After I created an improved version of my proof-of-concept 6-segment display for my #6 segments suffice project, I had a pile of obsoleted PCBs. What to do with them? I realised I could fit them with white LEDs and use them as a bench lights. Two digits have 12 segments or 48 LEDs. I used an 8048 board of which I have many unused units to be the PWM controller. It's underkill as the firmware is only a couple of hundred bytes whereas those MCUs could do more (they used to be in 5¼ inch floppy controllers), but also overkill as a simple modern MCU driving a MOSFET switch could do the job. 😉 It was fastest to use what was on hand, and the software was easy to write.

The voltage required by 4 white LEDs in series is greater than the 5V from a SMPS wall wart, so I have finally made use of the space reserved on the 8048 board for an adjustable boost converter to provide 14V for the LEDs. There is no multiplexing; we run the LEDs at 10 mA max for a total draw of 120 mA @ 14V.