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Madbodger

Member Since: January 12, 2008

Country: United States

Profile

Programming Languages

C, Java, XSLT, assembler

Expertise

Vacuum tubes, neon, microcontrollers, electronics

Interests

Neon, reading, building, making

Websites

http://www.vitriol.com/ http://bodger.dreamwidth.org/

  • Some folks were chasing down the people behind a quack medical treatment, and one actually found a dissertation “explaining” it. It’s chock-full of buzzwords (including a completely bogus reference to Lorentz force). https://dc.uthsc.edu/dissertations/377/

  • The space age? That was half a century ago.

  • I tried this, but XCTU wouldn’t talk to my XBees because their firmware was too old. The fix was to go ahead and follow the dialog to update the firmware profiles in XCTU and select the “legacy” option. Then it recognized the 10E6 firmware (from 2009) and I was able to update to the current version and proceed.

  • Strapping to connect the level shifter to V1 or V2?

  • There is an IR interface for X-10 (IR543 or IR7243), I imagine this would work with it.

  • There’s a fair amount of interest in old Heathkit gear. They made a bunch of cool TV test stuff, and while analog TV isn’t broadcast much any more, people still find use for it. What do you have? Pattern generator? Vectorscope? VTVM? GDO? Demodulator probe?

  • I was guessing the other tube was a 6C4, and sure enough, it is. It’s basically half a 12AU7. You can find the manual here: http://tubularelectronics.com/Heath_Manual_Collection/Heath_Manuals_S/SG-8/SG-8.pdf Sure enough, that connector isn’t a PL-259, just a generic microphone connector which was pressed into service for a lot of test gear (VTVMs, oscilloscopes, etc.) back in the day. Everybody made ‘em, but I don’t know of a standard name. It’s probably a 5/8-27 thread, like Amphenol 85-75MC1F, Switchcraft 2501F, or J-30.

  • Oops, I missed a word: aluminized mylar: a very thin layer of aluminum on a mylar substrate. I tried cleaning off the decorations with flux remover, which worked fairly well, then I cut out the sensor shape, which was an amazingly fiddly process, with the very thin material that wanted to curl up. Then I removed the label from a Sparkfun box with a heat gun, which left a sticky surface to which I adhered the aluminized mylar. Then I used 4-40 nylon screws to attach strips of copper foil to the corners and hooked it all up. No dice. While I had measured some pieces of it and got very low resistance (fractions of an ohm), the piece I had made appears to have discontinuities in it, probably scraped the aluminum while scrubbing/cutting/attaching it. It really is thin aluminum, I can see light through it. I think I’ll go shopping for a non-printed aluminized mylar balloon or one of those “space blankets”, which might not be as ready to curl up.

  • As for the Thomson galvanometer, we do have the advantage these days of small, lightweight lasers, so you don’t have to wait for a sunny day and arrange everything just right to get a beam. That would be a wonderful combination of old and new technology!

  • I’m still playing with it. I built a transimpedance amplifier out of an LF356 and hooked it to a meter to yield a much more sensitive meter. I’m powering it from a 9V battery for both low noise and so I can float it at whatever voltage is required. Pushing a microamp into it gives good meter deflection. I’m playing with a mylar balloon to get a thin enough foil. I’ve verified that it’s conductive, but I’m having trouble making good contact with it, as this particular balloon is decorated and the ink isn’t conductive. I’ll see if I can remove it with solvents, but I may have to go buy a plain silver one to play with. I’m also thinking I could buy some fake gold leaf from eBay and try that. I figure I can make contacts with either conductive paint, or try lightly clamping copper foil for leads using something like plastic paper clips – I learned my lesson about using anything ferrous anywhere near the big magnet!