Making a Wax/Paper/Aluminium Foil Capacitor

About a year ago I had a post about Violet Rays / Violet Wands

I haven't been tinkering much with them in a year, but in the past few weeks, I've gotten back into the project. Modernized a few more cables, sorting out what works, what needs fixing...

I mentioned in my previous post I have a few with dead capacitors. I tried to use a M.M.C. of modern caps, but it just didn't feel right.

So this week was apparently capacitor week on hack-a-day (/hat-tip Rob for sending all the links my way)
http://hackaday.com/2011/05/09/roll-your-own-capacitors/
http://hackaday.com/2011/05/10/roll-your-own-capacitors-high-voltage-edition/
http://hackaday.com/2011/05/12/plastic-plate-capacitors/

So I had a dud capacitor out of a vintage violet ray, so I decided to tear it apart and see how simple it was.







When I unrolled the whole thing, it was very long.

2.5 inches by 12 feet (Foil) (the wax paper was about 3.25 inches wide)



Seemed simple enough. I mean come on... They were doing this crap 100 years ago.

There was also a nifty blurb about capacitors in this excellent website.

The blurb talks about using modern microwave capacitors. I looked around the lab and my apt for a spare, but I'd purged all mine, and all the ones from the lab look like they were sold at the garage sale. So I figured why not do it fully old-skewl... with wax paper and foil.

I hit up QFC, purchased a few rolls of waxpaper, and a roll of aluminium foil.

I rolled about 13 feet of wax paper out on the ground. Then 2 more sheets on top of the first. I measured out 3 chunks of 3.25 inches and cut them with a super sweet pizza-cutter like device.



I had previously rolled a little over 12 feet of foil onto a tube and cut it with an exact-o in 2.5 inch segments.



I wouldn't recommend it. I'll find a much better way next time. There were lots of tearing issues that made my 2.5 inch x 144 inch foil less than perfectly rectangular.



But all-in-all, it worked well enough.



Eventually, I got all the layers in a stack, weighted down with chunks of metal.



3 layers of wax-paper
1 layer of aluminium foil
3 layers of wax-paper
1 layer of aluminium foil

Then I started rolling, using a clamp to help me occasionally.





I ran into some serious troubles with the rolling process. All that waxpaper gets really slippery, the foil didn't want to keep centered... I was so focused on the roll, and how to fix it, I didn't get any pictures... thankfully Aimee was around!





The last few feet couldn't be saved, and I ended up chopping a bit over 2 feet off, and finishing with 2 rolls of electrical tape.

Here is me with the finished wrap trying to put on my best why-are-you-pointing the-camera-at-me?-face



Then Matt arrived with his plastic:



Yeah... supr-sekrit-project, I can't speak of it in this public place.

So anyway, we fired up the fondue pot of paraffin (old pictures, just showing what else Matt uses it for), and made sure the vacuum chamber was ready.

When the wax was liquid, and about 150 degrees F, a bunch got scooped into a glass and went into the vacuum chamber.



It was in there for 4 or 5 minutes. I got some video I might put on youtube later.

When it came out, it looked like this:



We tested the capacitance. it was reading about 133 nF. I was shooting for anywhere in the 80-150 nF range, so this looks promising.



I'll install it into my violet ray sometime soon and see what happens.

I did all of this down at Metrix (Thanks Matt and Aimee for being awesome! more great photos from their stream here).

Mindflex Arduino Hack

My friend and mentor 3ric lent me his mindflex for a project. The first step was to get it to output to a computer.

I hacked it to an arduino using this superb guide.

Short version.
Unscrew 4 screws
Solder 2 wires
Plug the 2 wires into an arduino
Download their code.

The folks at frontier nerds who did all the hard work, did their job well. This hack was shockingly easy. Got some pretty visualizations (also provided by the frontier nerds (whom I can't speak highly enough about)) tonight, but found this easy way to dump the serial data to a .csv via putty. I'm excited to gather some data.

Quarter Shrinker Explodey Malfunction Postmortem

Last weekend there was a pretty epic Quarter Shrinker accident.

A few nights ago Rob, Chicken, and I looked at the Quarter Shrinker at length to understand as much as we could about what the mode of failure was.

(Setup)
The multimeter had wires connected to the positive bus, and also to the giga-ohm resistor as a voltage divider, so the multimeter wouldn't be subjected to the full voltage of the charging cap.

(Disaster)
The problem is, the case of the capacitor is also connected to ground, so the multimeter was duct-taped directly to one big ground-plane.

