Final Show and Tell May 3

My partner Cailey and I met earlier this week to work on the case for the final project. It is basically a larger (2.7'' x 2.5'' x 2'') rectangular version of my box design.

Case for final project.

We taped the battery holder to the lid. This way we would have better access to the batteries. When we folded the sides we noticed that the case was a bit too small for the lid with the battery holder to go in. We tried transforming the sketch by 10%, but after cutting it out, the case was way too big. It was frustrating to figure out a way to make our case design work since the project would be due during class. We decided to see our circuit the next day before making further adjustments to the case design.

On the last day of class we finally got to see our circuit (size and function). 

Oscar's sketch of the sound sensor/ volume detector.

Image of the circuit. The large op amp (black rectangle) is equivalent to 4 smaller op amps. When the circuit detects a loud noise the red LED will light up. The circuit must be reset by passing another magnet over the magnet on the circuit (turquoise wires on bottom of image).  The potentiometer (blue and white square on right) can be adjusted to make the circuit more or less sensitive to noise. 

We cut the breadboard making the circuit roughly about the same size as the battery holder, but still needed to make the case. We added stars along the hinges to allow the microphone detect noise volume, and to enable us to reset the circuit. With little time left, we cut out the new design but the hinge on the case broke. Therefore we went back to our first case cut out and tried enclosing the batteries and taping the breadboard to the lid. Cailey placed 2 pieces of metal inside the battery holder and soldered the wires (red and black)  from the breadboard to metal sheets.

Although our vision of having a streetlight with a red and green light (red for loud noise and green for indoor noise) changed as we progressed, in the end the circuit functioned perfectly and still needed a case. I learned how important it is to have the actual or drawing of the circuit to advance in the project design. By not having the circuit, we were not able to take into account the size of the case or foresee potential issues.

It was interesting to see the finished final projects of my other classmates. Essie and Frances made a dice that lights up red or green when you turn it. They designed their case by making 2 channels for the batteries to slide back and forth. The battery holders had metal sheets wrapped around the ends. As you turn it, the battery holder slides making the metal sheet touch the LED wires which causes it light up. The case design was quite amazing, especially since it was done with acrylic (acrylic breaks easily) and no screws.

Light up dice by Frances and Essie.

Hannah, Erin, and Kelsey made an interactive Harry Potter light-up pop-up book with multiple pages and a fun story line. I thought their project was very enjoyable and I could tell that they spent numerous hours working on coloring, cutting, typing, and pasting. On the first page (image below) the lights behind the candles flicker as you pull down the owl. This is due to the owl blocking the photo receptor above Ron's head. On the next page they used red LEDs to light up the cats eyes. The final light-up page used red and green LEDs which alternate depending on whether or not you turn the 2 switches off (this is directed in the story line). Their book had to be connect to the power source since the lights needed a high voltage to shine brightly. Most of their circuit was below the cardboard cover supporting the book.

The first and my favorite page of book.

This concludes the semester. I've enjoyed exploring engineering and believe all of us have acquired knowledge about circuits and the design process.

No Circuit and No Case... Yet April 30

Once again, Cailey and I decided to try out a new design for our final project since we are having trouble making our current case design which is an alteration of Cailey's first box design; the 1/8'' delrin melts with the wrong laser settings so the holes for the screws get ruined. We spoke with Oscar and he suggested that we should try Kelsey's lantern case which is sturdier and can be easily adjusted to fit our project. 

Kelsey's Lantern Case as an esp.

During class, we made the battery holder for 2 AA batteries (Kelsey's design was for 3 AAA batteries) and the bottom of the the case; Oscar will continue to work on the complex circuit in his office at Olin. We wanted to dedicate our time in figuring out the best way to increase battery contact which was a major problem for many of us in the lantern project. The way we were going to increase battery contact was by using Frances' and Essie's method of warping a piece of metal with a hammer into a small mound. This way the flat node of the battery would easily touch the metal piece.  The plan was to make a sandwich; bottom piece, metal sheet, and battery holder.

Before warping the metal sheet, Oscar realized that our sound sensor circuit would need 5V instead of 3V which would require at least 4 AA batteries. This meant that we would have to make further adjustments to Kelsey's lantern case (make it bigger) and that we would have to worry about contact between the four batteries and our complicated circuit. Thus we were back to square one, no case and no circuit to work with.

The good news was that Oscar allowed us to use a manufactured battery holder instead of designing one because there is only one class remaining. This eliminated issues with battery contact. We just need to create a new case design that would fit a 2.5''x 2.3'' battery holder and the invisible circuit. To keep things simple, we agreed to use my box design from the first project.