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  • Dror Margalit

DC Motors are Spinning Round

Working with the DC motor was challenging because it required using a higher voltage than usual. Even though I followed the Lab Notes and made it work, I am still unsure how the TIP-120 transistor works. Before connecting it correctly (with a 9-volt battery), the DC motor spun but did not correspond to the potentiometer.

DC motor and a potentiometer

In the two images on the right, the DC motor spun at a consistent speed or didn't spin at all. On the left, I added a 9-volt battery, making it operate as expected. I must say that I do not fully understand the logic behind it.

No additional power source:

Additional power source:

DC and H-Bridge

Working with the H-Bridge was easier once I understood how to connect the DC motor correctly.

The insightful moment of opening a record player

In these videos, Elyana and I made a record player spin using a 9-volt battery. We simply connected it to the 'positive' and 'ground' of the DC motor in the record player, and voila, it started to spin. When we switched the positive and ground locations, it spun in the other direction.

It was extremely insightful to open a record player and recognize the components that make it. Moreover, making it work using a battery felt like magic, as I could see how the logic learned from the labs is applied elsewhere.

Mid-term project update

Mary, Xiaoran, and Dror

Over the last week, my team and I have been working on the different components that make our experience. Here are the updates:

Two-layered box

We ordered plywood to build a box with two layers. The internal part will have holes for the buttons and hold the Arduino board. The external layers serve as a way to hide where the buttons are, as we want the participants to find them.

Servo motor box opener

At the end of the experience, the participants will be invited to take candy from a box that opens on its own. While waiting for the treasure box we ordered, we made a prototype (seen in the video).

Beam breaker sensor

This sensor will indicate when a hand enters the box.


Since we also have a video component, we also worked on a script that we will film this week.

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Peer-to-peer nose interaction

By Joann Myung and Dror Margalit In this project, we attempted to increase our online presence and create a feeling of proximity. Using PoseNet, we made users control their position on the screen base


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