On Theo Jansen’s walking mechanism…

If you haven’t heard of Theo Jansen and his incredible walking machines, I can’t do them justice with words. Check this out:

His work is accessible from strandbeest.com. I find his creations amazingly cool.

And others do as well, even hamsters (although cats seem less impressed):

But while I’ve found these things fascinating, I didn’t spend a lot of time researching the exact mechanism, nor thought about fabricating my own. And now I don’t need to!

Check out this awesome link to get code to design variants, visualize them, and even OpenSCAD source code go generate actual 3d printed models. That’s just too cool.

Batsocks – Text on TV – Introduction

The chaps over at the Batsocks blog sell a cute little gadget called the “Tellymate”: a nice little serial->video converter that is very, very simple. It uses a single Atmel AVR Mega, and handful of other extra components to implement a full character mapped 38×25 character display terminal which reads characters from a serial input port. But what’s really great is that they have all sorts of good information on how the gadget actually works, meaning that you can adapt the techniques and ideas for your own use. Very cool.

Batsocks – Text on TV – Introduction.

The interesting bit that the Tellymate implements is a higher density display than can be achieved with the arduino TV-out library that I mentioned a few days ago. It does this by leveraging the SPI output to automatically clock out bits 9 at a time, which gives you enough time to actually stream out 38 characters (about double what I can achieve with the Arduino library). Very neat, but there are some details which are a bit crufty. Lots of good information.

Old Glory, in Postscript

I needed a graphic of a flag that I could scale to whatever size I needed. About 10 minutes of Postscript hacking with the specifications in Wikipedia yielded the following results:

Sadly, the syntax highlighter that I have here doesn’t know about PostScript, so I’ll just have to add it here.

% PostScript program for generating an image of the US Flag
% Generated by implementing the specifications which are listed on
% the wikipedia page:
% http://en.wikipedia.org/wiki/Flag_of_the_United_States#Specifications
% by Mark VandeWettering

/inch {72 mul} def

/Hoist 1.0 def
/Fly 1.9 def
/UnionHoist Hoist 7 mul 13 div def
/UnionFly Fly 2 mul 5 div def
/WidthStripe Hoist 13 div def
/F 0.054 def
/G 0.063 def

/StarDiameter 0.0616 def
/StarRadius StarDiameter 2 div def

% When a regular pentagon is inscribed in a circle with radius R, its
% edge length t is given by the expression:
% t = 2 R sin(pi / 5)
% PostScript does sin in degrees, so we need 180 instead...

/StarSide StarDiameter 36 sin mul def
/StarDiagonal StarSide 5 sqrt 1 add 2 div mul def

/white {1 1 1 setrgbcolor} def 
/red {0.698 .132 .203 setrgbcolor} def
/blue {0.234 0.233 0.430 setrgbcolor} def

% draw a star at the cursor position...

/stardiagonal {
	StarDiagonal 0 lineto
	currentpoint translate 
	-144 rotate
} def

/star {
	exch StarDiagonal 2 div sub exch 
	StarRadius 18 sin mul add
	moveto currentpoint translate
	4 { stardiagonal } repeat closepath
} def

% draw the border...
/Flag {
    0.001 setlinewidth
    Fly 2 div neg Hoist 2 div neg translate
    0 0 Fly Hoist rectstroke
    % paint in the bg, just in case
    0 0 Fly Hoist rectfill
    % paint in the red stripes...
    1 2 13 { 
	1 sub
	WidthStripe mul 0 exch Fly WidthStripe rectfill
    } for
    % draw in the union...
    0 Hoist UnionHoist sub UnionFly UnionHoist rectfill

    % now, the stars, easiest to do in two passes.
    0 Hoist UnionHoist sub translate
    1 2 9 {
	/y exch def
	1 2 11 {
	    /x exch def
	    x G mul y F mul star
	} for
    } for 
    2 2 8 {
	/y exch def
	2 2 10 {
	    /x exch def
	    x G mul y F mul star
	} for
    } for 


} def

8.5 inch 2 div 11.0 inch 2 div translate 4 inch dup scale





Oh, incidently, you can use The Gimp to convert this from PostScript to a normal graphics format like the PNG file above. It will even do some antialiasing to make the jaggies look better. Very nice.

Making a soft-circuit input device for your computer

I’m intrigued by various uses for embedded processors, and so are my readers. I hadn’t seen this particular microcontroller board before, the “Teensy”, which is very similar to the Arduino, except that it is uses an ATMEL AVR chip with a direct support for USB. The link also points at a nifty interface to “soft circuit” elements, which probably has some nifty controller applications.

