This is a simple ESP32-C3 based clock with the special feature that the display is made of match stick sized Led filaments in a seven segment configuration with colon separators. These are similar to the ones found in some mains Led light bulbs but are lower voltage and can be obtained in Ebay/Aliexpress and other stores.
The time is maintained from an internet time service and each seven segment display is driven directly from its own shift register (non-multiplexed) also with brightness control. The design is modular and the full clock is made of three interconnected circuit boards. One is the control board also with the two “hours” digits. There are also two identical boards for minutes and seconds with preceding colon separators. The “seconds” board is optional and can be omitted if not required.
The representation in the photograph is doesn’t quite do it justice, possibly because of the PWM brightness control is confusing the camera. Anyway, it looks much better and brighter in real life.
All schematics, code and a full description are supplied in case any one wants to duplicate the project or just see what I did. I hope someone finds it useful or interesting.
Led Filament Clock Description.pdf (939.0 KB)
Led_Filament_clock_control_v0_01.pdf (201.8 KB)
Led_Filament_clock_display_v0_01.pdf (163.6 KB)
led_filament_display_V1_01P.ino (9.1 KB)
EDIT
Here are the Gerber files for both board types I used. The whole Kicad project is too big to publish here otherwise I'd have included that.
Control and "Hours" digits.
FC_C_Gerbers.zip (140.3 KB)
"Minutes" board ("seconds" board is identical)
FC_D_gerbers.zip (113.4 KB)
Notes for using the Gerbers:
The power jack and the fuse holder are optional if you use the specified leds and series resistors.
Some ESP32-C3 Supermini boards have appeared in the meantime with some different pinouts.
The Gerbers match JLCPCB design rules but I think that these are quite standard.