Why 32.768 khz

Essentials Only Full Version. Super Member. Why I had been using And I wonder why this particular value? If we connected the XTAL to a counter with output in binary D15 to D0, then we simply have to monitor the pin D15 and when that pin goes high, we have 1Sec complete. If we use micro controller for RTC function, then it really does not matter if we have a Thats because, we will anyway compare the entire number and not just 1 bit.

Is it something to do with manufacturing constraint? RE: Why Indeed, this is my understanding. I believe a lot of RTC chips rely on that exact division to stop errors creeping in. As to the speed. Generally, it is taken that the faster something oscillates, the more accurate it is. New Member. It's mostly because Economies of scale dictate that they will always be cheap - a few pence in most cases. So finally, it boils down to what is cheaper and practical to use. Do you have any idea what metal the tuning fork is coated with along its surface?

I found what you have written interesting. I have a very large laboratory grown quartz crystal. I also have a signal generator with about 10 frequency ranges. I would like to determine the natural frequency of the crystal and see if it would emit light when excited at that frequency?

Your email address will not be published. Output Frequency of Precise Frequencies for the Mass Market Several decades passed before the quartz watch finally found its way into the mass market. Tagged under: November at Pascal Simon says :. Hi Mr. Tor Schofield says :. Tor Schofiekd says :. December at I once heard somewhere that a specific natural occuring shape of crystal would oscillate at exactly Don't know if this holds any truth though.

Well, I think the answer is that even the Hz is a pretty delicate and susceptible crystal as it is. As it is, for maximum stability the Hz crystals need special guard planes and such to keep out EMI.

Clock crystals are usually artificially grown and cut in a tuning fork shape. Tuning forks give pretty pure signals with less dominant overtones near the fundamental frequency. I think their 2nd overtone is about 6 times f o. This makes it easy to filter out without diminishing the fundamental too much. The Hz frequency was chosen many years ago, in the early days of digital watches. The need was for a crystal that was small and tough enough to use in a watch, but the IC used to divide it down to 1 second pulses had to draw very little current.

So the frequency chosen was a power of 2 to keep the divider IC as simple as possible, and Hz was a good compromise.