[time-nuts] Good scopes under $40 was Thunderbolt, Rb,

[Robert Atkinson]

--- On Fri, 21/5/10, Hal Murray <hmurray at megapathdsl.net> wrote:


From: Hal Murray <hmurray at megapathdsl.net>
Subject: Re: [time-nuts] Thunderbolt, Rb,
To: warrensjmail-one at yahoo.com
Cc: "Discussion of precise time and frequency measurement" <time-nuts at 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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