event counter - with LED indication

rim with LED indication An event counter, as could be ex- pected, counts events, or, to be more precise, it counts the occur- rences of a particular event. The counter here may seem a bit limited, as it can only go to 99, but in fact it can be expanded almost infinitely. The read-out consists of two lines of LEDs, one for units and the other for decades. Only one LED per line (at most) will light at a time so the cur- rent consumption is quite low, cer- tainly when compared to a set-up with 7-segment displays. The actual counter consists of two 4017 decade counters. When the reset button is pressed both QO out- puts go high. Every clock pulse arriv- ing at pin 14 of IC1 makes the next output of the IC go high. At every tenth clock pulse the CO output goes high and clocks IC2 and at the same time IC1 is reset to 0. After 99 pulses both IC1 and IC2 reset to zero and the sequence starts again. In principle the carry output of IC2 can be used to extend the circuit infinitely. The outp...