Paco Cañada created a faboulous Function Decoder with a minimum amount of components, based on the 12F629 Pic microprocessor.
I changed the package of some components and created a small PCB (with SMD components), 18.5mm * 12mm.
When using the PCB Gerber files, one PCB contains 35 decoders.
The PCB can be soldered by hand (load the firmware in the microprocessor first!), although a magnifier would become helpful.
All files (including a copy of Paco’s manual and firmware) can be found here.
Note that a ‘via’ is missing in the bottom-left decoder. A small wire will solve that problem.