scruffy days

So we’ve superglued our salad spinner to our servo & running the 4 leads through 2 sets of rectifying diodes:

Voltage & Current Readings:
Slow, full tug - up to 50mA, 5V
Increase speed - about 100mA, 10V
More force & speed - up to 180mA, 12-18V

These are all maximum values, so they only reach these when the spinner cord is drawn to its fullest length. See how the voltage values spike in this video

Added 1F 5.5V capacitor to circuit (had about .5V left from experimenting with it yesterday). After a couple tugs, reading at 1.02V. After 10 medium tugs, voltage up to 1.96V. Tried carefully not exceed the 5.5V reading so as not to damage the capacitor, but even as I increase force, it’s more difficult to get past 3.5 or 4V. Cap now at 2.71V. Plugged in LED, charge started immediately dropping. Within about 20 seconds, reading of cap went down to 1.93V, and continuing to trickle out with the LED acting as a load to drain the charge. In the case of the shake lights, a switch is used to allow the flow of electricity to the lights. Is that how we should control the flow in this case? Can we prevent/control the trickle with just a switch?

Next step: Read datasheet on Fast Charge IC Management chip, bq2000 (available as free sample from Texas Instruments). “A programmable IC for fast charge management of NiCD, NiMH, or Li-Ion in single applications. The bq detects the battery chemistry and proceeds with the optimal charging and termination algorithms.” Whoa! what algorithms? Ahem, let me continue: “This process eliminates undesirable undercharged or overcharged conditions and allows accurate and safe termination of fastcharge.” Sounds promising…setup below still needs to be tested:

Bought a charger, 2 AA Ni-MH rechargeable batteries and a battery holder from Radioshack. Specs on packaging note the charging current:
140mA +-10% for AAs
80mA +-10% for AAAs

Just a quick update - ran Tom’s Processing code to check on the mesh network - yay! the battery is still alive. Reading coming in at 1PM today (38 degrees F, cloudy) is 582, so we divide that value by 44.22 to get voltage reading of 13.16, which Gilad confirmed with a multimeter reading off the 12th floor controller. Here’s a screenshot:

Gilad and I continued working on RoofLink, a network of XBee radios for datalogging voltage readings from ITP’s solar panel. The problem we ran into last semester was keeping a steady supply of power to the XBee circuit on the 8th floor. For reference, here’s the original diagram again. But now, with the firmware upgrade to the radios, no PIC chips are necessary, and we’re powering the 12th floor circuit directly off the solar panel’s leads. This way, when the sun goes down, the circuit is turned “off” and the 8th floor XBee can get a good night’s sleep. Perfect, since there’s no data to log then anyway.

XBees consume 3.3V and 10mA (with no LEDs) in their “awake” operational state. With LED indicators for power, sending and receiving, they use 60mA.

MaxStream has a great app for configuring and testing the XBees, X-CTU, which you can download here (Windows only). This made adjusting the settings so much easier than when we were using Terminal/Screen and typing in AT Commands. That was much more tedious, and you’d only have a short window of time to enter new commands after the +++. Here’s a nice screenshot courtesy of Faludi. Also gives you details on commands and settings.

Tom guided us on using X-CTU’s handy features, and how to eliminate the PICs. Here are most of the settings:

Under ‘Modem Configuration’, select Always Update Firmware and Version 10A2.

#0 (12th Floor)
MY 0
DL 1
IR 17 (Sample rate)
IU 1
IT 5

#1 (8th Floor)
MY 1
DL 2
SM 4 (Cyclic sleep mode)
SP 214 (Cyclic sleep period)
ST 30 (Time before sleep)
GT 40 (Guard time)
DP 3E8
IU 1
IT 1

#2 (4th Floor)
MY 2
Will note other settings soon…

During testing, we used a DC Bench Power Supply to act as the solar panel. Got a Processing reading of 446 when feeding circuit 10V, but we’ll test other values to get the most accurate translation for datalogging.

