--- On Fri, 21/5/10, Hal Murray <[email protected]> wrote:
From: Hal Murray <[email protected]> Subject: Re: [time-nuts] Thunderbolt, Rb, To: [email protected] Cc: "Discussion of precise time and frequency measurement" <[email protected]> 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. _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
