Question about Frequency Counters

[Space Varmint]

OK, I'm using a 32KHz crystal in a 74hc4060. Currently I am using one of the dived by 2 outputs to get a 1KHz gate pule as the input to an AND gate along with the input frequency to be measured. So, works fine at 1KHz resolution but I would like to take it on down to 1Hz resolution. So I need a 1Hz gate signal. I want to use the same 32KHz crystal and the '4060 oscillator/13 stage binary counter. I am using 74hc390 decade counters and have a few more on hand. The problem is the QD outputs are not 50% duty cycle. So here is the question:

Could I use a 2KHz output from the '4060 and divide it down through 3 stages of decade counters to get 2Hz, then use the 2Hz to drive a J-K flip flop setup up for toggle mode to get a stable 1Hz with 50% duty cycle?

 

[kchriste]

then use the 2Hz to drive a J-K flip flop setup up for toggle mode to get a stable 1Hz with 50% duty cycle?

Yes, that would work fine. Or switch the counters around so that the last one is a divide by "power of 2".

 

[Space Varmint]

Alright kchriste! Yeah, I see it now. I don't really have enough room on this Radio Shack perf. board which I already cut in half. So I added one J-K flip flop and dropped the resolution down to 100Hz which should be OK for my customer. But it also proved out my theory.

 

[Mikebits]

The problem is the QD outputs are not 50% duty cycle.

In digital, duty cycle should be of no concern as you only care about periodicity and the rising edge or invert for falling edge.

-------------edit---------------
Why are the QD outputs not 50%. It is a digital part. I think I am confused.

 

[Space Varmint]

Hey Mike! Yeah, look at the output signals sometimes on a decade counter. They aren't 50%. I forget what the internals are but it is a combination of I think divide by 2 and divide by 3 to come up with divide by 10. So on the sample "gate" pulse you do need 50% duty cycle because you are running that through an AND gate and the incoming signal comes through the other input. The frequency is like half the sample frequency. So if you want to read to 1KHz resolution you will use 500Hz because each half of the cycle will be at twice the frequency or 1KHz. So you gate in one full KHz of frequency and then count the pulses.