Sand Clock to Laser Time Writer conversion kit
In the Sand Clock, every minute, two vibrator motors shake the sand to erase the time before writing the new time. To avoid the noise this causes, Elektor Labs thought of replacing the stylus and the sand by a small laser module (under 5V) and a sheet of phosphorescent self-adhesive paper: the result is a bright display with plenty of contrast, perfectly readable from afar, and perfectly silent.