Food in the City and Subirrigation

24 Feb

I was recently invited by Shaunalynn of sprout & co to speak at the Food in the City Spaghetti Dinner about my experience with subirrigated gardening.  Subirrigated gardening is a way of growing plants that conserves water, preserves fertilizer, and simplifies watering.  I regularly consult the Inside Urban Green blog for information on subirrigation which is authored by Bob Hyland, founder of the Center for Urban Greenscaping and the definitive subirrigation guru.  Other topics for the evening included raising chickens, Sam Katz-Christy on his Somerville yogurt co-op, Tai Dinnan from Groundwork Somerville on maple tree tapping and syrup making, and Mike Nagle on window farming in urban areas.  Live illustrations were created by Isaac Bell during the talks which reflected the topics at hand.

I’ve been interested in making my own yogurt for some time now and learned a lot about the process as Sam fielded an array of questions from the crowd.  The co-op operates from the industrial kitchen of the Clarendon Hill Presbyterian Church and sources milk regionally from Crescent Ridge Dairy. Crescent Ridge Dairy delivers in glass containers which helps reduce plastic waste when making yogurt in large batches;  Sam’s simultaneous consideration for the environment and community was inspiring.

Sam Katz-Christy fields questions about yogurt making and running a co-op.  Photo by Meaghan Boyle.

Sam Katz-Christy fields questions about yogurt making and running a co-op. Photo by Meaghan Boyle.

My talk reviewed the principles of subirrigation including 2-liter soda bottle designs and larger planter designs based on corrugated drain pipe which are more suitable for growing vegetables.  The planter below was built from a 3-liter bottle and housed a couple of happy basil plants.  Herbs do very well in these 2 and 3 liter designs.

A 3-Liter planter that I built to grow basil.  Photo by Meaghan Boyle.

A 3-Liter planter that I built to grow basil. Photo by Meaghan Boyle.

For growing tomatoes and peppers, the corrugated pipe planter designs are the easiest and most reliable to build.  Below is a section of the corrugated and perforated pipe cut to fit in the bottom of the clear container shown to the right of me.  I would use this planter to grow one tomato plant or two pepper plants.  Clear containers allow you to observe water levels without detriment to the plant.

Showing off corrugated and perforated drain pipe for building planters.  Photo by Meaghan Boyle.

Showing off corrugated and perforated drain pipe for building planters. Photo by Meaghan Boyle.

There was a great turnout for the talks.  The picture below by Chris Connors shows a small fragment of the assembled crowd;  I really enjoy hanging out after talks at hackerspaces to meet new people with similar interests.

The crowd at Sprout as well as live artwork being projected behind me.  Photo by Chris Connors.

The crowd at Sprout as well as live artwork being projected behind me. Photo by Chris Connors.

I am working on finishing a Make Project page which will include details on fertilizer, pesticide, and other concerns.  For more information on subirrigation I highly recommend the Inside Urban Green Blog as well as the EarthBox Forum.  Now is the time to order and start your tomato seeds for the upcoming season!

If you’d like to stay in touch with sub-irrigators in Somerville, MA and Boston, join the Sub-irrigate Sprout google group.

Hawaiian Sweet Bread with Laser Cut Flour Stamp

10 Feb

I’ve been working on a technique to use flour to stamp breads with laser cut designs and  have finally found a technique that works acceptably well for intricate patterns.  The breads below were made with this Hawaiian Sweet Bread recipe.  Here is the result after baking:

Finished Loaves with Flower of Life Flour Stamps

Finished Loaves with Flower of Life Flour Stamps

The pattern I chose is called the Flower of Life.  It is a six-fold symmetry made with overlapping circles.  Here is a video of the cardboard stamp being cut:

Once you have a cardboard stamp, you can moisten it with water to curve it slightly to fit the loaves.  I did this by using a rubber band placed around the pattern and a can of corn meal.  About 10 minutes before baking, while the oven is preheating, use a spray bottle with water to wet both the slightly curved pattern and the bread.  Shake flour over the wet side of the laser cut cardboard pattern.  Apply the pattern flour side down and press gently.  Here is a picture of the flour coated wet cardboard being applied to the moistened bread.

Flour stamp being applied to a bread

Flour stamp being applied to a bread

If you’re careful, it should look like this before putting it in the oven:

Bread Stamped with Flour Ready for Baking

Bread Stamped with Flour Ready for Baking

I’ve heard that rice flour mixed with normal flour improves the outcome.  You can also create these patterns with an X-acto knife in cardboard to achieve the same effect.  Have fun tagging your loaves of bread!

