[Thu Apr 12] Lantern Thid Day + Engineering Weekend

I had an interview today so I went to class late. Apparently Essie over napped, so it turned out that I didn't get that behind.

Essie successfully built a battery case that fit well. But because we trashed lots of our models when we cleaned up, I couldn't find the model at the beginning of the class any more. It looked pretty much the same as the next picture except for it did not have wired connections.

With that, we start thinking about ways to connect the batteries together. We cut a piece of metal and put it inside the battery holder. We didn't like it that much because it is very sharp and not aesthetic. But no matter what, we realized that in order to connect the two batteries together, we need to leave some space for wires/metals (whatever we decided to use), so Essie went back to lengthen the case. In the mean time, Oscar said that since our battery holder was well-designed, we could just build our lamp on top of the battery holder instead of putting it inside another box like we were thinking about before. Essie and I decided that was a good idea because that would make our lantern much smaller. We got rid of the box idea and decided to build our circuit on top of the battery holder.

Since Essie and I were both late, we didn't get much done during class. Therefore we met up on Friday and started our 11 hours' engineering party (a couple hours more for Essie...)

We started our model on Thursday and decided to only use wires to connect the batteries. 

(We had so many models that I forgot the sequence of our progress. This might be a later model with lengthened body because of reasons that I would talk about later, but the whole structure was correct.)

As shown, we used a piece of wire going through the left side of the battery case and connect the negative end of one battery with the positive end of another battery. (It is not very clear in this picture, but if you look carefully, you can see a small piece of wire outside the left side of the battery case.) On the right side of the case, we had two extending wires connecting the positive end of a battery and the negative end of another battery. We thought it looked prettier than having metals stuck in the case and we tested this with the circuit that I built on Monday. After several adjustments of connections, IT WORKED!

Here is the back of the case:

That was great, except for we realized that the borders (left and right piece of the case in the first picture) was still a little tilted. Therefore, Essie went to lengthen the case.

Meanwhile, Essie documented our design process of the battery holder:



These were all the little pieces that Essie tried. We definitely worked hard, although it was not until later did we realize how a little mistake would lead to adjustments of all other pieces...





At some point, we decided to move on to the electrical part. I was excited because I got very lost looking at the complex Inkscape that Essie was doing and could contribute a lot more on circuits.
On the left side is our circuit diagram.

We drew the holes on Inkscape using the measurements that I took last week. We documented our data as shown on the left.
We made all numbers smaller than measured because we knew that the laser cutter was going to cut bigger holes.

Except for the holes were too small that wires couldn't go through... The dimension of the three holes for the switches was also off. I poked for 20 minutes and gave up and decided to fix the holes...











This was my second design.
You can't really see the difference but I changed the holes to be 0.035 inch (switches) and 0.032 (resistors) and 0.030 (LEDs) and adjusted the distance between the three holes of the switches and cut again.



I poked for another 20 minutes and finally got all the holes out... (Although later I developed a great hole-poking skill, so later assembling became much easier at the cost of breaking my nails...) Anyways, that was exciting... to finally have a sheet to build circuit on. Therefore I took materials off the breadboard and start building the circuit on acrylic.

The circuit design was easy enough, but the actual building part was a lot harder than building a circuit on breadboards... The biggest challenge was connecting wires, especially since our design was so small. I guess I just needed more practice. I started with the circuit with the yellow LED and tested with the battery model. It worked. Then I went on to connect the green LED circuit.

After an hour, I got this:

(From above, it was connected with the battery case, but we took it out before I got to take a picture...)

(From the bottom)

I don't understand why that took an hour... all I remember was my fingers really hurt... At that point, I was doubting the easiness of manufacturing our lantern... But I had fun building this circuit and finally understood how Essie could keep working with Inkscape for hours. I think I could spend hours building circuits too :) We turned off the lights and tested how bright it was - definitely not bright enough to read... but at that point, Essie and I decided to deal with this and thought it's good as long as they light up...

While I was doing this, Essie worked on the battery case again. She coiled the wires and made a spring inside the case.

She also did more work on the extending wires. Even though the model with purple skin wires we had before was prettier, the connection was not as good as this one. But again, manufacturing could be tricky as you have to manually coil it.

We brought our two pieces together and started to think about how to integrate them into one piece. We decided to lengthy the side the of the battery and make an additional layer on top of the battery case. We could have the top layer for the circuit... sort of like the picture on the left... except for not titled (of course and prettier).

This is a picture taken from the top:

Half an hour later, our design came out. It would essentially be a little box. On the top layer, we have the LEDs and switches (we decided just to leave a split for the switches instead of three holes to make our life easier). The resistors face down towards the battery with legs coming out to be connected with the LEDs.

Finally we added our arch design. It will eventually look like this! So cute... I was going to build the circuit with the new model while Essie kept working on the case. However, I couldn't find extra switches and the two switches we got were already soldered
with a bunch of wires... I will work on the circuit once we get more switches.

I took a picture of the first sheet of acrylic we used... These are all the models we did... We were running out of our second sheet as well...