Make: Online : Making a soft-circuit input device for your computer.

A New Podcast! With Reviews of XM Radio and the Panasonic DMC-TZ1

What can I say? I was bored on the way home yesterday, and decided to record a 23 minute podcast, reviewing two of my moderately recent gadget purchases:

I also gave a brief report about my trip down to the Computer History Museum to see their recently restored PDP-1 and play Spacewar!

And I shamelessly plug Pixar’s upcoming summer release of  Cars.

I still get pinged by lots of podcast aggregators, here is hoping that somebody is listening.

little tips about making rc micro_helicopter

It’s been a busy week for me, wading through piles of SIGGRAPH sketch reviews, so I haven’t had too much inclination to spend more time in front of a computer.   But I did find this article linked on the make blog: little tips about making rc micro_helicopter.  A very cool micro helicopter, which used a CDROM drive motor for the main drive.  Very cool.

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Alcohol Breath Test Pen

The Only Pen a Drunk Could Ask For – Gizmodo

So you’re at your favorite sports bar watching the big game with your friends. Before heading out and driving home, perhaps it’d be a good idea to make sure you’re not legally intoxicated. At this point, it’s just a matter of whipping out the Alcohol Breath Test Pen, blowing into the top and hoping that the green LED doesn’t turn red. If it’s red, hail a taxi, buddy, because you’re in no condition to drive. Also included in the pen is a UV indicator, letting you know whether or not you should be wearing sunscreen. Yes, this $35 little pen can help save your life and prevent a nasty sunburn.

What you really need is such a pen which prevents you from writing checks, signing contracts, or most importantly, posting to your blog when drunk.

Lay Siege to Your Enemies!


Feel the need to lob tennis balls at those who oppose you? Try checking out these rather nice plans for a small trebuchet. With such a mighty seige engine, none dare oppose your military might!

Seriously though, these things are:

  • interesting mechanical devices
  • fun to play with
  • and excellent for tossing water balloons.

Unless of course, you get hurt, in which case you didn’t hear it from me.

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My new PC…

Over the last couple of months, I had gradually decreased the number of computers in my office to just two (well, computers that have X86 architecture anyway), and I decided that I would like to have a new amd64 based machine. I priced out the cost of just building one from components, and found that I probably couldn’t do better than the HP a1310n, so I just went out and bought one. I’ve purged the windows infestation off it, and installed Fedora Core 4 on it. I’ve got a number of projects that can benefit from its high speed, including goofing around with MythTV and Asterisk. I got the ivtv driver working on my WinTV PVR150 MCE card and even have accelerated X running on it, so progress is being made. Last night I had some difficulty with Asterisk, the ztdummy driver that provides timing information seems not to load for reasons that escape me. But the hardware seems to be quite nice, I only wish the onboard video had NTSC outs, then this machine would be ideal as a front end for MythTV.

Downgrading my Axim X50v

Well, I spent $40 for the Windows Mobile 5 upgrade for my Dell, and it’s been a pain in the ass ever since.  Apparently I’m not alone, since now Dell officially lists a downgrade for the Axim: yep, it’s back to 2003 SE for the little guy.  Maybe it will stop blinking its stupid LED, draining its battery, and just being a pain in the butt.

Click here for the downgrade.

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Sony Thwarted Again – PSP 2.60 Hacked – First Homebrew Emerges!

I saw this on digg this morning:

A hacker has taken the next step and accomplished the unthinkable, hacking the 2.60 Firmware PSP! It is now possible to play homebrew games on your PSP no matter what firmware it has. Sony, give up on trying to stop us!

I haven’t tried this out yet (the new is still on my PSP, and I don’t feel like screwing it up) but it seems silly to actively pursue a strategy of trying to keep your customers from using their machines in creative new ways. I wish that a console or handheld manufacturer would someday realize that by embracing user modifications and homebrew, they could potentially add value to their products.

I know, I know, they are trying to prevent piracy. They don’t want everyone to be running Wipeout Pure when they didn’t pay for it. I get that. And I must admit, I don’t really know how to establish an iron-clad piracy protection scheme, but then, neither does Sony (obviously). I was thinking the other day that it might be interesting to have programs which are executed from the Memory Stick to simply not be able to access any of the Disk hardware. I can think of lots of ways that might fail, and hardware mods might still work to circumvent such measures, but it would go along way to keeping people from snarfing data off of UMD disks.

Of course, if anyone DOES get it off disc (say by using a logic analyzer on the data bus during execution) you are screwed.

Oh well. I imagine that we’ll see a continuation of this arms race for some time to come.

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