How do I make a Divide-by-3 counter??

Question

Please tell me how I can make a divide-by-3 counter using 74LS90 IC's?

Answer 1

Take the output of Q0 and Q1 and connect them to MR1 and MR2.
This way when both the 0 and 1 bit are 1 (i.e. after three cycles) the counter will reset itself.
Q1 will be your output.

The sequence Q0 and Q1 will go through is:
Q0 = 0, Q1 = 0

(clock tick)
Q0 = 1 Q1 = 0

(clock tick)
Q0 = 0 Q1 = 1

(clock tick)
(momentarily) Q0 = 1 Q1 = 1
(and then, *way* before the next tick)
Q0 = 0 Q1 = 0
(we're back on the first step, after three ticks have passed - success!)

Answer 2

following this diagram:
http://eshop.engineering.uiowa.edu/NI/pdfs/00/63/DS006381.pdf

we see that pin 9 (Qb) goes high on count 2 (which is the third count.)

If we apply the output of pin 9 to pin 2 and 3 (Ro1 and Ro2) we reset the counter to zero.

Answer 3

Not formula with that one but normally u just pumper the output to reset the counter.

Answer 4

try this website http://forum.allaboutcircuits.com/