Crystal oscillation at 2 to the 15th power...

anyone (EEs?) know why this number was chosen and used in clocks and watches way back in the late 1800s and early 1900s and then carried over to processor controllers and worked so well for them? i know i didn't ask this quite right...

in other words, why do RTCs use 32.768Khz? What is the significance of 2^15 ticks/second?

ideas? clues?

[edit on 13-6-2008 by ~Lucidity]

[edit on 13-6-2008 by ~Lucidity]

Originally posted by ~Lucidity
in other words, why do RTCs use 32.768Khz? What is the significance of 2^15 ticks/second?
ideas? clues?

32.768Khz is used as a binary number. This allows binary division, for binary code.

en.wikipedia.org...

0.032768 Real-time clocks, allows binary division to 1 Hz signal (2^15 × 1 Hz); also often used in low-speed low-power circuits

3.2768 Allows binary division to 100 Hz (32768 × 100 Hz, or 2^15 × 100 Hz)

www.patentstorm.us...

In the preferred
embodiment, the real time clock runs at a 32.678 kHZ rate which is a
binary number. A binary divide of 32.678 kHZ gives seconds as output.

Hope that helps.

yes, it helps...thanks. my question was more...how did the clockmakers also happen to coincidentally use this way before the advent of computers?

reply to post by ~Lucidity


IBM?



Just a guess

Look into the history of Constantin Girard of Girard-Perregaux. He developed the quartz movements that set this standard. The company has a history of quartz movements.

You also need to know something or two about tuning forks.

Originally posted by ~Lucidity
yes, it helps...thanks. my question was more...how did the clockmakers also happen to coincidentally use this way before the advent of computers?

Several people have also commented on the neat way most of western culture adopted decimalisation for currencies, and then the metric system of measurements - very handy for computers they say.

reply to post by ~Lucidity


Because Binary isn't solely relegated to the world of computers. It's been a form of mathematics since the number 0 and 1 was created. People used to use binary as a form of securing messages. It is only natural that we would use it as a form of mechanical and digital input/output systems.

Originally posted by SLAYER69
reply to post by ~Lucidity

 

IBM?



Just a guess

hmmmmm...do you mean that they made clocks using this standard in the late 1800s and early 1900s? thought ibm came about a little later than that. good guess i guess

reply to post by hinky


thanks, hinky!

reply to post by projectvxn


got it...it think. it's just amazing to me how it all worked out so well and how what they chose way back when made that leap so well. i guess i still don't quite get how watch and clockmakers decided on the standard, but hinky's clue will get me going. math baffles me but i was part of this discussion (well okay i listened to it) at work the other day, and no one seemed to have any really clear explanations as to how it was decided on, and we couldn't find anything online either. thanks.


[edit on 15-6-2008 by ~Lucidity]

After years of experimentation, watchmakers have generally settled on a frequency of 32,768 hertz (cycles per second) as offering the best combination for accuracy and efficiency. Large crystals oscillate more slowly, which reduces accuracy. Smaller ones oscillate much faster, but it takes more battery energy to slow the resulting frequency down for use.

The alternating current at 32,768 hertz then moves into an integrated circuit, where it is divided in half 15 times. The result is an electrical current alternating, with marvelous precision, once each second.

query.nytimes.com...

To sum this up
- 2^15: best trade off,
- power of two: simple integrated circuit to convert into seconds.