Fridge Deodoriser

thingiverse

I designed this deodoriser a few days ago for #iceboxchallenge. Tested it over several days and found it effective in my old refrigerator with poor airflow. I tried various materials like coffee grounds, lemon peels, and tea leaves with mixed results, needing large quantities to see an impact. However, using active charcoal or baking soda was more effective if air circulated slowly through the material for a few minutes several times per day. For this reason, I settled on this design that requires minimal space. This device consists of two parts - a battery compartment at the bottom and a fan-controlled area above. The fan is activated by an LDR sensor that detects when the fridge door opens or closes, allowing air to flow in slowly through the material contained within. When the fridge door is open, light enters the sensor and turns on the timer, which then switches off the fan after five minutes. The process repeats each time the door is opened. Charcoal or baking soda alone can be effective as deodorisers but combining them with slow air circulation yields better results. Using a 40mm 12V fan with low voltage rating was necessary to prevent draining the battery faster than required. Although fast-moving air seems efficient, it might overpower the absorbing materials' ability to remove odours. The LDR sensor proved simpler and more straightforward for this build than other timing devices like programmed timers. With the fan only needed a few minutes of operation each day, an added bonus was low power consumption. When in standby mode, it consumes less than 0.2mA using CMOS 555 chips. Normal NE555 chips require more current but work equally well. For the battery, Sanyo Enerloop rechargeables with lower self-discharge rates are recommended due to longer battery life, lasting approximately two months. When charging is required, an LED indicator will illuminate immediately upon opening the fridge door if it has run out of power. As a parting update, I included STL files for a container and lid for baking soda absorption materials which may need replenishment or replacement after extended use. The project consists of five main components that users can easily assemble with minimal technical knowledge using an ordinary hobby kit - these are top cover, bottom section, central housing unit for the fan, light sensor and battery assembly, and simple electrical wiring for control purposes only. Important considerations: - Do not forget to attach 555 circuit with CMOS IC like TC 555 which reduces stand-by current and enhances longer lasting of recharging batteries