I ain’t afraid o’ no ghost

With the Pac Person costume complete, it’s time to crank out some ghosts. Construction is pretty much just like the Pac Person, except there are two strands of lights instead of one. Every ghost gets a blue strand (for when it’s vulnerable) and a body color strand (red or green) for those times when it has an insatiable hunger for bloodPac Person.

Knowing that making Pac Person required about five hours to sew one strand of lights on, I decided I needed a faster approach. I set up the fancy quilting hoop – it’s an embroidery hoop on a stand. I can see the point behind it.  For quilting, where you would have a lot of stitches in one place before you have to move the fabric, it ought to be pretty good.  But for sewing lights on a piece of fabric?  I spent more time taking the fabric in and out of the hoop than I did sewing.

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I needed a solution. Over dinner I mentioned to Susie that what I needed was a quilting frame about five feet in diameter. About the size of the kitchen table. And that’s when she realized that the kitchen table could be a quilting frame.  We pulled the two sides apart, neglected to insert the leaves, and there you have it.  Not quite as good as having a five foot diameter frame, but close enough.  Also – if you try this at home, it’s a really good idea to sew both strands at the same time.

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Waka Waka…

In previous posts, I’ve gotten a sewing machine and I’ve bought wire lights.  I’ve also made allusion to ghosts.  By now it should be obvious…

Real Life Pac Person.

(The console games attempted to promulgate a false gender binary on susceptible young players.)

I managed, before this weekend was out, to sew a Pac Person cape and attach yellow LED wire lights to it.  I did it not because it was easy, but because it was fun.  Making the cape is the easy part. It’s a two-fold cape with one section removed to yield a 3/4 circle cape.  Neck cutout is about a 12″ collar.  Velcro allows it to be taken down to half that, or a velcro extension tab expands the neck to about 21 inches.  This should fit anyone from eight year olds to All Pro defensive linebackers.

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LED coverage is stronger on the left side than the front, and I’m debating whether to go back in there with another, shorter strand of lights or whether to just go with it.  All the players are going to know this is Pac Person – it’s yellow, it’s hitting Power Pills, and it’s running like its life depends on it when the blinking stops.  Illumination brightness is more than adequate for indoor play.  I expect it will burn through three sets of batteries in a seven hour installation.

Those LEDs took about five hours of hand sewing.  Oh yeah.

Raspberry Pi – First Light

The big upcoming project uses the Raspberry Pi for brains.  Actually, it uses four of them, one per ghost.  Last week I got them powered up and actually started configuring them.  Simple USB-WiFi adapters are plenty good enough for what I’m doing, and I’m pleased to report that they work flawlessly.

In fact, everything works flawlessly.  This is a totally “plug it in and it works” kind of thing.  Plus, the Pi comes with both Minecraft and Mathematica.  This is the first time in two or three years I’ve felt complete, unadulterated joy from a computer.  The purity of the experience is remarkable.

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(brightness, contrast, and effective gamma have been tweaked to compensate for the exposure being completely blown out by the bright monitor behind it).

CPU power feels about like a PII-450 running a modern distro, but the microSD card feels very slow.  No matter – it won’t be heavily taxed in the upcoming application.

Built Like a Battleship

New addition to the Secret Underground Laboratory:

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A Singer Model 99K. Serial number strongly suggests manufacture in 1946. The 99 family was considered a portable sewing machine – at 31 pounds, you could move it anywhere an ox could drag it, and this model is considered “half size”. The machine positively radiates solidity. Accepts standard, modern needles; I’m not sure yet about bobbins. I tried a “New Singer” bobbin and it was too thick to fit in there. I know they stock two different sizes at the fabric store, so I can try the other size and see if I get any luckier. Otherwise, I have the four bobbins that it came with, so I should be OK.

Edit: Bobbin is a Singer Type 66. These are still fairly common, and fit oodles of modern machines. Should have been obvious: a 99 is a smaller 66.

Obligatory action shot:

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Someone check the doorbell…

My house was built in 1929.  The doorbell is presumed to have come later, but maybe not much later.  It had been getting a little unreliable the last few years (!!!) but it all came to a head two weeks ago.

Anyway, the first step to healing is to admit you need to disassemble the thing.

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And a detail of those switch contacts:

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So, those machine screw ends are shorted together when the doorbell button pushes the brass spring down onto the (corroded) ends of the screws.  Repair methodology: file the metal parts until they’re shiny and new looking.  The material that the threads screw into is about 50 laminations of plain old paper.  Amazingly, it has held up through at least sixty years of outdoor use.

Wire Lights

For an upcoming project (hint: the big reveal will be April 25th, but you’ll get a good glimpse of it here before the Big Day) I need a whole bunch of LEDs I can put onto some fabric. The traditional solutions have problems.  Typical “flexible PC board” tricolor LED strips are too stiff and too expensive.  A ton of discrete LEDs is too time consuming and, except at surplus prices, way too expensive.  Enter “Wire Lights” – two parallel strands of copper bell wire with surface-mount LEDs soldered between them.  Wired in series with the entire strand is a series dropping resistor sized to make the whole string light up at 5 volts.  Specified current draw is 1 Amp, but I’m going to need to measure that.  Not really visible in daylight, but they show up well under “normal” indoor illumination and they’ll be great in a slightly dimmed exhibition space.  Hmm…

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Fixing Battery Corrosion in a Mini Maglight

About twenty years ago or so, I bought a Mini Maglight to supplement one I had bought about twenty-seven years ago. Both of these use the itty bitty incandescent bulbs, neither one being anywhere near new enough for the fancy modern white LEDs. They work, anyway. Or, they did – until the batteries in the newer one leaked.

Normally, this wouldn’t be a big deal. You replace the batteries and get on with your life.  In this case, though, there was a complication. The leaking battery was completely stuck inside the flashlight barrel. I tried banging the open end against the back of legal pad, and I tried that a lot. No good.  Evidently it was time to take it apart and push out the dead cell.

There are at least two versions of the incandescent Mini Maglight running around, and my two were of different generations. I had taken the old one apart before, but the new one was a bit befuddling. First, field strip the easy parts – take out the bulb and then just pull on the “do not remove” outside bulb holder until it pops off.

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This leaves you with the inside bulb holder, the barrel of the flashlight, and one immovable battery. It’s time to move the immovable. I didn’t have a pin punch the right size, so I grabbed a cheap, junky Torx screwdriver that would fit in the access holes at the very back of the inside bulb holder and whacked it with a hammer.

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This resulted in squat. I was deforming and slowly hammering my way into the battery instead of pushing it out. Judo is too subtle, I’m switching to Kyokushin: hit it harder.  About ten good whacks with a small hammer and I started to actually move the battery.  A bunch more and it finally came out.  Finally, switch to a larger drift (in this case a, uh, Uniball Vision ballpoint pen…) and gently tap on it until the inside bulb holder falls out of the threaded end.

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Inspection of the flashlight barrel revealed the reason the battery wouldn’t come out – when the cell leaked, it dumped potassium hydroxide into the bore.  This reacted with the aluminum barrel forming hydrogen gas (always a crowd pleaser) and potassium aluminum tetrahydroxide – aka “crud”.  Oh, and it also formed a corrosion pit in the aluminum – luckily not all the way through the metal.

Cleaning out the corrosion is done with a 20ga shotgun bore brush threaded into a cleaning rod and the tool spun with a drill.  Wear a dust mask and eye protection.  Bear in mind that the friction will heat up the aluminum, so pay attention and stop to let it cool at intervals.

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Assembly is the reverse of dismantling.