12/2 Casual Meetup – Change of Venue

November 30th, 2009 by noise

The next casual meet-up will be held at the house of noise (a.k.a. Secretary Pat Arneson). To take maximum advantage of the changed venue (and frankly because I’ll be ready for some visitors after a few days of an empty house) people are welcome to show up any time after 5pm. Let’s also do an informal potluck for anyone that feels like bringing something. I will try to get together a pot of clam chowder or chili.  Bring your own beverage of choice.

Most importantly, bring something to show off or play with, especially those things that you wouldn’t normally feel comfortable bringing to Common Roots (hmmm, lots of room for misinterpretation/misuse in that sentence).

Here is the map. My house is on a hill, so if there’s something you don’t feel like dragging up the stairs feel free to drive around back in the alley.  There will be space enough for a couple of people to park.

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Drone Lab Build

November 22nd, 2009 by Paul Sobczak

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Casper Electronics is offering a new kit called the Drone Lab, I pre-ordered one and just finished putting it together this afternoon and I am pretty happy with it. A few thoughts on the offering, first off I am really impressed at what Mr. Edwards of Casper Electronics has been able to feel out after playing around with circuit bending for so long and I am really impressed at the quality of the design being that I don’t think he has any formal training, read this as “designing electronic circuits does mean electrical engineering degree” and that is really comforting. I really liked the feet that are included, they are little round rubber things and they work out nice as stand offs. The design documentation minus the little mistake that was found right away were excellent, I really enjoyed the image nature of it as it leads to much less hunting for the screen printed numbers.

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Resistors, Capacitors and Transistors attached.

As far as the sonic actuality of the drone lab there is a surprising amount to explore here 4 tunable/Oscillators , a mixer, distortion stage, Low Pass Filter Stage, Band Pass Filter, and a Tremolo bank, as well as a place to input audio. One of the most interesting parts for me is getting the Tremolo bank up and running (556 timers) and using it along with some subtle knob manipulation, and this is was is included in the video below.

Total Build Time About 4 hours, not counting having to run to Radio Shack to pick up some more solder, As this is a Casper design Mods and Upgrades are allready in the works!

Living in the Future with GPS

November 19th, 2009 by Paul Sobczak

cabinet

Last week Cabinet magazine released PDF’s of their archives to subscribers (you can also purchase individual ones) and I took advantage starting with the first issue. I was intrigued by an article titled: The encryption wars , An interview with Eben Moglen. Written in 2000, besides touching on the topic of  cartography, of which I am fond, it predicts, that people would one day be walking around with GPS enabled devices and great (crowd sourced) maps will come from it.

Do you think ten years from now we’ll see
maps published showing the version of the
United States that’s being released now,
with these abrupt transitions from crystal
clarity to fog?

Mapmaking is a very interesting subject in
general, because when everybody in the
country is carrying GPS equipment, one
kind of mapmaking that will be absolutely
possible consists of the whole structure of
what we think of as free data. That is to say,
people voluntarily walking around with GPSequipped
cell phones donating the stream
of their information to a mapping database
which will be a very accurate map of everywhere
all the time.
Have you heard of any project like this
today?

I’m not aware of any. But you can see that
it will happen. Data streams will exist, and
there will be a kind of decentralized geographic
information service structure. But
like a lot of free-software activity, this will
self-organize as people perceive the need
or the possibility. It won’t organize ahead
of that perception. In our movement, we
get accustomed to the idea that what people
think is neat or needed, they’ll do. As the
net makes various kinds of collaborations
possible that have never been possible
before, people will do things collaboratively
in new ways. Part of what I’m trying to do
myself is to understand the political
economy of a world full of that kind of
content sharing.

JTbarclay wrote on the forum the other day, about just that, user created maps enabled by GPS.

Now I’m using Waze and loving it. The biggest difference is that waze is a full on crowd sourced navigation app with the ability to report road hazards, traffic, and speed traps.

Crowd sourced because the whole map is generated by people driving around. It started out in Israel where a couple hundred thousand users completely mapped out the entire countries roads just by doing their daily driving. However, the US version started with the census bureau’s free maps as a base.

As you drive around your car become pacman and you gobble up dots on unconfirmed roads. Adding new roads is pretty easy. The online editing map is pretty cool. I just drove through a new neighbor hood near my house, and then went online and added the roads on top of the route I drove. After about a week it showed up on my phone and I drove over it again to eat the “cookie points” and confirmed the road was there.

The navigation part is still pretty weak, but it learns fast. I wouldn’t rely on it to get me somewhere I’d never been, but the developers even say it’s meant to assist you in driving a route you regularly drive such as your commute to work. It’s really good at showing heavy traffic, and alerting you to it. When I’ve gotten stuck, it automatically notices I’m going slower than the speed limit and updates the map. It’s a shame that more people aren’t using it.

Oh, and it’s FREE, for iphone, android, and windows phones.

Pretty neat if you ask me, next crowd sourced augmented reality.

I’m not sure if those mis-information maps have ever been released and analyzed, does anybody know?

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In the same issue someone also talks about Buffon’s Needle Problem which is worth reading about.

LTSpice – Free As In Beer

November 13th, 2009 by noise

LTSpice is a free SPICE simulation tool from Linear Technologies.

For those in the electronics world, SPICE simulation can be a great way to answer the “will my circuit work as advertised” question without breadboarding. It’s a great sanity check- if it don’t work in SPICE, it won’t* work on a breadboard.

