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tablet time

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switching it up.

Powering up the new lightning solution!  Requirements:  clear mount [check], no dock connector[check], powered by 12 volt rails [check]!

"hard pressed..."

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photo by Liz Hafalia for the SF chronicle

Julian Guthrie wrote a very nice chronicle article about my role within the CAS avee department, and more specifically, my involvement in the snow machine automation.
Here's a PDF as well:  snow_article_tosh.pdf

Cycling '74 (creators of max/msp) asked for a bit more here, and here is the original imlichent post!
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artpad sf

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yup, their filling a hotel with art.

i just wanna hold your hand  will be holding down the lobby/bar thanks to gaffta!

Here's a link to the ijwhyh instructables!

EDIT:  video from opening night!

7-segmented display install (pt2)

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almost pi!

Here's the finished product.  The orange fountain is made by global tap, and designed by Ideo.  The electronics, and signage are in-house.

the board with the displays (yes, there's a rework wire!):

And the original post with video!

...eventually, these lights program you!

A max/msp project listing has been created here.  It gives a quickie description of how the attraction works.  The LED's pictured above are what illuminate the 1989 and 1906 alamo square skyline.  However, the photo does not give justice to their intensity.  I oft found myself siren-eyed from watching them pulsate!

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exhibit tremor control

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"looks different at night?"

So its over.  Everything is installed, everything works, and works pretty well!  It felt like winning tetris.  The team came together and crafted custom code, hardware, audio, lighting effects, parallelograms & trapezoids--so much stuff!  Time to rest now :)

a revision 1 of a capacitive touch board.

the shakehouse exit portal where much of my time was spent.

developing on a 42" monitor at my bench...

2.3" 7-Segmented Display Prototype

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wire crazy?

This is a 7 digit, 7-segmented display, utilizing several TL constant sink drivers, and the parallax propeller 32 bit, 8-core MCU.  There's a TL driver for every common anode digit; communication is handled via SPI to the cascaded shift registers.  The prototype is 100% wire wrapped, and surprisingly fast!  

Originally we looked into using the maxim 7219, which was a single IC to drive all the segments.  That particular IC is limited to 5v and something like a 60ma sink, which would never drive the 14.4 v, 100ma segments!  There is a way to do it, but the transistor array and/or auxiliary maxim IC's required felt component heavy.  One fun note on the 7219:  it works on POV!

The Propeller MCU was chosen arbitrarily; another project will require these chipsets, so it seemed like a good idea to brush up on 'em.  They are very reliable and incredibly versatile;  parallax sells a kit to make videogame systems out of them!  The compiler crashed on XP, but worked fine on windows 7.  The language itself, is a bit clunky, but the 8 "cogs", and 80mhz speed make up for it!

Lastly, this device will count waterflow, but only once the PCB is back!


Installed and operating, this device is live!  It only needs a darker tint on the glass.
Here's some ktsf video with it.

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Glass as Speaker Cone

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"thanks bob!"

In college, there was a professor who well, taught me that you can do anything, but you need to do it yourself--specifically with electronics and audio.  Anyhow, one day he took an induction driver (pretty much a speaker without a cone), and turned a wall into a speaker.  Many years later, I was reminded of Bob Bielecki's demonstration (all of them really), and decided it would be a nice solution for an upcoming project:  transmitting audio through glass!  Displayed here is a proof of concept mock-up, with gaffers tape holding the driver on instead of cold-weld adhesive.  Eagle eyes might spot a Programmable Logic Controller, a PIR, and a solid-state audio repeater/amplifier.

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Plenty of Flux, tons of Capacitors

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"where's the device to speed up or slow down the passage of time!?"

godzilla & the elasmosaurus as time travelers.

This one is quick and neat:  charged with changing clock speeds.  For some reason I always figured that analog clocks had little dc, pager-type motors in them.  I was proved wrong.  The quartz-clocked copper coil is pulsed at regular intervals, turning something akin to a miniature top.  This "top" is the rightmost gear; teeth on top, magnet on the bottom.  The coil itself has a "fork" which surrounds the +/- poles of the top, therein turning it without touching it.  This near frictionless drive is why this motor lasts so long and so reliably!

However, it was designed to run at a certain speed.  So there are certain speeds that the gearbox rejects, and others that ring true.  These "usable" speeds were found by hooking up a function generator to the coil.  The rest was done with a 555 generated pulse, which was rigged to run at the "happy" speeds.  So in effect, we're bypassing the very regular crystal oscillator with the 555.

^^a giant 555 footstool! source:evilmadscientist

And in case you don't have the most endearing 555 source ever, here it is!:

Forrest Mims is a personal hero, so buy the book if you get the chance; it's better on pulp.

thats it for now!
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electric eel et. all

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Unfortunately, its not ours.  In a previous era, we had an exhibit which translated the EEL's output current to an audible pulse, which the public could hear.  Of course, those days are gone... 

Currently, there's a hacked TEN's machine which provides a light jolt to the public.  Sadly, its a complete hack-crack job-- dangerous perhaps to work on, and not made by our hands!?  There have been enough complaints concerning a low level of jolt.  There is one main problem: each user has a different electrical resistance.  What is normal?  Even upon measuring one's self (thumb to forefinger), you can get anything from 40k ohm, to 4m ohm (ahem, based on my own)!  

There is one main problem: each user has a different electrical resistance.  What is normal?  Even upon measuring one's self (thumb to forefinger), you can get anything from 40k ohm, to 4m ohm (ahem, based on my own)!  

So the question is, at what strength do we make the eel v2 circuit at:  40 volts, 60 volts, 160 volts!??  How moist will the users hands be?  With what surface area & pressure will each user touch the probes?  Will The users go directly from the salt-water touch-tidepool to the exhibit!!??  Well, obviously, we just need to guestamate this one...

As of of now, it's a coil based unit utilizing an npn TV cathode deflection transistor.  Its under stress testing right now.  The first crack had problems with thermal runaway i.e. everything would work perfectly for half an hour, until one under-spec'd capacitor would overheat and pull current. anyhow, thats the update!


Well, it survived the week long bench test, so now its installed.  Currently we're running a set-point of 176 volts! 

UPDATE 3 still has electric appeal.
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