LetB was my first project based on Arduino. I have done three versions, starting with the prototype board and 5mm LEDs glued onto the plastic board and finishing with complete custom-ordered PCB and addressable LEDs for RGB effects.

The last two revisions featured a speaking option to announce the time. Firstly, audio processing was done on Atmega which was not the best option. The last upgrade featured a separate player controlled by UART.

All revisions came with an optional Bluetooth feature to connect with a smartphone to change time, adjust brightness, set speaking options, and later the colors of the letters.