LTSpice is Linear Technologies’ own incarnation of SPICE. It’s a nice little product, and comes with models for many of Linear’s products (power supplies, op-amps, etc) along with many supporting components from other manufacturers (diodes, transistors, capacitors, inductors, etc) and generic parts (555s, LEDs, etc). Obviously, they provide it expecting people to download it, sim up a solution involving Linear parts and then sell eleventy-billion a year, thus providing a nice income stream for Linear (and it works- LTSpice makes it much more likely that I’ll reach for a Linear part for power supply design than another manufacturer’s parts).

[via uptownmaker]

Business Meeting, Wed Nov 11, 7pm

November 10th, 2009 by noise

tcmaker_meeting

Twin Cities Maker is having a business meeting, Wednesday November 11 at 7pm.  As usual, our meeting will be in the back room at Common Roots Cafe, 26th and Lyndale, Minneapolis. Topics for discussion:

  • Maker Faire Attendee Ideas – Please come to the meeting with at least two ideas for groups or individuals that could be invited to a Maker Faire.
  • TGIMBOEJ Collection – Bring any electronics junk that you would like to contribute to The Giant Internet Migratory Box of Electronic Junk.
  • Halloween Event Report
  • Prototyper Build Update
  • Financial Update
  • Vote for Secretary
  • Grants
  • Officer reports
  • AOB

Hope to see you there!

Rapid Prototyper (aka Flutterwumper) Build Session (Sat. 11/7 2pm)

November 5th, 2009 by uptownmaker

flutter

There’s been a lull (partly due to my becoming a parent, partly due to summertime/school opening blues) in work on the rapid prototyping system. It turns out that this was a blessing in disguise because I recently got my hands on something that will make this project a significantly different scope.

My company threw out an old solder paste inspection machine. It WAS a machine intended for use inspect printed circuit boards after they’ve had the solder paste applied to them but before they’ve had components placed. As far as I know, it is in full working order.

Before. After. The first accessory.

In short, this is a working X-Y gantry with sub-millimeter accuracy. It does have SOME Z motion, too, but not much- I’d guess in the end we can adjust the limits and get something along the order of one inch in Z.

For a platform to build a prototyper, you can’t get much better than this. And it’s in my garage.

See the forum thread for further details or schedule changes.

Stereophotography

November 4th, 2009 by bobble

A couple of years ago I got into making stereograms. I saw it in a how-to book and thought that it was pretty cool! I didn’t realize just how easy it is to create stereograms. All you have to do is take two photos about 3-inches apart and use software to merge the right/left images together.

Cross your eyes to view it.

Taking the Photos
with a single camera, you are limited to taking static pictures. There can’t be any moving objects; cars, blowing trees, flying mommy-bombs, etc. if you look closely in the above stereogram, something had moved near the foundry. It was a windy day. It creates a double image which you don’t notice right away but then try focusing on it.

Get about 6-8 feet from your subject and take one picture. Shift your hips to the left or right a couple inches while keeping the camera steady. Keep the lens parallel to the first shot. Take the second picture.

One In Thirty Rule
the distance you move, or lens separation, is called the stereo-base. In order to take decent stereo photos, distance to the nearest subject should be approximately 30 times the stereo-base distance. This is called the “one-in-thirty rule”. Our eyes are about 3 inches apart. This would mean that the nearest subject should be roughly 8 feet away.

Software
I use Stereo Photo Maker (click here) to create stereograms. It has functions to help correct alignment problems. Almost every stereo pair I’ve taken has alignment issues. I might’ve tilted the camera or moved it vertically too much from the first snapshot. This software will help make it more goodly. I’ve built a tripod mount for sliding a camera back and forth. I found that just shifting your hips, keeping the camera steady, and using this software is good enough… you won’t notice the difference.

Viewing Stereograms Without a Viewer
Bobble no like anaglyph 3D pictures. It’s those 3D pictures where you need red/cyan glasses to view them. The colors get all messed up. I prefer “freeviewing” without glasses or viewer. There are two ways of freeviewing stereograms. It depends on how the images were joined together. If the right eye image is on left-hand side of the stereogram then you need to cross your eyes to view the image. The size of the photos are quite large, I think its best to use cross-eyed viewing.

If the right eye image is on the right-hand side of the stereogram, then you don’t cross your eyes. You stare past or through the plane of the image. When you do this correctly each eye will see its intended image. This is called parallel viewing and for some people it’s a little harder to master.

In both methods you’ll end up seeing a third image that appears between the two photos (called the cyclopean image). That’s where you focus your attention. Eventually your brain locks in on this virtual image and then things start to stand out.

Some people have difficulty seeing 3d stereograms. It’s not unheard of for people to get headaches. I recently ran into my own problems and had an eye cataract removed. Now the only way I can freeview is if I’m wearing a contact lens in my good eye and wearing reading glasses. Sucks to be me.

What’s strange is if you accidentally swap the images or cross your eyes at a stereogram that is meant for parallel viewing. The cyclopean view looks 3d-ish but in a weird way like the image is inside out. When in doubt, try parallel and cross-eyed viewing to see what looks correct.

Some Guidelines
when taking stereograms photos:
* Everything in the picture should be in focus.
* The depth of focus should be large as possible.
* Avoid dark backgrounds
* Avoid excessive moving subjects like blowing trees or clouds.
* Follow the one-in-thirty rule.
* Keep the cameras level to the ground. Avoid tilting.

Stereo Camera Rig in Stereo!


Another cross-eyed stereogram. It’s a little easier if you have two cameras and rigged them with a dual trigger mechanism. Yes? Yes!

Dig the BMX bike peg for the handle! And toggle switches!?!

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