Dorkbot Boston and Lawrence Lessig on Institutional Corruption

8 Feb

Tonight I attended the first Dorkbot Boston meetup of 2011 hosted at Sprout in Somerville, MA.  Dorkbot is a monthly meeting of artists, designers, engineers, students, scientists, and other interested parties that is free and open to the public (check to see if there are local Dorkbot meetups near you) .  Tonight’s meetup, the first in a while, was a resounding success with roughly 30 people facing icy winds to attend.  A featured guest was Brian Whitman who spoke on the evolution of Dorkbot and his company, The Echo Nest.  The evening was hosted by Adam Hasler who has recently taken over as the Boston organizer.

Adam Hasler hosted Dorkbot Boston at Sprout

Adam Hasler hosting Dorkbot Boston at Sprout

For those who are unfamiliar with Dorkbot, one of the cooler aspects for me is Open Dork where anyone is encouraged to speak about a current project for a short time.  This encourages collaboration and community building in a very small amount of time.  For example, I learned about the New England Model Engineering Society in Waltham, a new hackerspace in Lowell called MakeItLabs (they will soon have a lasercutter), and had a chance to meet several local and visiting geeks (from as far as Portland, OR).

Open Dork allows anyone to present current projects and upcoming events

Open Dork allows anyone to present current projects and upcoming events

Yesterday, I had the pleasure of attending a talk by Lawrence Lessig on Institutional Corruption, a core topic studied by The Lab at Harvard’s Edmond J. Safra Center for Ethics.  The talk focused on the institutional corruption of congress and lobbying.

Lawrence Lessig presents on Institutional Corruption

Lawrence Lessig fields questions regarding his Institutional Corruption presentation

You can view the same Institutional Corruption – Short Version presentation online.

Soil Moisture Meter with a 555 Timer

5 Feb

For the past two days, I have been thinking about and building a low-cost electronic soil moisture meter for house plants that does not involve using a microcontroller.  To accomplish this, I envisioned being able to blink a light (LED) to indicate when a plant requires water using a cheap 555 timer and two nails to measure soil resistance.

Soil Moisture Sensor based on 555 Timer

Soil Moisture Sensor based on 555 Timer

555 timers determine their output signal based on two resistors and a capacitor.  I used the Astable 555 Square Wave Calculator to determine blink speeds for lighting an LED and for the 555 schematic.  To figure out what my capacitors were rated in Farads, i used the Electrostatic Capacitance Converter to convert uF to F.  My 2.2uF capacitor was 0.0000022F; that’s 2.2 times 10^-6.  I used a 100,000 ohm resistor for R1 and 10 ohm resistor for R2 to achieve a frequency of about 6.56 hz.  It looked like this:

Astable 555 Timer Circuit with Two Resistors

Astable 555 Timer Circuit with Two Resistors

To create a soil moisture meter, I used 2 parallel holes (1 inch apart) in a small piece of wood to put 2 bright common nails with wires attached (with solder) through the holes.  Speaker wire worked well here because it’s flexible, there are two wires within it, and it can easily be split apart.  I then replaced the 10 ohm R2 resistor with my soil moisture meter.

Astable 555 Timer Circuit with One Resistor and Soil Moisture Sensor

Astable 555 Timer Circuit with One Resistor and Soil Moisture Sensor

Here’s a short video of what it looks like in action:

The timing isn’t quite right, but it shows promise as a prototype that can be refined.

Mechanical and Kinetic Sculpture at Sprout

3 Feb

Tonight I visited Sprout in Somerville, MA for the Mechanical and Kinetic Sculpture meeting with Julian Gomes.   Also in attendance was Mike Beach who runs a Mechanics Steampunks Engineers Tinkers class, Joey Tochka, another Mike, and Jon Rosenfeld who helped tune and demo the lathe and mini mill at sprout.  Check out The Mechanical and Kinetic Sculpture wiki.

Trying to cut a steel bike frame on the lathe.  We lacked the proper cutting fluid to get it cutting smoothly.

Trying to cut a steel bike frame on the lathe. We lacked the proper cutting fluid to get it cutting smoothly.

