I see it says "T Swiss - LIC ATO" The ATO patented movement is about as simple as these things get. At its most basic, it only uses one transistor. This may not make for the most stable oscillator, design but in this use case, they are actually relatively good, since they rely on a fairly conventional mechanical balance to control the oscillator frequency, rather than an R/C circuit, which would typically be less stable over the working temperature range.   (schematic shamel
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