This project is about to use four CD4543 "BCD-to-Seven-Segment" drivers to drive four 7-Segment elements; the drivers
are driven by an Arduino Micro (any microcontroller board with enough I/O pins can be used for this).
The Arduino source code, images of my prototype, a socket (to hold the assembled board; STL for 3D printing) and the circuit (as PDF) can be downloaded here.



Parts list:

Count	Item	Value	Description
4	R1 - R4	180Ω	Resistor for 7S's
1	R5	68Ω	Resistor for LED's.
2	S1 - S2	Push buttons	To adjust hours and minutes
4	DIS1 - DIS4	CD4543B	Driver
1	C1	220μF; > 5V	Capacitor for stable power source
4	C2 - C5	440μF; > 5V	Optional "Fear capacitor"
1		Stripboard	Optional
1		Arduino Micro	Microcontroller
2	LED1 - LED2	LED	LED's between hh and mm

Note that in the schematic the power circuits of IC1 - IC4 are next to the IC's, altough they are integrated in the IC's itself:



The brightness of the 7S's can be adjusted with the resistors R1 to R4, the brightness of the center LED's can be adjusted with R5 (increase value = brightness down).
To get a stable voltage, i placed the capacitors C1 to C5 between GND and the specific VSS pins, maybe they can be left out, but i recommend them.



Since i wanted to use my clock (which is difficult, if the board is in a horizontal position), i printed a "board holder":



Feel free to create your own clock based on this, and don't hesitate to contact me if you running into any problems!