[time-nuts] Thunderbolt, Rb,
hmurray at megapathdsl.net
Fri May 21 05:52:06 UTC 2010
> Tomorrow, the school demo will be a paper scope made out of a yard stick, a
> marker, and wall-chart paper: one student holds the oscillating yard stick,
> a second pulls the paper steadily, and a third times it. Afterward, they
> count peaks and divide by time.
Neat. Scopes are fun.
The Exploratorium has a nice exhibit. It's setup to look like a giant guitar
so you start off with the idea of strings vibrating. Some of the frets are
white lines on a drum you can rotate. It works amazingly well.
> Next student demo is the scope made out of a laser and hard drive with a
> mirror on the voice coil.
[When was the last time they made hard drives with voice coils?]
I don't see it yet. Are you tilting the mirror or just making a small
picture? Or is there some mechanism I'm missing?
> For the real scope work, we won't show the Rb to the kids; they'll get an
> iPod with music on the scope, as it's more relevant to them.
I like it. Is the iPod preloaded with neat "tunes"?
Do you have any fancy scopes for big kids? One great way to have fun with a
digital scope is to try to show the picture from a old skiers avalanche
beacon. It's a short pulse of 455KHz AM modulated with a few KHz. The rep
rate is about 1 second, too slow for most analog scopes. There are all sorts
of opportunities for aliasing or missing a significant part of the picture.
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