Motive & Inspiration: Arduino Litter Box Fan
It is time to admit that my cat is literally taking over our lives (me and my husband). We've been thinking of innovative ways to manage handling our cat's litter. We've upgraded the litter box, we've changed the litter type to natural wood pellets, and we're considering changing the lower compartment to an aluminium or stainless-steel box to eliminate bacteria and hence the smell. We only have one bathroom which all of us share and let's say that the litter box odour is becoming a bit of an issue for us. Sprinkling some backing soda helps a bit but never fully eliminate it.
That's when we thought of creating a smart ventilation system for her litter box. While going through Instructables.com, I found this simple Arduino Litter Box Fan which is a fan activated by arduino.
Arduino IDE
Arduino Uno 3
Breadboard (also mini)
Microwave Motion Detection Sensor (RCWL-0516): This sensor will detect if the cat is inside the litter box. This will help turn the fan on and off when the cat is inside, reducing unnecessary energy use.
DHT11 (Temperature & Humidity Sensor): This sensor will help detect the temperature and humidity inside the litter box to determine if ventilation is needed (if it's too warm or humid).
Mini Fan (5x5cm 5V DC): This will be the primary ventilation system for the litter box.
LED: to indicate whether the fan is active, or the system is running.
5V adapter (better operate on 9v batteries)
Jumper wires
330 Ohm Resistor
Software & Componenets
Reviewing circuit design and code in lecture slides
The original project's operation was, however, different from what I wanted as it worked by sprinkling baking soda near the litter box in an under-sink cabinet rather than ventilate the box. So I decided to refer to the 'smart home' lecture slides on the portal. I only used Tinker CAD to draw the circuit diagram (Fritzing wouldn't work for some reason). I also referred to the same slides for the code. After that, I built the circuit using a wiring diagram that I created on Tinker CAD. I connected the adapter to the power outlet and connected the Arduino board to my computer to upload the file and test how it worked using the serial monitor. The serial monitor also helped me with calibrating the humidity threshold needed for the system to work.
Electric circuit making and fitting into enclosure
The real fun was in designing the enclosure. First, I drew the outline of my cat's litterbox's 'ceiling' where the system would be installed using a pen and the cardboard base. After that, I added the circuit and started marking the placement for each compartment using a screwdriver to pinch holes and a pen to draw outlines if necessary.
Next, I created slots in the base to fit thick (1cm) cardboard walls to hold and protect the system. Openings were added for the light bulb and the power adapter. These slots were also protruding beneath the base to fit in the litter box top opening. An empty toilet roll was placed above the dc fan acting as a duct attached to the system's top cover which fits between the cardboard walls.
Lastly, the base was cut with a 1 cm fillet away from the walls and extracted from the main cardboard used to create it.
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I would have preferred to use the MQ137 Ammonia Sensor as it would have been more suitable for this project but I did not have the compartment
Coding: As mentioned earlier, the existing project did not provide any code so I had to build one on my own. I resolved to the lecture slides, the internet, and my notes as reference.
Cat Litter Box Ventilation System
Cat Litter Box Ventilation System (circuitin action)
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