We think there was a short somewhere inside the multimeter between the positive lead and the ground plane. This caused the multimeter to explode. In this explosion there was wire still had the alligator clip connected to the positive bus... as the multimeter blew apart, the other end of the wire swung around and connected (again) to the capacitor case. This caused a dead-short (with an unknown charge) across the former multimeter wire, which promptly vaporized.

(Photos)
Site of the former multimeter:

The vaporized copper blast where we think the dead short occurred:

Where the alligator clip was connected to the positive bus bar:

--Rest of the Set:--

My New Swift Microscope

So as I mentioned, I got a new microscope. Here she is:

Massive Summer Update

Too busy doing awesome stuff (and playing Starcraft 2) to blog this summer, so here is a short rundown.

In one day (July 24th), I sent my flip camera up on a kite, I took a sweet video of quarter shrinking, and lost my northpaw (which reminds me I need to order a new one).

I'm working with frit now in my fulgurite experiments, and getting pretty close to making fulgurites in arbitrary colors.

I've got all the parts to make a cloud chamber, and a budding radioactive collection. I just need to get off my ass and put it together.

I had so much fun taking and posting the previous microscope pictures, I decided to upgrade my microscope. Browsing ebay, I found some dusty, old, bio-lab-quality microscope someone found in a garage. It seemed worth at least $50 when I put in my bid. I won at $35 ($44 with shipping). I didn't check what it really was until I had received the win-notification. Its a Swift M1000-D, it seems to be from the late 70's, and seem to be priced at $400-$800 these days for a refurb. I love it. And I love ebay.

My other major equipment purchase recently was a big dewar I picked up at the UW Surplus Auction. It holds 35 Liters of liquid nitrogen. I got about 15 L worth and brought it down to Hackerbot Labs a few weekends ago. Much fun was had by many. I've received no small amount of shit for putting "a minor" (who shall remain unnamed) "in danger". I fully reject this attitude. I warned him that shit was VERY cold, and told him not to hurt himself. Any pain and/or suffering he may or may not have experienced was trivial and equivalent to scraped-knees learning to ride a bike. Besides, this is the "kid" who talked me into dunking my hand in liquid nitrogen the last time someone filled Dan's dewar and brought it to lab.

In other news, I've also just rearranged my work space, so my soldering station is out of Monica's room, and into my primary living area. With luck, this will lead to less procrastination... like maybe I'll finally put that cloud chamber together.

Hokay, pictures have been uploaded, so I'll make a couple separate picture posts.

NorthPaw Day One - Remember to Charge It!

Friday was the first real day of wearing the NorthPaw and was a little odd. I neglected to charge it Thursday night, so I think the battery was getting a bit low on Friday. Had a couple nifty experiences walking around getting used to the thing buzzing on my ankle. Escalators cause some weirdness. So does the wheelchair access lift when I'm sitting too close to the front of the bus.

Charged it last night, so I guess today is going to be my real first day.

Heading to Hackerbot Labs early today.

Got My NorthPaw and It Works!

My NorthPaw kit arrived yesterday from Sensebridge.

The northpaw is a compass that provides feedback in the form of 8 small motors (the kind that make your cell phone buzz) in an anklet. The northern-facing-motor buzzes slightly on your ankle, so you always know which way is north.

This is the kind of practical DIY transhumanism that makes me really excited.

Technical components are small and cheap. We can take all kinds of interesting sensors and put them in gadgets that provide some flavor of sensory feedback and neuroplasticity handles the rest.

At Maker Faire I had the great pleasure of meeting Eric Boyd of Sensebridge & Noisebridge who is responsible for the particular kit I got. He was as super cool guy. Friendly and full of great stories and great ideas. I've got nothing bad to say about this guy except for his hair, just kidding, I like his hair too.

Put the kit together last night and took it for the first test spin around the neighborhood. It was awkward and confusing. But I sorta started to get the hang of it... sort of, maybe?

It very much reminded me of the first few minutes of awkwardly playing a new video game with foreign controls, or a new class of controller. Which button is walk forward? [avatar fires gun] Oops... Is this walk? [avatar crouches]. How did I just fire my gun? [avatar self-immolates].

You need a little while in the game to map the controls so you can think "walk forward" and your hands perform via muscle memory. I wonder what my learning curve is going to be. I already have a little bit of "the eric dance" going on.

Here is a video with him talking about the thing:

Eric Boyd - The North Paw: A Haptic Compass Anklet from Loren Risker on Vimeo.