After assembling #Ternary clock I realised that by using bicolour LEDs I could combine 2 LEDs in one lamp so that each one could display a trit (ternary digit). I ordered some red-green bicolour LEDs, and designed and had the circuit fabricated.

You can see from the date on the schematic that this was done a couple of years ago. I encountered problems getting the board to work, all due to poor soldering. Today I decided to tackle the dodgy board and went over all the joints again. I very quickly got the lower shift register and LEDs working, but the upper LEDs remained dark. Another round found a faulty daisy chain connection. After that the test Arduino sketch worked perfectly. The "font" table is still binary, as each LED requires two lines plus common anode.

On the physical board, I've only installed 7 LED pairs. The lower 4 can display 0-80, enough for a minutes display. The upper 3 can display 0-26, enough for a 24-hour display. So 7 LED lamps can display the time. I haven't inflicted such a clock on any of my friends yet. I have to wait. They are still staying clear of me after I inflicted conventional clocks on them. 🤣