1hz clock

But which would should I use? There are three on that page.

My counter chip is a 74393, i will be running the power supply at 3V (2x AA) and I will be using this crystal.

Whoops. Then how about 3x AA, which would be 4.5V?

Whops again.... I meant to say 74HC393. :( Sorry for the confusion!

Try the simplest one first baum, if that works then you're all set. If not, try another.

So the second one w/ 3 inverters and a 100N cap?

I would have suggested Figure 3 from this link first http://www.eetkorea.com/ARTICLES/2001SEP/2001SEP06_AMD_AN.PDF 1 inverter, couple of 22pF caps, couple of resistors.

But where do I get my frequency output from? I would prefer that one, though.

Thanks a lot! baum

OK. and they mention a range for Rf, but for R1 they say it = XC1. What does this mean? Is it the frequency times C1 (which would be 22pf for me)? In that case R1=65,536*2.2E-11= 1.441792x10^-6?!!!!

Help!

I see you attached a picture of some oscillators, but these only come in frequencies higher than 1Mhz... I'll try these suggestions when the parts come.

Thanks! baum

But I would need a power of 2 for it to work out. Digikey doesn't have any powers of two oscillators (2^20, 2^21, 2^22, etc.).

Excellent! THANK YOU SO MUCH!!!!! But I can use 4.5V (3x AA) still, right?

Also, the crystal datasheet says 12.5pF load capacitance. Should I change that, or leave it how you have it?

Thanks again! baum

p.s. you are right about digikey, but they generally tend to be the best and easiest for finding obscure components that I can't get at sparkfun or another similar store.

But what about the 100pF cap?

BTW: I found that circuit simply by Googling for: 1Hz crystal oscillator

I should be sent back to 1st grade for forgetting that. Idiot.

Can I just use the formulas form one of the documents CrossRoads posted?

underestimating linear circuit design.

What do you mean?

and I will try those formulas some time...

Are there any other easier ways of getting a 1Hz square wave with 50% duty cycle?

You win. I'll just get the cheapest RTC they have... but I will feel a little cheated, using the sq wave of an RTC to power a clock... :(

Thanks for all the help, everyone. I'll try the oscillators that will oscillate some other time....

Just a simple idea.. But dont know if it works for you.. U can take a clock cob board from a clock or alarm.. And loop out the coil connections.. And that will give u a 1hz clock. I have used the same with peojects which needed 1hz clock.. U cant get any simpler than that.!!! Or just in 2 dollars... U cant go further cheep!

Showlyshah: Just a simple idea.. But dont know if it works for you.. U can take a clock cob board from a clock or alarm.. And loop out the coil connections.. And that will give u a 1hz clock. I have used the same with peojects which needed 1hz clock.. U cant get any simpler than that.!!! Or just in 2 dollars... U cant go further cheep!

Actually, you almost can. RTC modules are down to about US\$2 with free shipping now.

There used to be a chip for this... now its basically unobtanium.

EBAY