I designed this board to demonstrate how to use the CD4026. It can greatly reduce the number of GPIO required to operate a 7-segment display, or remove the need for a microcontroller altogether!
The learning board has 3 different demonstrations of how to generate the required clock signal for the CD4026. The first is a button, where each press will increment the counter by 1. The second is a 555 timer, that will count at a frequency determined by the 100k potentiometer. The third is a photoresistor counter, that will determine when someone passes by and breaks a laser beam.