On 5/22/2019 1:17 AM, geoff wrote:
Looks like the unit natively runs on a RC-based local oscillator.
The 60Hz mains frequency (x2=120Hz) is only used for the 'Calibrate'
function, and the unit can be calibrated equally well from a precise
musical-note tone.
Did you find a schematic somewhere? I seem to remember mention of a
synchronous motor driving the strobe disk, but that might have been
another model. Seems reasonable, though, to be able to adjust the speed
of the strobe disk so you can "zero" it on an off-pitch piano or an
orchestra that likes to play to an A different from 440 Hz.
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