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David Knaack
1,322 followers
1,322 followers
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Filtering Silly Putty
Years ago, probably about 1995 or thereabout, I hosted a 100lb Silly Putty group buy. I wrote a little web page using JSP, Perl, and Firebird, and used it to let dorks like myself sign up to buy Silly Putty in half-pound increments. I think I ended up with ...

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Silly Putty, separated. On the right is the putty base, mostly  cross-linked polymethylsiloxane. In the middle is the tan colorant, which I've done an awful job of powdering. On the left is the lint and grit that the putty has picked up over the years.
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A simple chemistry process. This Silly Putty had some lint and grit in it, so I thought I'd try dissolving it and filtering out the solids. After this I centrifuged the solids down, poured off the solvent, then rinsed the solids twice more. Evaporating the solvent left the translucent putty. The original tan colorant along with the grit and lint contaminants were dried and powdered. If screened to remove the grit and lint, the colorant could be returned to putty to reconstitute the original putty, sans contaminants.

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Growing sulfur #crystals tonight. A few grams of sulfur powder dissolved in 95C xylene, then allowed to cool. Also some debris chipped off the edges of the magnets I was using to stir the solution.
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Van Overhead Console
I'm building a new overhead console for the '93 B250 conversion van I've recently acquired: After driving it around a while I decided that it doesn't have enough storage up front, and there isn't a good place to mount my FT-8800 amateur radio transceiver. A...

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What's in an Inexpensive Centrifuge?
I've added a low-speed centrifuge to my lab equipment. It is a Chinese-made device sold on Amazon by Hardware Factory Store . It works well, I can recommend it if you need a basic centrifuge. I was curious what was inside, what does $110 get you? Looks like...

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Here are some #mushrooms I found in #Missouri on #October 11, 2014.
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2014-11-10
11 Photos - View album

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Crystal Chamber PID Tuning
Since I'm trying to use a PID controller to keep the chamber temperatures under control I need to tune the PID parameters. And since this is designed to run for hours at a time, and because I'm crap at PID tuning, getting it right it is very tedious. Also p...

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Crystal Chamber Controller Interface
The code I've been using to run the temperature controller for the crystal chamber so far has been pretty bare, just the core PID loop. I don't have it tuned yet, but it's generally functional, so it's time to start getting it in shape to be an appliance. A...

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Crystal Chamber Temperature Controller v0.1b
I cobbled together a simple temp controller to try to get a feel for what it'll take to make one that will work for my temp controlled crystal-growing chamber. For this first iteration I've just got a simple PID-controlled heater, LM75 I2C temp sensor, and ...
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