The Invisible … Beam?

One of the most exciting things you can do with a Scope Clock is to simply look at it from behind! In many CRTs, the anode coating (a conductive black surface sprayed onto the inside of the glass) doesn’t extend all the way to the screen – leaving a nice gap of clear glass from which to observe the beautiful electron beam.

Ha – you can put down your magnifying glasses now.

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The trailing effect

A colleague asked me whether the trailing effect you see on the seconds hand was a photography trick, or something actually visible to the human eye.

Trailing effect

Yes, the trailing effect is real, and it’s thanks to a characteristic of the CRT’s phosphor screen called persistence.

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