Archived posting to the Leica Users Group, 1999/06/14
[Author Prev] [Author Next] [Thread Prev] [Thread Next] [Author Index] [Topic Index] [Home] [Search]Lucian Chis wrote: > And they designed > the first mass-produced quartz watch in 1969. And so they imposed the > frequency of the quartz (32.77 kHz (approximately)) which all quartz > watches use nowadays. > Sort of like Leica and 24X36mm format! > > Lucian Lucian, This may be a late replay, but better late than never. The quartz frequency of 32.77kHz (32,768 to be exact) was not invented or specifically started by any watch maker. It is a natural binary progression when a resulting frequency of 1 Hz is required. I used some old circuits which used this frequency to arrive at the 1 Hz requirement. However in the early days, the quartz crystals for this frequency where quite big and expensive to make. They where normally contained in an evacuated glass envelope. For this reason a crystal with the frequency of 3276.800kHz was used. This crystals where small and cheap to manufacture. they also exhibited a better temperature coefficient. The drawback was, the binary part of the division only went down to 100Hz and to arrive at 1Hz, a decadic divider had to be used. The modern crystal used in watches are manufactured with a completely different technique. They are extremely small. Temperature stability is not a big issue, because the temperature of a wrist watch when worn is quite stable. The relatively low frequency of only 32 and a bit kHz also helps to keep battery consumption down. The current consumption of the C-Mos circuitry used in watches is directly related to the operating frequency used. Regards Horst Schmidt