A Mechanical Neon Oscilloscope

For instance, it was critical that each row of punched holes in a card passed under the brushes at the right time for the computer to read the values. The dynamic timer would show 12 orange lines in a circle, indicating when each hole was being read. If these lines were in the wrong position, the brushes were adjusted until the timing was right.

You can see it in action halfway down my page about the card reader: http://www.righto.com/2018/02/repairing-card-reader-for-1960...

Such devices actually existed and were common in the late 19th century --- they were called oscillographs. The first few pages of this 1915 book have some details on these devices, including the one in the article:

https://archive.org/details/wirelesstelegrap00zennrich

[...]

>"The tube used is similar to the familiar neon lamp that many an indicator or night light was made from. The difference is the electrodes are in a line rather than parallel." [...] "If you were to connect this to an alternating current source, the appearance would be two glowing areas at each electrode. To the naked eye, this would appear constant. Just like your night light. Now if you could effectively increase your visual shutter speed so to speak, you could catch the increasing amount of glow…followed by the decrease…and then the increase upon the other electrode and so forth…..all within the 60Hz line frequency applied to it."

In other words, something which is, in actuality, oscillating -- is appearing solid to the eye of the observer, because the eye lacks the frame rate to observe the oscillation unaided...

I wonder, in how many other diverse areas of Physics, this same principle might also exist...

https://en.wikipedia.org/wiki/Mirror_galvanometer