About 3 months ago, in caffeine fueled bravado, two of my friends and I decided to try to build an aquaponics farm in Botswana, a country in Southern Africa. After a lot of reading, field trips to a few impressive facilities, and a trip to Africa, where we secured a partnership with a local institution, we wisely decided to build a system locally first.
Aquaponics is a mixture of hydroponics (soil-less agriculture) and fish aquaculture (hence the cat’s laser-like focus). It is a symbiotic process, where the fish’s organic waste fertilizes the plants, and in return are supplied with filtered water. The only system input is fish food.
The two (2) black plastic boxes pictured above used to be one (1) 330 gallon IBC tote, which are usually used to store and transport fluid and other bulk materials. We cut the container about cut about two-thirds of the way up. The larger bottom tank holds 40 yellow perch for now – it can support about 80-90 fish. Water from the fish tank is pumped through the black pipe in 10 minute on/off cycles to the grow bed above. An Arduino housed in the blue box to the right controls the pump and also monitors water temperature. We plan on adding sensors to monitor the water chemistry (pH, nitrates, etc.) in the future.
The grow bed is media based. In other words, we use a mixture of rocks and expanded clay (the red stuff) to support the plant’s roots and act as a bio-filter to filter the water and convert fish waste (ammonia and nitrites) into plant food (nitrates). The filtered water falls back to fish tank through the PVC pipe (there are several small holes under the rock), which introduces oxygen via percolation and completes the mostly closed-looped cycle. A set of six (6) full spectrum T5 lamps provide the artificial light. The first crop of tomatoes, radishes, pepper, lettuce, and some wicked cucumbers is sprouting in the plastic containers and should be planted within the media within a day or two. We are expecting the first harvest in 4-6 months.
So now that we are seasoned farmers, we have launched a campaign to build a larger, floating-raft system in Botswana at a local institute of agriculture. We are currently in the fund raising phase on indiegogo. If everything falls into place, we will start construction in late summer (winter over there) of next year.
Pictured below is the reason we are pursuing this project. It hasn’t rained there since 2009. Combine that with the poor soil and the country has to import almost 100% of its vegetables and most fruits. We are hoping that water and energy efficient aquaponics based farming that produces hormone and chemical fertilizer free fish and plants is the answer.
Tracey, my wife, runs a lot. This year she is already over 2000 miles logged. She runs marathons and ultra-marathons and crazy things like 50 mile runs. We have long joked together that she clocks more miles running in a year than i put on my beloved 1999 Chevy Prism driving it to the train station and back. This made me think that i should make an odometer for her. I decided to do this for real a couple of weeks ago and had a prototype ready for her to open on Christmas morning.
Her immediate reaction? “You got me a box of wires and stuff?!” Once i explained it to her and showed it in action, she thought it was a lot of fun.
I initially wanted to use a real car odometer, but i didn’t have one handy. I went over to the fantastic American Science and Surplus and looked for some counters or an odometer there. While i didn’t find an odometer, they did have some 24v industrial counters from Durant. These are nice little counters that were (are?) made in Watertown, WI, not too far from our space. They are super simple devices. 6 geared dials have the numbers 0-9 on them. A solenoid ticks the rightmost number with each pulse of voltage it receives. When the dial on the right rolls over from 9 to 0, the next gear is ticked up by one and so on. These counters are not resettable or reversible, except by some manual intervention. I took the little guy apart and cranked the wheels over to where i wanted them.
A quick rummage through the hack rack turned up an 18V wall wart that we clipped the plug off of and used for our power source. Royce helped me out with this and with his help and a couple of alligator clips we proved that the 18V was enough to activate the solenoid and tick the counter up by 1. This particular counter moves 1 tick regardless of how long the voltage is applied. To crank up multiple ticks, i need to cycle the power on and off. I had an Adafruit MotorShield lying around that had all of the necessary high-voltage gear on it and we got the device up and running pretty quickly with it. I did not have time to build a circuit board just for this device, so the MotorShield is what is being used for the working device now. That wrapped up a quick night of experimentation at the space and at the end of it i had a working counter and the Arduino code to control it!
My next task was to integrate it with DailyMile, the social networking site that Tracey uses to log her runs and connect with her running friends locally and around the country. Thankfully, DailyMile has a nice little REST+JSON API that made it super easy to snag all of Tracey’s details. I used their ruby client, but will probably switch my app over to Python because i have been doing more Python development lately. The API returns a simple JSON structure for all logged activities and i simply snag that data and store it locally in a pretty-printed JSON file. A sample activity record and URL look like this:
"message":"My legs felt a little bit tired today but my lungs felt GOOD! I tried to stay relaxed and just enjoyed the feeling of breathing in and out. Really, a lovely Sunday morning.",
I save all of the activity events locally, but for this odometer, i am only interested in the “Running” events.
The ruby application runs forever and polls the DailyMile API every minute for new data and stops paging through the results if it finds entries that it has seen before. If any new runs are found, the app figures out how many miles are missing from the odometer and sends that value along as a byte to the arduino over the serial port using the serialport gem and waits for a successful response.
The device and code work right now, but the presentation leaves a lot to be desired, though, so i am working on a version with a more lovely display. I like the analog odometer feel and I think the next step will be to make some larger gears for this project on the CNC router at the space and build a bigger version. I’d also like to work with my father on a nice wooden case for the display and the gear.
The more immediate next steps will be to make a smaller circuit for this that doesn’t need a full arduino and a motor shield. I can control the solenoid with a transistor (like we did for the Beer Project). The bigger challenge will be to make the connectivity to the data from the API more compact. I would love for this device to be wireless, but i need to figure out how much i want it to cost. This would be a fun project to offer as a kit or for sale, but i don’t want it to cost close to 100 dollars, so i’ll be doing some more prototyping to make it a bit more standalone. The other challenge i have is that Tracey typically only uses her laptop, so there is no desktop machine sitting around that she would hook this up to so it will constantly update. I do have some new Xbee gear that might work, but i think the trickiest thing to design will be the standalone version that doesn’t need a computer connected to it.
Adam, Kevin and I have been working on a secure kegerator project. We made a kegerator that uses an Arduino Duemilanove with an RFID reader for access control, a solenoid for controlling the tap and a flow meter for recording how much beer was dispensed. We are reusing our Makerspace keycards and fobs for access. The system is pretty simple and only has a few components. We’ve done a couple of iterations on it so far and are currently working on a custom-etched Arduino shield for the components. While the system currently uses a little Nokia 5110 screen from AdaFruit, we are also working on a version that uses an android phone for display, data logging and cloud-connected goodness.
The old, tired way of storing and dispensing beer relies on cans and refrigerators. This simply won’t do for today’s tech-savvy connoisseur.
Our kegerator has an RFID reader that hangs off the front. This shot is from an earlier version that did not have a screen attached. Classy.
The screen has a glorious 1-bit Milwaukee Makerspace logo (courtesy of the generous folks at RasterWeb, Inc.) and an inviting message. After the beer is poured, the amount of beer dispensed will also be displayed.
The kegerator is very perceptive. It uses advanced computer vision to detect that you are thirsty and suggests that you would like a beer.
Kevin uses his Makerspace keyfob to badge in and is greeted by his stage name.
With his identity verified and his tankard filled with a tasty brew, Kevin can do nothing but obey.
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