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bio website Grieu
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seen Apr 1 at 11:43

Mar
17
comment What makes a wrist-energized gyroscope rotate faster?
@user3058846: when something gains speed by friction (in some Galilean referential), in all examples I know, this is thanks to something with a faster speed (in that referential). As tentatively explained in the updated question, I do not see that this is the case here, at least if I consider rotation along the rotor's axis (which, admittedly, is not speed gain in a proper Galilean referential; perhaps what I perceive as a paradox comes from that).
Mar
17
revised What makes a wrist-energized gyroscope rotate faster?
Update with interrogation on why friction can increase the spin rate, and question 2
Mar
16
revised What makes a wrist-energized gyroscope rotate faster?
Fix typo
Mar
16
comment What makes a wrist-energized gyroscope rotate faster?
@user3058846: but usually, friction tends to slow motion, be it linear or rotational. If friction plays a role in the rev up (and I'm ready to believe that), it must be by transferring a torque to the rotor.
Mar
16
asked What makes a wrist-energized gyroscope rotate faster?
Aug
20
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Jan
7
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Jan
5
accepted Limit of human eye flicker perception?
Jan
3
comment Limit of human eye flicker perception?
Any pointer to your brother's research/thesis? And +1 for suggesting alternatives to plain PWM in implementing the dimming while increasing the flicker frequency.
Jan
3
comment Limit of human eye flicker perception?
The capacitor across the LED needs to be several uF, thus has non-negligible cost and space. Also it multiplies the inrush current (for initially loading it) by a factor of about 3, exceeding the maximum rating of my output port. Outsourced PWM is not an option for same cost and space reason. Really my only option is to raise the flicker frequency.
Jan
3
comment Limit of human eye flicker perception?
Yes. My "I disregard purposefully moving one's head relative to the LEDs" should be re-stated as "LED does not move relative to head of observer".
Jan
3
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Jan
3
revised Limit of human eye flicker perception?
correction
Jan
3
revised Limit of human eye flicker perception?
Add relevant link
Jan
3
comment Limit of human eye flicker perception?
I do have an incentive to lower the frequency: the PWM is in software, running simultaneously for 10 pins of some tiny CPU with individual dimming factor, and there are other stuff to do. From your answer and other sources I get that 60 Hz could be detectable in the dark, 1 kHz would not, but I'd like to reduce that interval. Surely that must have been studied.
Jan
3
awarded  Editor
Jan
3
revised Limit of human eye flicker perception?
Explain 48 or 72 Hz shutter frequency
Jan
2
asked Limit of human eye flicker perception?