This post is all about the Science 9 Honors/ ADL10 electrical house project. For this project, groups of two had to create cardboard houses, and wire them with working circuits to light up the rooms. Tae and I decided to make a castle, with all the necessary circuits, including a working automatic door!

This is how that process went:

Define, Dream, Design, Debrief

Define: 

        For our project, Tae and I have chosen to make an old castle out of cardboard and create torches on the walls using light bulbs. For our circuit of choice, we have decided that we are going to be using a small electric motor to create an automated draw bridge. Originally, we were just going to use the cardboard we had on hand and attach string to it, but we soon realized that this solution would be flimsy and fall apart. We realized that a cardboard door would also not be able to withstand extensive use as the cardboard would become bent, and the course of its  opening/closing would change overtime, leading it too not close properly. This meant that we needed a door that was going to last being opened many times, and not wear out like a cardboard one. 

Dream: 

        One possible solution we had thought of was mentioned in the paragraph above. This was to attach a string to the front of our drawbridge to our motor, but we tested this, and we saw that this would be a flimsy design. The cardboard hinge would lead to the door constantly bending in different directions. Another issue with this was that the motor would be constantly wound in string which would cause knots and burn out the motor. Our main idea was to attach a 3d printed hinge and door and have gears going to the door to open it. 

        What we wanted to make was a door that fit in with our castle theme, but also was effective as if someone living in this miniscule house would be able to use it. The idea of a drawn bridge obviously came first, but as mentioned later, this was far from possible for the time, space, and resources provided. We thought of a two-door design that would open using two motors, and even though the load of the door would be more evenly distributed, the friction and complication of the system would overwhelm the little power provided from the motors. 

Design: 

        While designing the door we needed to take into consideration all of the issues mentioned above. We had to have a robust door that would stay on one track, a door that would not swing in backwards, as well as a door that was light enough that the motor could power it. The initial design was put together in Tinker Cad, but we soon realized that all the parts being printed together meant that the supports would stop the movement, and from my little experience of 3D printing, I knew that removing small supports was a big job. This led us to making the door as separate parts so that we could assemble the door together after being printed. We needed a base, or rather a stand, to prevent the door from falling over into the castle. Connected to this base we had the sockets that we put out door’s axle bearing into. We also had barriers on one of the ends of the shaft connected to the door to limit the side-to-side movement, while the other side had a gear to move the door. We had a separate gear with a hole in it, which would be used to attach to the motor.  

        However, this process was far from smooth. We did not realize that the motors we were using were very weak, and using our first prototype we discovered that the motor is fast, but barely has any torque at all. This meant that the motor could not lift the door even though it was relatively lightweight. On our newer design we had the door turn on vertical axis so that there would not be any gravity working against the motor. We realized that even the friction of the plastic resting together was a big struggle on the motors, and sanding was mandatory to make the door open/close in a reasonable time. In the end we came up with a design that used one motor, gears, and one door. Although simpler than the other designs, it worked, which was the important part. We then uploaded the file to the Flash Print program, sliced it, added auto-supports, and printed the file. Because we had already printed the first door, we knew how the printing process worked, and had both pieces printed on the same day.

Debrief:  

        I personally think that this project was not a complete success, but not a failure either. I think that it could have been improved by keeping the door on a smaller constraint of movement, so as to not let the door touch any high-friction surfaces. Our design ended up working sometimes, but the friction was still too much for the motor. The door was fully capable of opening and closing automatically if the door was on the correct path. We found that many times the door would move to the incorrect position where the friction of the door resting on the hinge and floor made too much friction for the motor. We ended up having a slightly unreliable door but were still proud of what we created. Although we could most likely have created a better project with more time, we still managed to make an automatic door.  

        As mentioned above, the project was not a failure either. All our circuits functioned correctly, and the motor was always able to spin in both directions. We also managed to learn a lot about how we could have improved our door to make it function consistently in the future. We learned about the upsides of printing like being able to create many shapes and designs out of a computer and a small line of plastic, and some of the downsides like how a lot of sanding was required after a print, and how the print could only be as specific as the width pf the plastic. This was a slight issue because we needed very exact measurements on our print, especially on such small print. We also saw that printing can sometimes be weak or flimsy and being made of strings of plastic, a circle will never be truly round and smooth. Not to mention long tubes will very easily fall apart. I think both Tae and I would have had a much simpler time with this project if we had been able to know these things before printing the door. We also learned more about how friction works when working with small amounts of kinetic energy, with the doors we created always having issues with hinges being too tight or loose.  

       In summary, Tae and I managed to make a mostly functional door, and although we were not always able to get it to work, we had our circuits all working, and we were able to learn a lot about making items using 3d printing, Cad software, and much more. 

 

 

Electric House Project Questions 

1: You have three lights bulbs. All have the same intensity when lit. Explain how you can prove to a classmate that they are connected in series by unscrewing one light bulb. Support your answer. 

You can prove to a group mate that a circuit is in parallel by unscrewing one lightbulb. This breaks the circuit for the electricity to flow through, therefore the other lights will turn off. If the other lights were still on, they would have most likely been in a parallel circuit instead, 

 

2: You have three light bulbs. All have the same intensity when lit. Explain how you can prove to a classmate that they are connected in parallel by unscrewing one light bulb. 

When unscrewing a lightbulb in a parallel circuit, it does not fully break the circuit as there are more than 1 paths to run a flow of electrons through. You would observe when unscrewing one lightbulb that the other lightbulbs would stay powered.  

 

3: You have three light bulbs. Two are connected in parallel. This parallel combination is connected in series with the third light bulb. Describe the relative intensity of each bulb. Support your answer. 

In the circuit mentioned above, a parallel circuit integrated into a series circuit can be considered one singular load to simplify the thought process. The current can only travel as fast through the parallel circuit as it can through the singular light bulb, so the current crossing each individual light bulb in the parallel circuit is half that of the current passing through the lightbulb in the series circuit. 

 

4: In Question 3, describe the relative intensities of the two remaining lit bulbs if one of the bulbs in parallel was unscrewed. Support your answer. 

If one light bulb was unscrewed in the parallel circuit, then only one path would remain which would mean that the circuit would be considered series only. The current, rather than flowing through two paths, would only have the one path to travel through and either of the other two lightbulbs being unscrewed would lead to a complete break in the circuit. The circuit being in a series state would mean that both lightbulbs would share the same current passing through them. 

 

5: Outline a step-by-step method that could be used to determine the resistance of the light bulbs in one of your circuits. Feel free to include a circuit diagram of your set-up.  

To determine the resistance found in a circuit, we can use ohm’s law (V=IxR, or in this case R=V/I). One possible way of measuring the resistance in a light bulb in our circuit I by measuring the current and the voltage passing through the lightbulb, then dividing the voltage (V) by the current (I) to find the resistance (R). 

 

6: Using your method outlined in Question 5, determine the resistance of the bulbs in one of your circuits. 

When using the controlled environment of the PHET Circuit Constructor, and by using the average resistance of a Christmas tree lightbulb (8 ohms), the voltage reading in our parallel circuit was 9 volts. The current reading was 1.12 amps. By putting this into our equation of R=V/I, we get a resistance of 8.03571429, which we can round to 8.04 ohms total. Because this is a parallel circuit, the reading is the same on the other lightbulb too. 

Details: 

Circuit: Parallel 

Lightbulbs: 2 

Dry Cell: 9 Volt 

Lightbulb resistance: 8 Ohms 

Voltage: 9 Volts

Current: 1.12 Amps

Resistance: 8.04 Ohms

 

Below is my core competencies reflection on this project:

 

More photos of the project: