A very useful 3-digit counter built around MC14553 & CD4543 CMOS ICs. It counts from 0 ~ 999 . Two or more units can be cascaded to form a 6, 9 ... (or any multiple of 3) digit counter..
When the count exceeds 999, the display rolls over to 0 & the overflow output goes high briefly. (please refer to datasheets for details on overflow)
Inputs : master reset, clock, latch enable Outputs : Overflow
Click here for datasheets HEF/CD 4543 / MC!4553
Free red filter for LED displays (~ 3x6 cm)