Designing or using a clock directly? - Electronic Circuits Projects Diagrams Free

lowkb · 30th July 2005, 12:09 PM

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 · 30th July 2005, 12:12 PM

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

lowkb · 30th July 2005, 12:15 PM

hi,

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

Tough choice to get one rite?

Someone Electro · 30th July 2005, 12:31 PM

you cod try to serach the web for some oscilator ICs

Styx · 30th July 2005, 12:49 PM

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

You can get really low freq this way

Roff · 30th July 2005, 03:12 PM

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

audioguru · 30th July 2005, 04:06 PM

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 · 30th July 2005, 05:09 PM

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** · 30th July 2005, 07:12 PM

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 · 31st July 2005, 03:11 AM

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

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30th July 2005, 12:09 PM	#1
lowkb	Designing or using a clock directly? 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... __________________ ********************************** Hello All..... **********************************

30th July 2005, 12:12 PM	#2
Someone Electro	If it dosent need to be acurate just use an 555 timer. __________________ Il give you shocking experience.

30th July 2005, 12:15 PM	#3
lowkb	hi, i thought of that too... i want it good, thats y im not using resonators. Tough choice to get one rite? __________________ ********************************** Hello All..... **********************************

30th July 2005, 12:31 PM	#4
Someone Electro	you cod try to serach the web for some oscilator ICs __________________ Il give you shocking experience.

30th July 2005, 12:49 PM	#5
Styx	schmitt inverter with resitor in the feedback feeding a capacitor to ground. You can get really low freq this way __________________ Nothing is impossible. Once a problem is realised, the rest is just details

30th July 2005, 03:12 PM	#6
Roff	Mouser has a 32kHz quartz crystal. Build an oscillator with it and divide the output by four. Here is an example of an oscillator circuit. You can find others (most will be similar) by searching with Google. __________________ Ron

30th July 2005, 04:06 PM	#7
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. __________________ Uncle $crooge

30th July 2005, 05:09 PM	#8
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

30th July 2005, 07:12 PM	#9
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. __________________ PIC programmer software, and PIC Tutorials at: http://www.winpicprog.co.uk

31st July 2005, 03:11 AM	#10
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 __________________ ********************************** Hello All..... **********************************