His clever solution is to use an Arduino Uno R4 and take advantage of the onboard DAC. To turn on a segment, he connects a segment to a GPIO pin set high while sending 3.5 volts out of the DAC ...

For the simplest of builds, 7-segment display modules usually get ... The rest of the build is pretty plain vanilla — an Arduino Nano clone, a DS3231 RTC, a Lithium battery, and some buttons ...