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Twin articles on Twin Quartz
"Twin Quartz" was a Seiko marketing term that applied to two different high accuracy quartz technologies, both commercialized in 1978, originating respectively from the two 'factories' of the Seiko Group:
Daini Twin Quartz (cals. 92xx, 97xx, 96xx)
- two quartz crystals wired in parallel in ONE oscillating circuit
- vibrating at the SAME frequency
- based on 1960s inventions for quartz master clocks
- thermoinsensitivity not thermocompensation
Suwa Twin Qaurtz (cals. 99xx, 94xx)
- two separate oscillating circuits, each with a quartz
- usually at different frequencies
- frequency difference is basis for computed corrections
- basic concept credited to Yoshikazu Akahane
Links to the Japanese-language technical papers for both types are provided.
Bonus: Twin Mode (cals. 90xx and some variants 77xx and 95xx)
- one quartz
- early 80s Seiko invention
- thermoinsensitivity
but not a full writeup: https://chmandaue.substack.com/p/seiko-majesta-vjg040-9063-5030
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Twin articles on Twin Quartz
"Twin Quartz" was a Seiko marketing term that applied to two different high accuracy quartz technologies, both commercialized in 1978, originating respectively from the two 'factories' of the Seiko Group: Daini Twin Quartz (cals. 92xx, 97xx, 96xx) - two q...
