

The generator addressed the design specification of generating electricity. Consistency and reliability were addressed by the circuit and the door mechanism. Safety and conformation with regulations were addressed by all parts of the prototype.

Refinements during this process:

We had to adjust the angle at which the gears were placed and turned due to how our generator was constructed. Additionally, another gear was added to keep the rail from slipping.

Materials:

We used vex parts which were ideal for our purposes because they could be easily configured and were relatively small.

The basic design idea was that there would be a rail gear that would turn a rotational gear which would turn the generator's axle. We started by making the housing in which the rail gear would sit. Then we put the lever that would attach to the wall and attached the gear to the top. Below is an image and a video showing this design.

Below is a video of it successfully translating the motion of a door into rotational motion.

We then tried to see if we could really rotate a small generator. For this we used a hand crank flashlight. Below is a video of the test. This test was successful and thus we considered the door mechanism completed.

An issue we experienced with this prototype was that the rail and the gear did not always remain in contact with each other. To solve this, we first tried using screws to keep the rail in line. However, this caused too much friction. We then added another gear to increase the potential surface area. This successfully resolved the issue.

Refinements during this process:

We had to troubleshoot many different issues throughout this process. We had to adjust materials, wiring, and the number of coils and magnets for our final design consistently generate enough electricity.

Materials:

For the test prototypes (versions 1.0-2.0) we used cardboard and K'Nex parts. These were ideal materials because they were readily available and easy to adjust. For all the versions, we used rare-earth magnets which are very strong. However, we would have liked to have had a larger quantity and stronger (larger) magnets but were limited by budget constraints. For the final version (version 2.1), we 3D printed the magnet plates and used wood for the coils of wire. This was ideal because the magnet plate fit perfectly with the VEX axle and the wood allowed us to get the magnets closer to the coils. Additionally both materials were more stable than the cardboard used in our initial prototypes.

Version 1.0

The first version of our generator was made of thick copper wire, cardboard, and K'Nex pieces. This version topped out around 50 mV due to several things: the lack of magnet wire, few coils, instability and friction, and incorrect wire connections. Although the general design - stationary coils and spinning magnets - did not change between the generator versions, several revisions were needed to improve the voltage output of the generator.

Version 1.1

Due to the low voltage output of our first generator, we considered using the generator within a hand crank flashlight. The coating of the magnet wire needed to be stripped in order to get a voltage reading. The small diameter of the wire made it difficult to strip without breaking the wire. The magnet was very weak and the way that it rotated did not expose the coil to a large magnetic field. Although this ended up being unsuccessful, the experimentation with the generator within the flashlight led to discoveries that would allow us to create a functioning generator.

Version 2.0

There were several tests that went into creating version 2.0. First was a test to determine how more coils would actually increase the amount of electricity. We observed that the coils only increased the voltage if there were half* as many coils as there were magnets. However, this result did not align with Faraday's Law as we understood it. Thus we hypothesised that there was another issue. The breakthrough was using Lenz's Law, explained in element E to figure out that we needed to alternately wire the coils. We also tested how different numbers of magnets and coils impacted voltage output. We ended up using a total of 16 magnets (8 on the top and 8 on the bottom) and 8 coils.

*The number of magnets compared to the number of coils is equivalent to the number of times the magnetic field changes during one rotation. We technically used 16 magnets but the magnetic field only changed 8 times in one rotation because the magnets are aligned on top of each other to act as a bar magnet between the two plates.

Below is the generator I used to test different set ups to find the optimum placement of magnets and coils. The coils used for the tests were 4 coils of 150 turns each.

The largest problem we encountered with the first generator was the lack of magnet wire. Because of the lack of coating on the wire wire, the charge would "jump" several turns and the generator would act as if each coil fewer turns than it actually did. Thus we had to purchase magnet wire. We also got thinner wire so we could have more turns per coil. In the final version, there were about 300 turns for each coil and a total of 8 coils.

The rest of the revisions were focused on exposing each coil of wire to the most magnetic field possible. To do this, we used 2 plates of magnets - one on top of the coil plate and one under the coil plate. We were limited in the strength and number of magnets due to budget constraints.

We also were able to use steel nuts, a ferromagnetic material, to increase the magnetic field through the center of the coils. This increased the voltage produced by about .1V (around 10%).

Friction was reduced by stabilizing the axle using a wheel hot-glued to the cardboard and not allowing the cardboard to touch the plastic as we found the cardboard caused significantly more friction than the plastic wheel.

Below are images and videos of the final design.

Version 2.1

Generator 2.1 used the same general design as generator 2.0 but was made out a materials that made it more stable.

• The magnet plates were 3D printed.

• VEX gears were used to stabilize the plates.

• The coils were placed on wooden plate.

• The arm bar and casing was made of VEX parts.

Refinements during this process:

Our final circuit used capacitors wired in parallel while charging, then series while discharging. This was different from the planned circuit that had the capacitors wired in parallel for both charging and discharging.

Materials:

We were able to use the most ideal materials possible. Of course a diode with a 0V forward voltage drop would have been better, but those do not exist so schottky diodes with .2V drop were good enough.

The first thing we had to design was a rectifier. This would turn the alternating current produced by the generator into useable direct current. To do this, we used schottky diodes to minimize voltage loss (.2V drop each).

The next thing we needed to address was the differing voltages depending on how the door is opened. Thus we designed a circuit that was capable of converting low and high voltages into stored energy by using an SPDT relay. When there is a low voltage, the current goes directly into the capacitor or battery. When there is high voltage, the current goes to a voltage regulator first.

Lastly was the issue of energy storage. For the purposes of the test circuit, we used capacitors so we could quickly see the voltage climbing though it would be quite easy to replace the capacitor with a rechargeable battery. The real test circuit did not actually use capacitors but rather LEDs to indicate which part of the circuit (high or low voltage) was being activated.

Below are images and videos of both the TinkerCAD circuit and the actual circuit working.

Refinements during this process:

Many minor refinements were made during this process. The most notable refinements that have not been discussed yet include replacing the VEX bars that hold the generator to the door mechanism with wood and stabilizing the axles.

Materials:

We used VEX parts for our prototype because they were easily adjustable. However, the VEX parts did not fit perfectly, which made it difficult for the prototype to work efficiently and consistently.

The first attempt to combine the parts was the flashlight model. This model ensured that the door mechanism could be used to turn the gear of a generator.

Once generator 2.1 was created, it was mounted in such a way that it could be turned via a gear and sprocket system. Some adjustments that had to be made in this step of prototype creation included experimenting with the gear ratios to ensure the generator could be turned and adjusting the gear heights to ensure the chain was parallel to the rotation of the sprockets.

After the testing of generator 2.1's voltage, the circuit was finalized, connected to the generator, and attached to the door.

Further adjustments were made to improve the prototype's efficiency including stabilizing the axles by adding an axle holder to the coil plate, replacing the VEX bars that held the generator to the door mechanism with wooden bars, and securing the generator to the bars with tape.