--- On Fri, 21/5/10, Hal Murray hmur...@megapathdsl.net wrote:
From: Hal Murray hmur...@megapathdsl.net
Subject: Re: [time-nuts] Thunderbolt, Rb,
To: warrensjmail-...@yahoo.com
Cc: Discussion of precise time and frequency measurement time-nuts@febo.com
Date: Friday, 21 May, 2010, 6:52
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?]
What else do they use? Voice coils took over from steppers many years ago when
servo head travking started. I'm not aware of any alternative.
I
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?
You can in the UK. I just picked up a old Advance dual trace 20 MHz unit at a
hamfest for £10 ($15). It was for a work mate to use at home. Works fine and
even he adamits it will teach him a lot more than the push autoset on a
digital. Previous Hamfest I got an HP 1740A 100MHz, dual trace, delay TB etc
with manual for £25 ($37) for myself (realised i did not have a good analog
'scope). Have also won an HP 1980B oscilloscope measurement system DSO (HPIB
contolled) with the 1965A 10 picosecond resolution counter option for £26.65
($40) For comparison petrol (Gas) just hit $6.93 per US gallon here. it costs
$100 to fill the wifes Ford Focus!
What's a low end A/D on a USB dongle go for?
Anything with useable software $35
Robert G8RPI.
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