Watch Ring (ATtiny85)




About: I like to learn, like to make, like to share.

This is my another wearable project. Makers always like to use something made by their own & I am not different. I was thinking to made a watch ring for a month and finally I made it. It is very simple and you can make easily. ATtiny85 microcontroller and a RGB LED are the main components for the project. Time is shown by the RGB LED using different color. A button switch is attached to the watch and when it is pressed , LED will show you the time.


Let's explain, the first number represents the hour and the second number represents the number the minute hand would be pointing to if it were an analog clock. The green color represents 0 and the blue color represents 1. For example, if the watch flashes 0010 (GGBG) - 0110 (GBBG), this corresponds to 2 - 6, which means the hour is 2 and the minute hand points to the 6. It's 2:30. (Check out the image below for a graphic description!) There's no indication of a.m. or p.m., but hopefully it's clear whether it's 2:30 in the morning or not :) (Inspired by The Nerd Watch).

Image is taken from Nerd Watch.

Do you love resistor? If yes, this ring is definitely for you. The ring for the watch ring is completely made by resistor. I hope you will like it. If you have access to any 3D printer you can made a 3D printed box to fix the battery an PCB. It will make the thing more gorgeous.

Step 1: Required Components

  • AVR ATtiny85
  • LED - RGB 5mm Square (Piranha) (Sparkfun)
  • 3 100 ohm SMD resistor
  • 1 button switch
  • 25 1/4 W resistor
  • PCB board
  • CR1632 Lithium battery (3V)

Step 2: Schematic

Schematic was designed in Eagle. Source file is attached. All resistors are 100 ohm.

Step 3: PCB Layout

PCB layout was designed in eagle. Board file is attached.

Step 4: Make the PCB

I made the PCB using toner transfer method. If you are new in PCB making follow the instructable:

Cheap and Easy Toner Transfer for PCB Making

Step 5: Drill the PCB

I used my hand made drill to drill the PCB. You can use you own or may use Seeedstudio: MINI electric drill kits -161pcs

Step 6: Solder All the Components

Carefully solder all the component to the PCB board you made earlier. You need some experience in SMD soldering for that. Are you new in the field? Follow:

Instructables: How to Solder SMD ICs the easy way

Sparkfun: SMD How To - 2

Step 7: Upload the Program

We completed our circuit. Now it is the time to give live to our ring. Upload the program to the ATtiny85 chip using Arduino as ISP programmer. If you are new you can follow, instructables:

ATtiny programming with Arduino


The program used for the clock is taken from the instructables: The Nerd Watch. and slightly modified. So for the program all credits goes on to The Nerd Watch. To know how the watch works follow

Step 8: Make the Ring

I used 1/4 W resistor to make the ring. I thing it the first time someone made a ring using resistor. 25 resistors is required to make the ring. You can used different colored resistor if you like. To make it just follow the images attached herewith.

Step 9: Finalized the Ring

Use a diagonal cutter or nail-cutter to cut the lags of resistors. Your ring is now ready. The ring is flexible enough and you can bend it easily.

Step 10: Attached the Coin Cell to the PCB

Now, attached the 3 V coin cell to the PCB board using hot glue. Be careful! Don,t attached the battery side to the PCB directly. It will short the board. Two thing must be insulated from one another.

Step 11: Attach the Ring to PCB

Now attached the resistor ring to the PCB board as like in figure. You may use hot glue to do the job.

Step 12: Wear the Ring

Congratulation! You successfully mad the thing. Now it is the time to enjoy it. Wear it to the finger you like.

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    12 Discussions


    3 years ago

    cool.... WOW


    3 years ago

    very impressive :)


    3 years ago

    not quite clear how resistors in ring are connected and then cropped


    3 years ago

    I like your handmade drill! Good use of an old motor, and I'll bet it works great for drilling small holes like that! Nice idea as well, using resistors for the ring!

    1 reply