# Frequency divider (cyclic)

Discussion in 'The Projects Forum' started by Tester71, Nov 12, 2014.

1. ### Tester71 Thread Starter New Member

Oct 29, 2014
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0
Hello, I have a circuit that uses a frequency divider with a 4017 IC. I can connect the reset to diferent outputs to get differente dividers with a circular switch, to get lower frequencies of the clock freq.

I was wondering how can I make it happen automatically, continuosly.....for exemple....another 4017 counter that triggers some “switches” to change the RESET position of the first 4017 IC. I would like to change the freq divider continuosly between certain values, and without relays....

Thank you!

2. ### alfacliff Well-Known Member

Dec 13, 2013
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428
use a multiplexer chip to switch and a counter to address the multiplexer.

3. ### Tester71 Thread Starter New Member

Oct 29, 2014
26
0
Thank you alfacliff. For example? what multiplexer chip would you use? Vcc = 12v, or 5v if needed.
Thanks again.

4. ### Tester71 Thread Starter New Member

Oct 29, 2014
26
0
Any example of multiplexer chip?.
Tks.

5. ### wayneh Expert

Sep 9, 2010
12,405
3,256
Just trying to understand what you want to do. To clarify, the changing of the reset counter does NOT depend on the output of the frequency counter, but instead flips back and forth between two preset values, say, 7 and 9? Does the frequency of that flipping need to be related to the clock applied to the 4017, or could it be a simple tick tock between the two values?

6. ### Tester71 Thread Starter New Member

Oct 29, 2014
26
0
Hello wayneh....It could be a simple tick tock independently that changes the reset position. I would like to change between five or six reset positions to obtain different ratios of the clock signal.
Sorry for my written English.

7. ### wayneh Expert

Sep 9, 2010
12,405
3,256
Then I think alfacliff nailed it. The outputs of the 4017 must be multiplexed so that, at the right moment, one of those outputs gets selected and routed to the reset pin.

8. ### Tester71 Thread Starter New Member

Oct 29, 2014
26
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Ok, and do you have some IC examples I could use for multiplex and counter to manage the multiplexer?

9. ### wayneh Expert

Sep 9, 2010
12,405
3,256
I've never used one, so I don't have a favorite. Search these forums for "multiplexer" and you'll find some recommendations. Or start a thread titled "Need multiplexer recommendation". That's the right bait to catch the big fish.

10. ### Tester71 Thread Starter New Member

Oct 29, 2014
26
0
THANK YOU very much. I will do it ASAP