Designing or using a clock directly?

[lowkb]

Hi all,

This is great. found this intresting place whilt trying to find my solution. Maybe can get some help from you guys who share the same interests.

Ok, my problem here is that i need a real low clock supply: an 8KHz clock supply. My circuit dun use a microcontroller, so i need to find ways to supply my frequency source. But after search, i noticed the lowest available clock crystal is in Mhz. disappointed.

I'm trying not to use a resonator cause my 8kHz clock is for ADC and i dun wish to see it gets messy. Any guys can think of a good and clean way to get this 8Khz???

Thanks...

 

[Someone Electro]

If it dosent need to be acurate just use an 555 timer.

 

[lowkb]

hi,

i thought of that too... i want it good, thats y im not using resonators.

Tough choice to get one rite?

 

[Someone Electro]

you cod try to serach the web for some oscilator ICs

 

[Styx]

schmitt inverter with resitor in the feedback feeding a capacitor to ground.

You can get really low freq this way

 

[Roff]

Mouser has a 32kHz quartz crystal. Build an oscillator with it and divide the output by four.
Here is an example of an **broken link removed**. You can find others (most will be similar) by searching with Google.

 

[audioguru]

Unfortunately a CD4060 or CD4541 oscillator/counter don't have a divide by 4 output for Ron's circuit. Pin 7 of a CD4040 is the 32kHz clock of Ron's circuit divided by 4 for a very accurate 8kHz.

 

[john1]

Hi Lowkb,

Ron is right. I never thought of watches.
A 32 k/c crystal is about the best you will do
without spending a lot on some special item.

Getting 8 k/c from it will not be difficult.
I see Audioguru has it covered.

At those low frequencies you should take special care
with the rise times, dunno if the fall times matter so much,
and of course the interval of the pulse has to be short.
Maybe very short.
Depends what you're clocking with it.

Maybe some hand built digital converter .... ?

Best of luck with it, John

 

[Nigel Goodwin]

I see no reason for the ADC clock to need to be particularly accurate?, I suspect a 555 or CMOS gate oscillator would be more than accurate enough for the job.

 

[lowkb]

Cool...

Got so many reply. Thank you all so much for the alternative. I will consider the 2 suggestions mentioned carefully and build it to see the results.

Thanks again.

Regards,
Andy