DIY Homemade Portable Arduino Coffee Coaster With Temperature Indicator LED

Many things happen just by drinking coffee. Big business successful ideas come out while people are chatting having coffee. I love having coffee especially when I'm in the office. I'm pretty sure everyone out there loves coffee. But when I make coffee, i can't drink it straight away because it is too hot. If i leave it for awhile it will get too cold and becomes very disgusting to drink. So i just thought of doing something that could tell me that my coffee is at the right temperature for me to drink. In this way, I could avoid burning myself at the same time enjoying my coffee. Knowing the right temperature makes your coffee drinking experience very memorable especially if you share with someone you love.

This instructable is based on Arduino tutorial on temperature sensor. I made a simple hack on the code to make the circuit behave the way i wanted to.

The circuit consists of LEDs which represents the different level of temperature. In my trials, I am happy to drink my coffee when only 5 LEDs are lit but different people have different immunity to coffee temperature, so basically you have to determine your right coffee temperature based on your preference. I am using TMP36 to detect the temperature of the from the bottom of the coffee cup. The Arduino Uno processed the data from temperature sensor and turns on the LED at preset temperature.

After few trial, I find the project to be effective, so I am planning to get this project into the next level. Make it as small as possible so that everyone can use it at home or office and avoid coffee burn while enjoying coffee.

I had an old lunch box which had not been used for while. Arduino Uno sets perfectly protected inside the box. A circular coaster where i can place the cup. I put a small switch at the bottom of it so that when a cup is placed at the top of the coaster it turns on the switch and turns on the circuit and start reading temperature. TMP36 is placed at the upper lid of the coaster to get it closer to the bottom of the cup for better temperature sensing. LEDs are used to display coffee temperature at preset level and provides a visual temperature reading. When all LEDs are lit up, it means a very hot coffee, less LED, lower coffee temperature. A 9V battery powers the whole circuit. In my next project I will use a 3V battery and smaller circuit to reduce the prototype size at the same time try to achieve longer battery life.

Enjoy....

Start by placing the coaster at the top of the lunch box. make sure it sits perfectly. I cut a little piece in my case to achieve this. I opened the coaster and fit the temperature sensor with sticky clay to hold it in place. I have soldered the small switch and placed it inside the coaster so that it will turn on the circuit if anything is placed at the top of the coaster. Make sure the coaster is moving freely.

Wire up the arduino, LEDs and temperature sensor. Previous knowledge on Arduino starter kit is required to do this build. I have attached the full circuit diagram for you follow. I have used 220 ohms resistor for each LED. You can use any LED color as you like. Download and load the codes to your Arduino.

Enjoy.