1HZ Clock From A 10Mhz Oscillator Module

Thread Starter

maker_2023

Joined Nov 20, 2023
167
Hi:
I want to obtain a 1Hz Clock From A 10Mhz Oscillator Module. I would like to use
CD4000 series CMOS since I have a good supply of these. I can't really determine
which chip(s) to build the frequency divider chain with. Could someone please advise?

Thanks,
M
 
Last edited:

Papabravo

Joined Feb 24, 2006
21,225
You would have to start your divider chain with some part that are not from the CD4000 series. I would recommend the 74LVC1G to do at least a dive by 8. That will get you to 1.25 MHz. which should be within the capacity CD4000 series CMOS parts with a 5V supply. You still have a problem with the divisors from there because 1.25 MHz is not a multiple of so you are going to have to find the prime factors of 1.25E+06 and proceed from there to get exactly 1 Hz.

\( 1,250,000\;=\;2^4\cdot5^7 \)

You're going to need some divide by 5 stages to go with the divide by 2 stages. Good luck with that one.
 

schmitt trigger

Joined Jul 12, 2010
901
Start with an 74HCT390, dual high speed CMOS with TTL-threshold for the first stage. It will divide down to 100Khz, which should be sufficient for standard CMOS at 5 V.
It is very important that you procure the H C T variant. All the 10Mhz sources I am aware of, will output a 3V waveform, which is not sufficient to reliably clock a CMOS-threshold counter.
 

Thread Starter

maker_2023

Joined Nov 20, 2023
167
Start with an 74HCT390, dual high speed CMOS with TTL-threshold for the first stage. It will divide down to 100Khz, which should be sufficient for standard CMOS at 5 V.
It is very important that you procure the H C T variant. All the 10Mhz sources I am aware of, will output a 3V waveform, which is not sufficient to reliably clock a CMOS-threshold counter.
Thanks!
 

AnalogKid

Joined Aug 1, 2013
11,052
The problem with a 32 kHz crystal is that there is no way to get a 1 Hz signal without using two chips. Do you have a CD4521? This, plus a higher freq crystal, gets you 1 Hz in 1 chip.

If not, then still consider a higher freq crystal than 32 kHz. A 32.768 kHz crystal is not a true crystal. It actually is a tuning fork, and is less accurate and less stable than a real crystal, especially over wider temperature ranges. A CD4060 (oscillator plus divider) plus any of the other multi-bit dividers (CD4020, 4024, 4040, etc.) lets you use a 1.048 MHz or 2.097 MHz true crystal for better accuracy and stability.

ak
 

sarahMCML

Joined May 11, 2019
370
The problem with a 32 kHz crystal is that there is no way to get a 1 Hz signal without using two chips. Do you have a CD4521? This, plus a higher freq crystal, gets you 1 Hz in 1 chip.

If not, then still consider a higher freq crystal than 32 kHz. A 32.768 kHz crystal is not a true crystal. It actually is a tuning fork, and is less accurate and less stable than a real crystal, especially over wider temperature ranges. A CD4060 (oscillator plus divider) plus any of the other multi-bit dividers (CD4020, 4024, 4040, etc.) lets you use a 1.048 MHz or 2.097 MHz true crystal for better accuracy and stability.

ak
There is actually. I got a CD4536B Programmable Timer chip to give a 1Hz output recently using pins 3 and 5 in the standard CD4060 type oscillator circuit, although it needed slight changes to the resistor values (a 1M feedback and a 330k in series with the Xtal), and it ran quite happily, but needing about 4.5V minimum to start reliably!
 

Thread Starter

maker_2023

Joined Nov 20, 2023
167
There is actually. I got a CD4536B Programmable Timer chip to give a 1Hz output recently using pins 3 and 5 in the standard CD4060 type oscillator circuit, although it needed slight changes to the resistor values (a 1M feedback and a 330k in series with the Xtal), and it ran quite happily, but needing about 4.5V minimum to start reliably!
I don't have a CD4536B or a CD4521 but I can order them once I have a large enough order.
I was actually trying to get a datasheet for the CD4536B but Digikey doesn't have it on their site.
 
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