[Lewis] has just the thing for that: a big expandable 7-segment display. The build is modular, allowing it to be extended from 2 to 10 digits and beyond. The digits themselves are made of 3D ...

To turn on a segment, he connects a segment to a GPIO pin set high while sending 3.5 volts out of the DAC output into the display’s common connection. The difference between the two pins is 1.5 ...