Introduction: DIY Hot Beverage Monitor - Using the DS18B20 and Arduino Nano

About: Expert in nothing, interested in everything.

My girlfriend always have a problem that she burns her tongue when she taste hot drinks. Then I started thinking, maybe I could create a device that prevents her burning her tongue, so she can drink her tea and it always have the perfect and wanted temperature.

Two things I wanted to learn about in this project was how I could use the temp sensor DS18B20 with Arduino and how I could make a easy battery function with a batterypack on Arduino.

Here is how it works!

Red light - to warm

Green light - prefect

Blue light - not connected

The project may not be something everybody want to make. But I want to show you what I made. Therefore I make my project as an Instructable so you can see my progress and see how I was thinking trough the project.

Check the next step to see how i made it.

Again, sorry for my bad English and I hope you like my project.

Step 1: Parts

Here are the parts i uset to complete this project

9x Small magnets

1x Arduino Nano

1x Batterypack

1x Temp sensor

1x 4,7k resistor


1x Button

3mm steel plate


Acryl plate



Leg pads

Brown paint

Step 2: Designing and Making the Device Housing

The first thing I started with was designing. I designed the device in Google Sketchup. First I started making two circles of wood there one circle was hole on the inside. Outer diameter 10cm, inner diameter 8cm. Thickness of the wood was about 1cm. Then I made a ring like the one wood ring, with hole inseid. Then I stacked these up on each other and got a round box without a bottom. To make a bottom I cut a steel plate to a circle so that it fits with the other circles.

After that I used wood glue and super glue to the layers together except the steel plate.

Step 3: Electrical Parts

This box is really very simple, made with some common electronic parts.

The battery box is an old powerbank I found lying around. I opened the cover and used the battery and circuit board.

I glued 4 RGB light inside the box that will alert about the temperature in the cup.

I add a simple button to turn on the device. It is connected between the battery and the Arduino.

I removed the USB connector on the circuit board for the batterypack and soldered 5v + and - to Arduino pin Vin + and Gnd-.

For easily charged up device, I drilled a hole in the steel plate so that the micro USB port on the circuit board to the battery can stick out there. Then I easily can charge the device with mobile charger. Also drilled a hole to the button.

See wiring diagram.

Step 4: Connect Cup and Device

To communicate with the box I had a big problem figure out a solution. Eventually I found out that magnets were the solution.

To make the cup, I took a cup and drilled a hole in the bottom, then I took a 3 wire temperature sensor and threaded through and glued to the bottom. Then I made 3 circles in different size and soldered the 3 wires from temp sensor to the rings. To get the signals in the cup I mounted 9 magnets. I drilled holes for these on top of the unit. These holes are lain up against the rings on the cup. The one magnet in the middle is + on temp sensor, the 4 magnets in around the middle is - and the 4 outer magnets are the signal. Using food graded hot glue under the cup.

It's hard to explain how I did it but i hope you understand when you see the pictures.

Step 5: Arduino Code

I'm no expert in programming. The code is very simple. It reads the temperature of the cup and based on what the tempertature is use different colour to alert through Arduino and RGB lights.

Blue light means that the cup is not connected. A green light indicates that the beverage is ready to drink. A red light indicates that the beverage is too hot and you have to wait. I myself have the ability to adjust the temperature I want in the program.

Step 6: Last Touch

The last thing I did was to paint device in a brownish paint. To add the bottom plate I glued four nuts inside the device so I could use screws to add the bottom. To the end I only used two because it wasn't space for all four. To get the box steady I put on four chair leg pads.

Hope you liked my project.

Make sure to vote in the contest if you want !


Peder W

Home Hacks Challenge

Runner Up in the
Home Hacks Challenge

Sensors Contest 2016

First Prize in the
Sensors Contest 2016