audioguru2
- Apr 6, 2004
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- Apr 6, 2004
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Quartz crystals and ceramic resonators operate at high frequencies. You make a high frequency oscillator with one then use a counter IC to divide the frequency down to 100Hz.
A CD4060 IC is an oscillator with a counter that can divide up to 16,384.
A CD4060 IC is an oscillator with a counter that can divide up to 16,384.
Ldanielrosa1
- Nov 25, 2003
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- Nov 25, 2003
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Well jcbarber, you have an almost limitless variety to choose from. You can expect better accuracy from crystals than ceramic resonators, the flip side being that resonators are usually cheaper- but for one-off projects that won't matter much.
You said you wanted to use 100Hz for your master clock signal- I will assume that you will be multiplexing the display at this rate, among other things. So it is of primary importance that your crystal frequency divide by this.
Beyond that, binary ripple counters are easy to find and simple to implement- minimal circuit complications. So look for frequencies that have binary values and end with "00", like 1,638,400. A lot of these you will not find, but you may find 1,024,000- the key difference being the number of zeroes. So you may find that you need one stage of decimal division. Another option is choosing another frequency for your master clock, that way you can use ripple counters for everything else and have the wierd number worked out in the last few stages.
Good luck.
You said you wanted to use 100Hz for your master clock signal- I will assume that you will be multiplexing the display at this rate, among other things. So it is of primary importance that your crystal frequency divide by this.
Beyond that, binary ripple counters are easy to find and simple to implement- minimal circuit complications. So look for frequencies that have binary values and end with "00", like 1,638,400. A lot of these you will not find, but you may find 1,024,000- the key difference being the number of zeroes. So you may find that you need one stage of decimal division. Another option is choosing another frequency for your master clock, that way you can use ripple counters for everything else and have the wierd number worked out in the last few stages.
Good luck.
Ldanielrosa,
Thanks for the info. I guess I should describe my project a bit more. I'm using a basic stamp 1 that only does integer math and is very limited in memory, so I need my hardware to do the work. My base unit for the decimal or base ten clock will be 1/100000 of a day which is 8.64 seconds. With the 100Hz resonator I can count 864 cycles and have my 1/10000 of a day. The display will either be an LCD or 7 segment LEDs and look like 5.000 for noon (0.000 for midnight). I guess the equation to figure on the ripple counter is frequency wanted = frequency of the resonator/2n I guess 2n is determined by which pin on the ripple counter you use as an output (which I still need to figure out). Thanks again!
JCBarber
Thanks for the info. I guess I should describe my project a bit more. I'm using a basic stamp 1 that only does integer math and is very limited in memory, so I need my hardware to do the work. My base unit for the decimal or base ten clock will be 1/100000 of a day which is 8.64 seconds. With the 100Hz resonator I can count 864 cycles and have my 1/10000 of a day. The display will either be an LCD or 7 segment LEDs and look like 5.000 for noon (0.000 for midnight). I guess the equation to figure on the ripple counter is frequency wanted = frequency of the resonator/2n I guess 2n is determined by which pin on the ripple counter you use as an output (which I still need to figure out). Thanks again!
JCBarber
Ldanielrosa1
- Nov 25, 2003
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Ah, I see. I have no experience with the BS series. I did just look at some of the literature though.
I have not determined whether or not you can access TMR1, but even if you can the BS1 uses a ceramic resonator so the frequency will wander. Alas, the external hardware is necessary.
Just the same, it'll be an interesting clock- a decimal day.
I have not determined whether or not you can access TMR1, but even if you can the BS1 uses a ceramic resonator so the frequency will wander. Alas, the external hardware is necessary.
Just the same, it'll be an interesting clock- a decimal day.
Yeah it is very limited. I thought about a divide by 10 circuit with a 1 MHz crystal but it would take 4. A standard clock crystal only allows me down to a 100th of a day (not small enough more than 15 min) because of the stamp, too bad there isn't a divide by 100 circuit. Well thaks so much for all your help and ideas
JCB
JCB
