Sunday, April 10, 2016

Week 12

Blogsheet Week 12:

This week’s blog sheet will be individual but you will post it on your group blog.
Your individual Rube Goldberg (RG) setup should satisfy the following:

1.       Use at least 2 of the following components:
a.       Transistor
b.      OPAMP
c.       Relay
d.      Temperature sensor
e.      Photosensor
f.        Motor
g.       Display
h.      Strain gauge
i.         Speaker
j.        Microphone
k.       Solar panel

2.       Use a new circuit: It can be a modification to one of our lab circuits.

3.       Let your system complete its task in no shorter than 10 seconds.

4.       Make sure you are compatible with your preceding and following RG stage.


1.       Provide the computer drawing for your individual RG setup.

2.       Explain your setup.

The whole device is triggered by an object landing on the force sensor. The input voltage goes through the oamp and is multiplied by a non-inverting amplifier. This new input voltage is sent to the relay. On one end is a led that is already on on the other is a motor turned off. When the relay is triggered the motor turns on. This begins winding a string attached to a small cardboard flap that is keeping the ball on top of the ramp. The flap is removed and the ball rolls down the ramp triggering the next device.

3.       Provide photos of the circuit and setup.

Image 1: Starting setup with force sensor as trigger

Image 2: Add LED to one end of relay

Image 3: Full set up
Image 4: Test one of entire set up

4.       Provide at least 2 videos of your setup in action, one being a failed attempt.

5.       What failures did you have? How did you overcome them? 
One of the major issues I have had is being able to use the force sensor to trigger the relay. The problem is getting the input voltage high enough to trigger the relay. I am trying different resistor combinations in a non-inverting amplifier set up.



1.      Provide the computer drawing for your individual RG setup.

Image 1: Schematic idea #1

Image 2: Schematic idea #2

Image 3: Physical Rube Goldberg setup

2.      Explain your setup.

Idea #1: A solar panel will start the circuit when it is revealed to a light source from Andrew's machine. The capacitor will build up and the capacitor voltage will start the dc motor. With Idea #2, the voltage from the solar panel will transfer to an op amp, which will help trigger the relay. When the relay switches, it will turn on the 6V dc motor. The motor will begin to spin, pulling a car that is attached to a wire. On the front car, there is a needle. The car will drive into a balloon, popping it with the needle, and hope that there will be enough force from the balloon pop to start a domino effect (the balloon and the first domino will be touching each other). At the end, the last domino will fall onto the force sensor of the next Rube Goldberg machine.

Update: Decided to go with Idea #2

3.      Provide photos of the circuit and setup.

Image: Breadboard layout of Idea #2

Image: Breadboard with solar panel of Idea #2

4.      Provide at least 2 videos of your setup in action, one being a failed attempt.

Video 1: AJ's failed test run

Video 2: AJ's successful test run

5.      What failures did you have? How did you overcome them?

I was having issues starting up my motor; since it's a bigger motor, I need to supply enough voltage to make it spin. I might have to add in an opamp (non-inverting). I wanted to use a photosensor to start the circuit, but had to use a solar panel instead. Before I connected the motor at the end, I was measuring about 6.5 V, which is enough to make the motor spin. But when I connected the motor, the voltage significantly drops to around 35 mV. It's becoming a reoccurring issue; probably something simple to fix though. 

Update: I was able to make a smaller motor run compared to the larger motor. I switched the large motor out for the small one since Andrew wasn't using his anymore for his machine (as of today at least). I fixed the values of the resistors to have a higher gain to trigger the relay and move the motor. However, now I need to make the physical part of my machine and test it out this week. 



1.      Provide the computer drawing for your individual RG setup.

2.      Explain your setup.

Initially the solar panel will be covered that way the circuit will not be functioning. Once the solar panel becomes uncovered it will transform the light into a small voltage, which will be amplified by the OpAmp enough to trigger the relay to switch. Once the relay switches, the +5VDC will be applied to the motor which will turn it on and raise the flag (and hopefully trigger the next circuit to activate.) The only change that might be made is to install a current limiting resister between the motor and relay.

3.      Provide photos of the circuit and setup.

Image: Andrew's breadboard layout

Image: Andrew's nifty wheel :)

4.      Provide at least 2 videos of your setup in action, one being a failed attempt.

Video 3: Andrew's failed Test Run

Video 4: Andrew's Success Test Run

5.      What failures did you have? How did you overcome them?

I needed to play around with the resistor values to get a high enough gain to move the crane setup. I also switched out my motor because the crane will be more efficient to pull the string and raise the flag.


  1. Vince; videos are missing. Better drawing of your setup.
    AJ; your drawings are separate. Try to make it look one setup.
    Andrew; I like the wheel! Good job.

  2. AJ: I like your idea. Mostly because we both involve a balloon popping in ours. But the way you get the balloon to pop is interesting and cool. Do you think the smaller motor will have enough torque to pull the toy car? I hope your balloon pops!!! -Matt

    1. Thanks, Matt. I think the motor will have enough torque to pull the car, but depending on how fast the car goes and what angle the needle is at, it may or may not pop my balloon. I was testing it earlier in my room, without the motor, and the first run my balloon didn't pop. But when I changed the needle's angle it popped and the dominoes fell just like I planned. Hope yours works out as well!

  3. Vincent, I like the setup of your RG project and I feel your pain with the pressure sensor, I had some of the same issues as well. What worked for my was adding a transistor after my OpAmp to start my motor but I'm not sure that will work for your relay.

  4. Andrew-
    I like the circuit setup and the final wheel from it. Hopefully when the wheel brings up the flag that it will set off the next project!

  5. Andrew, I like your idea because it includes the solar panel which we never used in a lab. That shows that you are taking initiative and that's great. However, I did see one small issue with your schematic. It could be fixed by either adding pin outs to your components or swapping a wire. The issue I am referring to is with your relay. According to the data sheet the top right should be the output if your input voltage is less that the threshold voltage. This would mean your motor would be on initially and shut off once your relay flips.

  6. Vince, this seems like a flawless design that may not be extremely complex, however, has a much less chance for failure while operating. Also, it's good that you discussed how your device triggers the next persons.