Monday, April 10, 2017

Week 12 Justin Schafer

Rube Goldberg Trebuchet:

For the Class Rube Goldberg project I decided to use a catapult. After researching different types, I settled on the trebuchet due to the physics that would be interesting to recreate on a small scale. I found the optimal ratios for the different components as well as a sturdy, simple design.

Autodesk Inventor Schematic:

For the electronic side of my design, I have two bread boards, one that is covered and one that is not.
The first one is covered by the target, in order to keep it dark. However, a small amount of light is allowed in through the funnel. When this hole is covered, the Photoresistor will increase in resistance, which will then activate a relay after being converted into the correct voltage via a Transistor and Operational Amplifier. The relay is then connected to a 555 Timer, which has its pulses counted by a Binary Decimal Counter. The output from the counter is transferred to the other bread board.
The second bread board converts the outputs of the Binary Decimal Counter to 5 7 segment displays that spell out "gOAL!" (Has to be lowercase g due to limitations of 7 segment display.)
Bread Board Circuits:
In order to ensure that the projectile of the trebuchet does not miss, the proverbial "side of the barn" approach was used. A box was made to completely cover the first bread board, and on top of it, a large wall was made. This large wall was then connected to a hole in the top of the box via cloth. This created a soft landing for the projectile, mitigating most of the momentum of the projectile and preventing it from bouncing out. When the ball is sunk into the whole, the photoresistor activates the circuit.


  1. Loved it. I cannot wait to see your 3d printed parts. You need a technical circuit drawing.

  2. The 3d printing catapult idea is cool and using a shoot/cloth using to collect to shot ball to cover a photo resistor to activate your electric circuit is neat.

  3. That is awesome that you are 3D printing your trebuchet. I am excited to see how this works out for you. Is it going to be hard to get the funnel to line up directly with your photo sensor each time, or are they somehow in a fixed position? The cloth was a great idea to reduce the chance of missing your target.

  4. You have an awesome idea and I'm excited to see the finished product, but you may want to include how the catapult would be triggered and how your circuit will trigger the next machine. Other than that great Idea!

  5. Good thinking to make your photo resistor more relaiable Im sorry to hear about your 3D printed parts I hope that you are able to come up with a quick fix! I think you definitely earned the complexity points!