Once tuned, we used the mill to create slots in aluminum.  Slotted aluminum happens to be perfect for creating a sliding tripod used in stereo photography.  I will likely be making a custom rig for my camera in the next few days to improve the quality of my anaglyph photos.  Here’s the mill in action after a tune-up:

I also recently ordered a laptop which already has me thinking about what design I will vinyl cut for the top.  This is what I’m thinking so far:

Blender screenshot showing bezier curve design

Blender screenshot showing bezier curve design

Using the Export Curve to Svg Path script for blender, I created the following design in inkscape which is almost ready to be cut on a vinyl cutter.

Vector design derived from blender file.  Made in inkscape.

Vector design derived from blender file. Made in inkscape.

Download the flower of life laptop skin svg file; I released the inkscape file into the public domain at  You can scale the svg and vinyl cut it to fit your laptop for free — this is for a wide-format laptop.

Stereographic Photos

2 Feb

Today I set out to create 3D anaglyph photos at night (anaglyph is an image that is viewed through red/blue glasses).  To create a 3D stereo image, you must take two shots: one from the left view and one from the right.  Ideally one has a 3D camera or two cameras rigged in parallel.  Since I only have one camera, I simply shifted my camera roughly 2.5 inches (eye width) between shots.  Low light meant taking long exposures and waiting for people to clear the scene since the shots were taken in sequence rather than at the same time.  StereoPhoto Maker is free software that magically aligns your shots to create convincing 3D.

Break out those red/cyan glasses.  Here are the results:

Somerville Theatre in 3D Anaglyph

Somerville Theatre in 3D Anaglyph

Davis Square statue in 3D anaglph

Davis Square Statue in 3D Anaglyph

Rules of thumb for taking stereo photos:

  • Set your camera on a flat surface that you can slide it on
  • Try to keep the foreground subject completely in the frame of the photo
  • Keep high enough off the ground, if you’re too close it can break the 3D effect
  • Keep the camera parallel, don’t angle it in or out;  Slide the camera directly left or right 2.5 inches (or eye width)
  • For close up shots or macro photos (shown below), you will move the camera much less of a distance

I had just fixed my TV-B-Gone:

TV-B-Gone Macro 3D Anaglyph

TV-B-Gone Macro 3D Anaglyph, the Separation Between Shots is Minimal

The completely free StereoPhoto Maker software I used can be downloaded here.  Below is the exact process I followed to generate the images shown here.

To process the left and right shots, simply go to File->Open Left/Right Images, then Adjust->Auto Alignment.  To view in anaglyph or side-by-side cross-eyed, choose your view from the Stereo menu.  The depth in the image at which the red and blue overlap is where objects change from going into the screen to popping out of the screen (look at the snow bank in the first shot).  When viewing the anaglyph image in Stereo Photo Maker, you can change how far into or out of the screen the image protrudes by using the Left and Right Arrow Keys (after auto-alignment).

Save your anaglyph through the File Menu, choose Save Stereo Image when viewing in Dubois (red/cyan) color anaglyph chosen in the Stereo menu.

In this video, learn how to make your own 3D glasses.

You might also want to check out StereoMovie Maker.  Note for linux users:  I always run Stereo Photo Maker using the default installation of wine (sudo apt-get install wine) on Ubuntu.

Lemon Juice Batteries and Joule Thieves

1 Feb

To kick off February Project Month, I wanted to explore lighting LEDs with small voltages generated by lemons.   By using the evilmadscientist joule thief circuit, one can power a 3 volt LED from sources as low as 0.3 Volts such as dying batteries.   I wondered whether a joule thief could power an LED with low voltages generated by lemon style batteries.  To begin, I created a cleanly packaged design for a copper/foil battery that could reliably read 1V on the voltage meter.

I created an instructable on how to create my 1 Volt Cell from 2 Pennies and Foil.  The design uses dish soap instead of lemon juice which I found intriguing and slower to evaporate.

1V cell measuring 1.2 Volts on a Multimeter
1V cell measuring 1.2 Volts on a Multimeter

I then created my joule thief by following these instructions on How to Make a Joule Thief.  The video shows the entire process of building.

Joule Thief Working with 1.5V Battery

Joule Thief Working with 1.5V Battery. Click for more pictures.

The joule thief worked like a charm for regular batteries generating about 1.5V.  It appears however, that my 1 volt battery design did not source enough current to generate the required 3 volts in the joule thief’s inductor.  This experiment is still far from conclusive however because there are more efficient joule thief designs that utilize capacitors.  I will also try testing a similar penny battery design aimed to generate 1.5 Volts.

Comments and insight are welcome.  Thanks!