[time-nuts] Thunderbolt, Rb,

Hal Murray 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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