The watch is centered around the attiny85, a really small eight pin micro controller (just like the arduino, only tiny-er). The attiny keeps the time, and drives the vibration motor. A transistor is used as a motor driver to current-protect the attiny. Even though the vibration motor is small, it needs more current the the attiny can handle. Finally, there is a button to manually request the time. The entire setup is mounted on protoboard and powered by a coin cell.
This project is not only a cool watch, but a really small arduino board! That's right, the attiny85 is programmed through the arduino IDE. More on that later.
Step 1: Gather/buy materials
-Hot glue gun
-Rotary tool or hacksaw
-Soldering iron w/solder and damp sponge
-Arduino uno or similar to program attiny.
-Computer with latest arduino IDE
-USB cable for uno
I chose not to link to distributors like digikey or sparkfun because everybody seems to have their own preference on where to buy parts, and you can buy these at almost any good online store. However, I recommend jameco. Some stuff can be salvaged easily. All are thru-hole.
-Through hole stripboard. (Look for the epoxy stuff, fiberglass is dangerous to cut)
It will be easier to follow this instructable if you use the same board then I did, you can find it at
-CR2302 coin cell battery holder.
-Small push button.
-220 ohm resistor
-3300 ohm resistor
-8 pin DIP socket
-Vibration motor (I salvaged this from an old cellphone, or you can buy one)
-Scrap hookup wire (not much is needed)
For reference throughout the build, refer to the (sloppy) attached schematic