Monday, December 29, 2008

Dorkbot SoCal Jan. 10 - Aschheimm, Evans, Guttman

Saturday, January 10, 2009
Machine Project
1200 D North Alvarado Street
Los Angeles, CA 90026

Presenters will include:

Deborah Aschheim

Deborah Aschheim creates works that blur biology and technology, exploring concepts of memory, architecture, and neural networks through drawings, sculpture, writing, installation and sounds.

Brian Evans

Brian Evans explores the intersection between reductivist sculptural form and the aesthetics of behavior, where structure and thought are fused.  He creates simple moving objects with seemingly life-like qualities - electromechanical life forms with motivations only just beyon our understanding.

David Guttman

David Guttman creates interactive works that generate unique colors and shapes from sound and EEG.

Thursday, December 25, 2008

Stacking Arduino Shields

So what if you need two shields on your Arduino?  Try using wire wrap sockets.  The wire wrap bit will fit into the socket below (snugly), and the socket bit will serve as a socket for the next shield up.

From Digikey, I picked up two SAM1125-06-ND (CONN RCPT .100" 6POS TIN WW) and two SAM1125-08-ND (CONN RCPT .100" 8POS TIN WW) to replace the standard header pins in a SparkFun Protoshield.  That is where I will be placing the support circuitry for the "Breath" project.  On top I will have a LadyAda Ethernet Shield.

Here are the results:

Protoshield with wire wrap sockets

Protoshield with wire wrap sockets

Arduino, Protoshield, and Ethernet shield

Arduino, Protoshield, and Ethernet shield

Monday, December 15, 2008

Anemometer Impellers

I saw some Kestrel replacement anemometer impellers for a reasonable price, and thought they might be good for the "input" section of my breath-over-IP project.  PC case fans turn better when "gutted" of their coils, but you still have to blow pretty hard to make them move.  The replacement impellers brought the promise of spinning under exceedingly low air speeds because of their jeweled bearings.

So the good news:  The replacement impellers do spin very easily.  The lightest breeze your mouth can produce will spin them.  Perhaps they are even too sensitive, as just moving the impeller will make the blades move.

The surprise:  They are really small - from left to right is the case fan, the impeller, and a quarter:


My Radio Shack IR emitter/detector pair were going to be too big & bright for the job, so I went to Fry's and picked up an NTE3029B IR emitter and the matched NTE3034A phototransistor.  These devices are small, side-looking devices with integrated lenses and are much more appropriate for the job with the small impeller.


Here is the Kestrel impeller as a "breath input" using an Arduino and a case fan "breath output":

According to the Nielsen-Kellerman patent, there actually is a little magnet in the impeller somewhere which might be able to sensed with the proper sensor.  I am considering getting a Hall Effect sensor and trying it out, but at least I know the IR scheme works.

Wednesday, December 10, 2008

Opto-interrupters for Breath

Recap:  "Breath" is a breath-over-IP phy2phy system.  You blow on one fan (anemometer, whatever you want to call it), that data is sent over IP to the other side where a fan it turned on to match how strong you are blowing on it.  It was inspired to some extend by Scott Snibbe's "Blow Up".

At first I thought I'd do a "half-duplex" solution with a single fan being both the anemometer and the powered fan.  Unfortunately, it takes a lot of wind to blow a case fan around.  I discovered that if you take the coils out of a fan, it spins much easier!  Which lead me to a "full-duplex" solution of one gutted fan as an anemometer, and another as the actual fan.

To measure the anemometer, I started out with an NTE3100 slot-type opto-interruptor, using a piece of aluminum from a can to slide through the slot:

Using a slot-style opto-interrupter

This had the advantage that the NTE3100 available at Fry's.  The disadvantage was that the aluminum bit takes up excess space and could get bent.

We all know that Radio Shack isn't what it used to be, but guess what, they still carry 276-142 "Matched IR Emitter and Phototransistor".  So I mocked them up on a breadboard with the Arduino to ensure it was dependably reading over the distance required:

IR Emitter, Detector, and Arduino

IR Emitter (looks blue to camera)

IR Emitter detector pair and fan

Next step:  I need to get another NTE2987 (N-ch, logic level FET) from Fry's.  I also need wire wrap sockets from Fry's so that I can stick an Arduino ProtoShield in between the Arduino and the Ethernet Shield.  Then just solder it all together and do the software!

Also I may move up from a gutted fan to a real anemometer impeller (with jewel bearings, etc.)