I am scatterbrained. I like to drink hot tea. Oversteeped tea gets bitter. I am easily distracted.
The natural choice was to (over)engineer something with inexpensive hobby-grade electronics. Automatic tea timers are hardly new and people have made them from discarded toasters and K’Nex which I have a lot of respect for. People on this site have been making them with Arduinos and Servos for a long time so I’m hardly the first. This project has three major differences though.
Uses a text display
Clips on the cup rather than free standing
3D printed for a finished look
Due to the printed parts the MATERIALS list is short. Most of the parts can be found on eBay very inexpensively.
16×2 LCD character display
5V Arduino Mini
9g servo motor
Normally open (NO) switch
3 position rectangular male header pins
4-40 threaded rod or metric equivalent
4 @ 4-40 3/8″ bolts
12 @ 4-40 nuts or metric equivalent
2 @ 3mm bolts which are at least 6mm long
2 @ 3mm nuts
2 @ 5mm bolts which are lat least 12mm long
2 @ 5mm nuts
2 @ #4 wood screw
Male USB plug with cord
Small gauge wire
There are a minimal amount of TOOLS necessary for this build
Computer for printing and programming
Small screwdriver for small bolts
Programming board for Arduino Mini
This project requires you to know how to solder and send a program to an Arduino Mini. The program has already been written so you don’t need to write any code. There are plenty of instructions for doing both these things so I won’t go into them here. This is a big change from my tCDS unit which had 72 steps and didn’t rely on previous skills.
Step 1: Start Printing
Picture of Start Printing
There are two files to print. The first is the parts which do the tea dipping. The second file is for the enclosure. The enclosure isn’t strictly necessary and if you chose to construct a wooden enclosure that would add a welcome touch of class to this project.
STL model for parts
STL model for enclosure
The source code for these files can also be found on my blog. Just check out the final posting of this project and look for the links at the bottom of the page. These links will open new windows or tabs.
Step 2: Soldering
Soldering comes next because it will be necessary to attach your communication pins to the Arduino before programming. Since we’re already soldering we may as well attach the rest of the components.
Arduino Minis often come with the header pins unattached which is perfect because they would take up too much room in this project. The only exception is the data pins for programming. These are often right-angle pins and should be soldered to the board.
The speaker used in this project does not have to be anything special. I used a 16Ω headphone speaker and it’s plenty loud. A piezo element would also work but NOT a piezo buzzer. A 5V piezo buzzer could be substituted with modification to the code.
The start switch and potentiometer are both expected to have roughly 6mm diameters for their mounting posts. This is pretty standard for inexpensive potentiometers. If you insist on using a different switch, and I encourage this kind of thing, go to the final Tea Maker page on my blog, download the OpenSCAD code and change the diameter as you see fit.
For the servo, be sure to solder the short ends of the rectangular male header pins so the servo can plug onto them. Alternatively, you could clip off the end of the servo wire and directly solder it to the Arduino.
For more detail: Automatic Tea Maker