Sunday, March 2, 2008

Computers, Watches and Living at Lower Temperatures

For some time I have been experimenting with living at ever lower temperatures, that is, with use of ever less fossil fuels for heating and cooling. Typically at this point I set my thermostat to 50F, but I actually have the heating system off during the day and much of the night. At the time of this post, it is sunny outdoors and the temperature at my workstation is a balmy 58F. There are impacts that I continue to seek to identify. Most of these are qualitative impacts, such as the fact that my liquid peppermint soap clouds up, and my ViewSonic monitor does not start up if it has been off at low ambient temperatures for a day or so. This posting addresses the impacts on computer clocks, which is a natural concern for many people.

This from Wikipedia on March 2, 2008 (

A crystal's frequency characteristic depends on the shape or 'cut' of the crystal. A tuning fork crystal is usually cut such that its frequency over temperature is a parabolic curve centered around 25 °C. This means that a tuning fork crystal oscillator will resonate close to its target frequency at room temperature, but will slow down when the temperature either increases or decreases from room temperature. A common parabolic coefficient for a 32 kHz tuning fork crystal is −0.04 ppm/°C².

In a real application, this means that a clock built using a regular 32 kHz tuning fork crystal will keep good time at room temperature, lose 2 minutes per year at 10 degrees Celsius above (or below) room temperature and lose 8 minutes per year at 20 degrees Celsius above (or below) room temperature.

Thus for ordinary applications in the home and office, there is no significant problem with "clocks" even if one lives at 50F or 100F.

No comments: