[PHY] A7: Halloween Midterm, or Tom Igoe Was Correct – Long Wires Are Long


The goal of this assignment is to show that you can make a simple interactive system with physical controls, and that you can keep a user engaged with your system.

This year, the midterm project will have a Halloween theme. You should make a device or experience for a Halloween party.


My partner Gil and I started discussing what we wanted to do right away at the end of the class when this assignment. Gil was already toying with this idea of a projection installation and I was interested in creating spooky sounds, so we decided to do a spooky ghost projection installation. Gil was keen on using Isadora, a real time programming software that deals with manipulations of video, and his confidence made me interested in using it.

We knew we wanted an actress/actor, so we asked Danqi, our fellow physical computing student. After she agreed to participate we knew that the project is a go and the only thing to figure out was how to accomplish our goal.

The idea

All in all, this was the idea:

  1. There is a hallway and the ghost of 721 Broadway is just “lurking” in an idle position.
  2. The victim crosses the far Ultrasonic Module HC-SR04 (simply UM from now on) and the ghost calls for the victim to come forward.
  3. The victim crosses the middle UM and the ghost asks for help by reaching out the hand.
  4. The victim crosses the final close UM in an attempt (a hopeful one) to reach out to the ghost and the ghost disappears.
  5. There was an idea to have another version that just a jump scare, but we thought it was too basic.

Process and problems

Overall, Gil was the one who dealt with code (I looked and helped troubleshoot when needed) and I was the one dealing with the physical wiring of it all. Of course, Gil was also the one who managed Isadora and the projector, as that’s his forte. When it came to video editing, we did it together and my rusty-at-this-point knowledge of Adobe Premiere came in handy.

The first problem we had is that the UMs we bought weren’t working at first and it turned out to be because they were rated at 5V and not 3V like the original UM that Gil owned and tested on. After we figured this out, we used coin cell holders and put in two coin cells that together made up 6V. To reduce the voltage we used a 7805 voltage regulator.

The second major problem was putting it all together. We used the hallway of ITP that’s closer to the kitchen as our area. The long distance made it all harder. We wanted to conceal all the wires and it largely succeeded.

There was one weird weird problem…

Tom was right, don’t mess with long wires! The middle UM was connected to the far UM’s Arduino Nano 33 IoT and because of the length it didn’t ground properly. It was the last piece in our puzzle and somehow nothing worked. We double, no, quadruple checked everything and the sensor wouldn’t ground unless we physically touched the voltage regulator. Made zero sense because the set up was exactly the same as the close sensor. Then we connected a wire from it to a physical metal pipe to ground it all. \


To Gil, for being an amazing, responsible, and creative minded partner.

To Danqi, for becoming an actress for us and suffering the intense heat from all the lights and putting on a tonne of make up.

To Tom and Rob for letting us book the room.

To the rest of ITP for being supportive! Love y’all!


More images and videos will be added in the future.

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