|The 7490 integrated
circuit counts the number of pulses arriving at its input.
The number of pulses counted (up to 9) appears in binary form on four pins of the ic.
When the tenth pulse arrives at the input, the binary output is reset to zero (0000) and a single pulse appears at another output pin.
So for ten pulses
in there is one pulse out of this pin.
If this pulse
is applied to the input of a second 7490 then this second ic will count
the pulses from the first ic.
The 7490 can
be connected to divide by other values.
Copyright Graham Knott 1999