Digital Quartz Clock Built Using Logic ICs and 7-Segment Displays
Makers and engineers have designed all sorts of projects using logic ICs, including computers, smoke detectors, security alarms, and more.
Erik van Zijst took a handful of them, along with several 7-segment displays, to create his digital quartz clock, which even dims when the sun goes down. What’s more, the clock doesn’t use any code to display the time.
van Zijst's digital quartz clock features an assortment of Electronics-Salon’s 74HCxx series logic ICs, which he used to drive six 7-segment LED displays via BCD (Binary Coded Decimal) counters to produce the numbers 0 to 9 for minutes and hours.
The time is manually set using three buttons, in the same fashion as those digital clock radios from the ’80s and ’90s.
The digital timepiece makes use of a 555 IC and photoresistor for automatic brightness control, which adjusts the displays depending on the amount of ambient light via PWM. van Zijst initially used a breadboard to prototype his clock, and after fleshing out his design, he leveraged KiCAD to create a custom PCB, populated by the neatly arranged electronics.
As with any project, there are bound to be unexpected problems, and van Zijst found an issue with the clock’s crystal oscillator circuit that didn’t function correctly and was replaced with a MEMS-based oscillator IC.
After everything was found to be in working order, he then 3D-printed a mounting plate, which is employed to anchor the clock to the wall. van Zijst provides a detailed walkthrough of his homemade clock on his website or those interested, which includes links to his schematics and design files.