Hi Mike,

" would suggest that the grandfather clock pendulum may swing a bit too slow for the LED image to look like a non flashing display"

You can say that again and again !! My own posting looked silly after I had hit the post and read it back.

Yes it is not as simple as it looks.

Yes the swing rate should be high as mentioned by you; And this also will be decided by the swing span that we plan to have; More of this and we are talking of raising the swing speed further. In fact this is not a swing per-se . It is a low frequency vibration !!

One method is to fix the beam as a pivoted crank and drive the slotted flywheel at constant speed - with this 100Hz plus may not be a problem.

Raghu