Automated Fish Tank

Prior to my winter break this past year I planned a month long trip to backpack around Nicaragua. The problem with going on this trip was I had no-one to take care of my fish while I was gone. To mitigate this dilemma, I decided to engineer a system that could take care of my fish for me. This system had to include a way to turn on and off the lights, and a way to feed my fish at the beginning of every morning. The following is what came out of this endeavor:

1. I first began with the CAD models that would do the feeding. All of the CAD was done using Fusion 360. The concept focuses on using a continuous servo to spin a disk containing pre portioned food similar to a gumball machine. After many failed prototypes, I had a working prototype.

2. Once CAD was completed, I began picking out electrical components to use. I knew I wanted to code the project in C, so I picked out an off-brand Arduino Leonardo. The servo I had was a 180° servo, so I also purchased a continuous servo that utilized the same dimensions. These small servos allowed the system to maintain a very small and light profile. Lastly, I purchased a relay that would easily separate the 12V light from the 5V powering the Arduino. 

-Implementing the light in this case was fairly difficult because it was originally operating via a touch-capacitive button. This was hard, because the PCB would not allow me to alter the switch, so I had to mimic a small change in capacitance via an impulse sent from the Arduino.

3) The last step to finishing this project was tying everything together with code. The code for this project was fairly straightforward, the fine tuning of how long to rotate the continuous servo was the trickiest part.

-I commented thoroughly throughout the code so it is easy to follow. The bulk of the code is simply a for-loop repeating the actions each day. 

-To have full trust in this system to take care of my fish, lots of testing was done.

-Luckily it all worked very well and I was able to go on my trip with piece of mind that my fish would be alright on their own.

Note: After this trip, I studied abroad in Sweden for 5 months, and my fish tank maintained itself perfectly during that time as well. The only human intervention was my mom topping off the water every few weeks for me.