Electromechanical four-digit seven-segment clock shows the time silently
March twenty eighth, 2022—
Whereas digital show applied sciences exist for almost each doable use case, typically you need the aesthetics that solely electromechanical shows present. Many manufacturers have constructed electromechanical seven-segment shows for this function, however they’re often pushed by noisy servo motors. David McDaid needed one thing quieter and created this silent electromechanical four-digit seven-segment show to be used as a wall clock.
Like most related shows, this makes use of a person motor for every phase of every digit. For 4 digits, that may be a whole of 28 motors. 28 servo motors get fairly noisy, which is why McDaid employed stepper motors paired with silent drivers. These are sometimes used for 3D printers with a view to make these printers much less annoying, however they work nicely for this venture, too. These stepper motors solely have to tilt their respective segments by 90 levels to “flip off” that phase, so little torque was required.
McDaid carried out frequent 12V 28BYJ-48 steppers with BIGTREETECH TMC2208-V3.0 drivers. As a result of there are such a lot of motors to drive, McDaid selected an Arduino Mega 2560 for management. It sends UART indicators to the drivers by means of a collection of chained shift registers on customized PCBs, so every set of seven segments undergo a single PCB. A DS3231 RTC module retains time. 5 enter buttons let McDaid set the time or swap between modes — together with a mode that shows a random 4 letter phrase. McDaid 3D-printed the segments in a pleasing gold shade, which contrasts nicely with the gray-painted again board.