[time-nuts] Thunderbolt, Rb,

[Hal Murray]

> 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.
  http://exs.exploratorium.edu/exhibits/oscylinderscope/


> 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.



>From the initial message
> As part of the SF Bay Area Maker Faire this weekend, I'll be showing a
> Thunderbolt GPSDO and a FE-5680A Rubidium disciplined oscillator, both
> connected to a $25 flea-market oscilloscope. 

Can you really get a useful scope for $25?  What's it like?

What's a low end A/D on a USB dongle go for?


-- 
These are my opinions, not necessarily my employer's.  I hate spam.