This project aims to help solve the problems of forgetful roommates/kids or a faulty fridge. You know how sometimes you can "close" a fridge but it doesn't really close quite all the way? Well that was the main inspiration for this project. Not only will it detect when the door is left even slightly ajar, if this or anything else causes the fridge temperature to fall below a safe temperature, then a second alarm will trigger and its users will be notified of this event. Though many new fridges nowadays have a system similar to this built into it, sometimes you are in a living situation where you either cannot afford these new fridges or where appliances are provided and they are a little out of date. Nobody wants food poisoning, so this project helps ensure safe containment of food. The argons used in this project will not only graph the temperature data in real time, but also communicate when one has an issue and then is able to send the user a message via an IFTTT notification.
1 / 4 • Temperature Sensor
1 / 2 • Door Sensor Circuit, Red Circle Represents Physical Alarm
The door sensor circuit utilizes a PNP transistor acting as a switch between the digital output from the Argon and the 5 Volts coming from the VUSB pin. This was done due to the voltage requirements needed by the physical alarm. The specific transistor used here could be swapped out with another kind or another component completely, as this component could sometimes get quite hot if the alarm was running for too long. The temperature sensor needed an additional 2kohm resistor across the pins of the sensor board in order to read values from the argon. The temperature sensor also required the use of additional libraries in order to accurately record the temperatures in Fahrenheit.IFTTT Applets
IFTTT applets were made to send both users notifications when either the fridge door was open or when the temperature got too high. This makes it easy to know when things are getting out of line even if you aren't home.ThingSpeak Integration
Live Data: https://thingspeak.com/channels/1577432
ThingSpeak was used to graph the temperature data over time, so one could look at fluctuations and maybe root out the cause of their food going bad. Using a simple webhook, data from the temperature sensing argon is published to the console, and the webhook finds the specific temperature event and publishes the data to the ThingSpeak graph every 10 seconds.Communication Flowchart
This is a brief video showcasing the circuits used as well as what the alarm looks like in action. Feel free to comment with questions, suggestions, or anything you liked about the project. Thanks!