Digital 7 Segment Pulse Counter
A pulse counter can be built by using 7490 decode counter and 7557A. This circuit can count from zero to 9. Pins 3 and 2 of all 7490’s must be connected together. Here is the schematic diagram of the circuit:
A push button is used as reset. The input of this circuit is a pulse that is produced by other device. This circuit uses seven 330 ohm resistors that can be found in a single package. If want to count up to 999, we can cascade this circuit up three stage.