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Topic: temperature compensation crystal oscillator (Read 6817 times) previous topic - next topic

bigbuck83

has anyone ever replaced the clock crystal with a "temperature compensation crystal oscillator" or tcxo I believe for short..... I am I need of ridiculous timing accuracy but I am finding little info on this topic anyone out there have any ideas or sugestions

MAS3

A long time ago (somewhere in the eighties) i saw an Elektor article mentioning a "furnace".
That was a thermal isolated metal chamber heated by a transistor (i think).
(The transistor and the oscillator were inside the chamber).
By keeping the temperature at some higher level as the surroundings, one didn't need to do extra compensation i guess.
I'm not sure what the article was telling but i remember it was mentioned.

Must be better / easier ways nowadays.
Have a look at "blink without delay".
Did you connect the grounds ?
Je kunt hier ook in het Nederlands terecht: http://arduino.cc/forum/index.php/board,77.0.html

bigbuck83

Does anyone know how well arduino uno r3 keeps time......... I am using this board to run a world clock and am needing very accurate time over a long period.. which the uno r3 may be able to provide I am just wanting to make sure....... I just don't want to be losing seconds and in a week be off by minuets

MAS3

Have a look at "blink without delay".
Did you connect the grounds ?
Je kunt hier ook in het Nederlands terecht: http://arduino.cc/forum/index.php/board,77.0.html

bigbuck83

yes I see something was discussed but I still don't feel like that answered my question really...if I let arduino uno r3 run for say 2 months is it still accurate within a minute..... this clock I am repairing has the capability to read time down to 1/1000 of a second is the arduino going to keep the right time at such a small reading

Jack Christensen

Just to be clear on the difference between accuracy and resolution. Being able to read a clock to a millisecond (.001 sec) describes its resolution. Being correct within a minute over two months describes accuracy. The two aren't particularly related.

Now, does this properly describe the requirements? Accurate to one minute over two months, and millisecond resolution?
MCP79411/12 RTC ... "One Million Ohms" ATtiny kit ... available at http://www.tindie.com/stores/JChristensen/

bigbuck83

Yes this is correct I need both..... more importantly is the accuracy  I have a sketch written and am currently running my most sensitive clock to see the accuracy of my current set up..... so far after running all day it is right on the money I was just hoping to get some idea of what I can expect over a long time period

bigbuck83

I forgot to add that these clocks are analog and are old....... originally engineered  in the late 60's so  I am not sure if this clock can keep up with the arduino as is this pic may help you visualize

bigbuck83

this may work better the first pic didn't load or something

Jack Christensen

So what accuracy is needed? I don't have an R3 but last I knew, Unos had ceramic resonators which are on the order of ±0.5% accurate, which most people wouldn't find acceptable for a wall clock.
MCP79411/12 RTC ... "One Million Ohms" ATtiny kit ... available at http://www.tindie.com/stores/JChristensen/

Jack Christensen


this may work better the first pic didn't load or something


Interesting looking clock! What is it used for (or maybe I should say what was it originally used for)? What technology does it use, do you have any of the original specs?
MCP79411/12 RTC ... "One Million Ohms" ATtiny kit ... available at http://www.tindie.com/stores/JChristensen/

bigbuck83

it is a world clock and this is the master I have 15 slave clocks that run based on this main clock as for specs no I have a busted up manual that is in German so it isn't much good I have re- wired the entire thing and am currently putting it all back together and testing but I fear the Arduino isn't going to give me the accuracy I need over a period of time .......how do I correct this

Jack Christensen

The Maxim Integrated DS3231/32/34 RTCs are popular, they have temperature compensated crystal oscillators and are accurate to ±2ppm from 0°C to +40°C. Macetech makes an RTC based on the DS3231 called the Chronodot, it's available at several of the popular sites, Adafruit, Sparkfun, etc. etc.
MCP79411/12 RTC ... "One Million Ohms" ATtiny kit ... available at http://www.tindie.com/stores/JChristensen/

bigbuck83

well now what a nifty little gadget seems pretty straight forward I guess the chronodot is easy to use I am using 2 L298d H-bridges what tutorials could you recommend.........I would like to see it used if posssible

Jack Christensen

Yes nifty indeed! Do you mean tutorials on the Chronodot, or on the H-bridges?
MCP79411/12 RTC ... "One Million Ohms" ATtiny kit ... available at http://www.tindie.com/stores/JChristensen/

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