Mechanical-Digital Steel Ball Clock

Re:Mechanical-Digital Steel Ball Clock by globular-toast on Monday October 12, 2020 @06:52AM (#24753161)

I wonder, is it possible to make a magnet that's always on and uses power to switch it off? Kind of like how air brakes on trains work.

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Re:Mechanical-Digital Steel Ball Clock by lebuffon on Monday October 12, 2020 @10:26AM (#24754645)

There are classes of relays that worked like that in old portable broadcast video recorders. Essentially a coil around a magnet and the coil was used to strengthen or weaken the flux with a pulse of current. The armature was spring loaded but not strong enough to release from the permanent magnet unless a pulse of "buck" current was applied.

Old timey stuff.

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Re:Mechanical-Digital Steel Ball Clock by andre_ramos on Monday October 12, 2020 @12:17PM (#24756024)

Yes, you add a magnet in the middle of the coil and actuate the coil with opposite polarity to cancel the magnetic field

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