how to work with CD4060B to change the timing

[srevish]

Dear All,

I am quite new to work with ripple binary counter.

I have attached the circuit diagram of my project, this counter has the cycle time of 10 mins. I want to reduce the timing to 6 mins.

Please help me to solve this problem.

 

[betwixt]

The only practical way to speed it up is to change the crystal frequency. To go from 10 mins to 6 mins you need 52.946KHz based on the frequency you are already using but the 31.768KHz on your schematic is unusual, are you sure it isn't 32.678KHz which is a standard value? If it is 32.768KHz, the new crystal should be 54.613KHZ.

Brian.

 

[BradtheRad]

You are tapping from the highest bit (pin Q14). It looks as though you are resetting it from another IC. Or is On for 10 minutes, then Off for 10 minutes?

Anyway, suppose you were to tap from Q13. Its cycle will be half the length. 5 minutes.

And then suppose you were to find another pin or pins, which, combined with Q13, all go high at the 6 min. mark.

Send those outputs to an 'AND' gate.

You'll then need to set the ripple counter to zero.

 

[srevish]

The only practical way to speed it up is to change the crystal frequency. To go from 10 mins to 6 mins you need 52.946KHz based on the frequency you are already using but the 31.768KHz on your schematic is unusual, are you sure it isn't 32.678KHz which is a standard value? If it is 32.768KHz, the new crystal should be 54.613KHZ.

Brian.

Dear Sir,

Thank you very much for your reply.

Can you please tell on which calculation bases 54.613KHz is choosed and how it is converted to 6 mins ?

 

[crutschow]

The only practical way to speed it up is to change the crystal frequency. To go from 10 mins to 6 mins you need 52.946KHz based on the frequency you are already using but the 31.768KHz on your schematic is unusual, are you sure it isn't 32.678KHz which is a standard value? If it is 32.768KHz, the new crystal should be 54.613KHZ.

31.768KHz is a standard watch crystal frequency. A 15-stage divider of that frequency gives a 1Hz output.

 

[betwixt]

2^15 in my calculations is 32768 not 31768 !

Srevish, I used a simple calculation you want to speed up 10 to 6 so the increase is by 10/6 times. The crystal therefore has to be 10/6 times the original frequency.

Brian.

 

[crutschow]

2^15 in my calculations is 32768 not 31768 !

.................

Yes, that's a typo, it's 32768. I believe you made one also when you gave the value as 32.678 kHz. ;-)

 

[betwixt]

darn, ya got me!

Brian.

 

[srevish]

2^15 in my calculations is 32768 not 31768 !

Srevish, I used a simple calculation you want to speed up 10 to 6 so the increase is by 10/6 times. The crystal therefore has to be 10/6 times the original frequency.

Brian.

Dear Brain,

Thank you very much for your reply.

As per the datasheet of CD4060B, I refereed it as 14 stage ripple carry binary counter. so does it says 2^14 ? . By using 2^14 with 32.768KHz i am getting 0.5 Sec.

I am able to understand that 54.613KHz will increase my clock speed, but is that 54.613KHz standard available cry oscillator ? . If this crystal is not available then is there is any other way to increase the speed ?

 

[betwixt]

Without knowing what the second IC in the schematic is and the contents of the EPROM it's difficult to know how many cycles are divided before the 4060 is reset. Normally, dividing 32768 by 2^14 would give you 2Hz output rather than 0.5HZ.

All the timing comes from the 4060 oscillator so any circuit that produced your new frequency should work. If it doesnt have to be precise timing you could use a simple RC oscillator or even a 555 timer but if you need the same degree of accuracy, the only option is a different crystal. You could generate the 54.613KHz by some other method and inject it into the existing circuit instead of using the crystal if it's easier that way.

I would not advise you to use a different output on the 4060 and lower the crystal frequency unless you know the contents of the EPROM and are sure it will still manage to access all it's addresses. In any case, lower frequency crystals would be harder to source then higher frequency ones.

Brian.

 

[srevish]

Without knowing what the second IC in the schematic is and the contents of the EPROM it's difficult to know how many cycles are divided before the 4060 is reset. Normally, dividing 32768 by 2^14 would give you 2Hz output rather than 0.5HZ.

All the timing comes from the 4060 oscillator so any circuit that produced your new frequency should work. If it doesnt have to be precise timing you could use a simple RC oscillator or even a 555 timer but if you need the same degree of accuracy, the only option is a different crystal. You could generate the 54.613KHz by some other method and inject it into the existing circuit instead of using the crystal if it's easier that way.

I would not advise you to use a different output on the 4060 and lower the crystal frequency unless you know the contents of the EPROM and are sure it will still manage to access all it's addresses. In any case, lower frequency crystals would be harder to source then higher frequency ones.

Brian.

Dear Brain,

Thank you very much for your reply, your idea is very helpful for me.

I will update the results to you after changing the frequency.