Notes on Sleepy Time:
We tried a few approaches in sleeping the 8th Floor XBee. With Sleep Mode 5? (gotta double check this), we couldn’t wake the sucker up - had to manually reset the radio and exit out of that mode. Then we also tried this example from MaxStream, requiring a Coordinator/Remote relationship, but this wasn’t successful for us either. Eventually, it appeared to be a balance of timing between #0’s IR and #1’s SP and ST settings, with #1 set to Cyclic Sleep Mode. If #0 sent samples too fast, #1 would never have a chance to sleep; but on the other hand, if too slow, #1 wouldn’t catch any packets and keep returning to sleep. With current settings, readings come through every 15-16 seconds.

Amperage Measurements:
XBee #0
regular 6.0 mA
no LEDs 10mA
XBee #1
Cyclic sleep 24.5mA
Cyclic sleep, no LEDs 0.17 mA, with 2.16mA “burst” during sending of data

XPort Notes:
For the XPort on the 4th Floor circuit, updated Connect Mode from D4 to C4 (need to note why here). This was done just by telneting into the XPort’s IP address via Terminal and using port 9999. No need to do any of that hardware setup like when you initially configured these - takes you direct into Setup.

TO DO:

1. Review incoming values and adjust code
2. Update PHP script for datalogging, add Cron Job
3. Measure 9V battery life (new battery placed around 1:30am 1/31/07)

#0 - 12th Floor Circuit. Using Sparkfun FT232 for configuration

Setup with DC Bench Power Supply, and testing packet sending with Processing app from Tom Igoe

#0 - 12th Floor Circuit, with “resistor tree” enclosed in shrinkwrap tubing (just to have less exposed components)

#1 - 8th Floor Circuit. When sleeping, the green LEDs blip periodically. Yellow LED indicates both sleep and receiving of data.

Screenshot of data parsing using Tom’s PHP socky script, with some javascript data viz from David Nolen. Clearly, we’ve still got some tweaking of our readings to take care of. To be continued…

Using a hacked stepper motor from a junked printer and a salad spinner to convert kinetic energy to small amounts of electricity. This initial test produced a max of 6V and 40mA, but the setup is just quickly hacked together. A more stable setup should yield better results. The motion of pulling the drawstring is fun & playful - Megan and I are still brainstorming on possible uses for the converted energy. Check her notes for more documentation.

The theme of sensing visitors’ presence and colors is a topic a number of ITP projects touch on. The scale of it is visually interesting, but the response left us a bit disappointed. It wasn’t clear at first where you had to position yourself for the installation to react to your presence. We eventually saw the iSight, and even waved Tikva’s red jacket in front of it, but still the color shift was really subtle, and the faint pink hue slowly traveled up through the rest of the LED tiles.

But it made me think about why these types of pieces are still fascinating - we like to affect changes in our environment, and people are drawn to visually responsive/mirror like pieces. We like gadgets and technologies that DO things for us, respond to our touch, get info for us, tell us where we are, show a trace of where we’ve been… Danny Rozin’s mirrors and similar camera sensing/abstract mirroring projects are so appealing, I think, because you see yourself in another form, you affect change in this particular piece, and for a moment you are the main focus and actor in this piece. You actively become part of the project itself. What was missing from this installation seemed to be how limited where you had to be in order to become part of this experience. It would’ve been more fun to see how my colors could meet/mesh/clash with someone else’s and what that could imply. But maybe it just wasn’t working properly when we visited, since these Gothamist pics depict an entirely different experience.

Visited the Griffith Observatory with my parents during my stay in L.A. Here’s the view at night.

A work in progress, but now provides some organized documentation on the project - gardenelectric.com

Yay! We made it!

Garden Electric came together in the nick of time - phew! We ended up modifying the layout on day 2 to fix the issue of air traveling upstream. The synchronized action of the bellows stole the show from our precious plastic flowers. Good feedback, kids loved it and we never tired of the Garden’s quirky, hilarious performance.

So many brilliant projects - wish I could’ve seen them all. Check out ITP Vlog & rocketboom for additional coverage of the show’s goods.

it’s 2:53am.

“first rule of the show is you don’t talk about the show…”