Wall clocks, while still certainly useful for keeping the time front and center in our minds, are perhaps less essential than they used to be. After all, each of us caries a precision timepiece in the form of a phone with us constantly, so perhaps where they really shine is as an estimation — or even decorative — device.
For the geeks among us — i.e. myself and those reading this blog — this hard drive chime clock, powered by a NodeMCU ESP8266 board, fills both roles perfectly. The project uses an array of four disassembled hard drives to strike their respective chimes, using the read-write arm actuator connected to a striker assembly. Strikers are controlled directly by an array of transistors in an ULN2003 chip, and the clock features only a single button for user interface.
This single-button interface is possible as the NodeMCU gets the network time off the local network, and a webpage is then used for more detailed control than could be accomplished with a single button. The clock is installed in a semi-public space that holds events and exhibitions, which should be perfect to let a speaker know when it's time to wrap things up!
Check out the demo in the first video below, and a prototype version after.