I've been doing more late night research on electrodes. This is a good way to create an interface between machine and plant, or machine and animal, and it's basically a wire on a living surface, like a plant or your skin somewhere, and another one close by going out to complete a circuit. It passes current through this non metallic surface, between anode and cathode, and then you measure the resistance you detect. Then the medical ones get much more complicated, and easy to apply or stick to someone.
I started thinking about electrodes when planning a slug detector project, which would use the electrode in order to detect (or cast and then measure discrepancies in) an electrical field. Casting and detecting changes in, or just detecting electrical fields is a form of animal communication used in very primitive underwater animals, mostly to hunt prey or detect possible predators. Because slugs tend to go out on rainy nights, this would work mostly when there was water around this machine. It would generate or detect an electric field the size of a slug and then fire off an action if it does (like take a photo or open a beer trap), but now I'm moving on from molluscs and applying it to plants, as a kind of home made EEG.
The reason I'm talking about these things is I've been trying to make a garden sound object (GSO), or a Musical Raga Automaton (MRA) or an Arduino Powered Renewable Energy Symbiot (APRES), but really I've not really found a good acronynm for the thing so far. It's entered into the Newcastle Maker Faire 2010, as an outdoors exhibit.
It will also have a plant monitor to detect soil humidity, a light sensor and a thermistor to detect temperature.
So back to electrodes. Various ways to spread the pain/effect - http://www.bodyclock.co.uk/acatalog/tenselectrodes.html like with those electrodes, all more comfortable than a naked wire on your skin coming from some machine. It allows my musical automaton project to consider an even deeper symbiosis, whereby it could become the musical soundtrack for either a particular patch of land, or for a particular plant, a long lasting one, such as a bush or a tree.
This might be a more advanced one. This arduino page mentions simple electrodes.
Here is someone who has built a very simple windmill system. It could be good for a distributed windmill light or battery charging project. It's the simplest possible cardboard coil generator, which I'm sure could be attached to a rotor of some kind and made into a workshoppable item, using old hard disk magnets, LED lights and some old CD cases...
I thought more about green noise, and about going around and collecting some sounds from around bristol, maybe the water in the rivers and drains, the sound of the motorway at night, the air at the top of the hill... If I can get it sounding a bit like white noise, I'll know I'm close...
Today I got a step closer to a white noise circuit, but also built the Lady Ada Wave Shield, which I now hope to get working on my Seeeduino. Which brought me to consider once again the outdoor garden musical automaton(OGMA) and what sensors it should have, how it should interface with people and plants.
It should play each day differently through the year, so that in 30 degree heat you get more wave recordings and longer more intense sounds, using the higher amounts of energy collected by the solar panels and / or windmills on it. I don't know where to put a stop to it, but it will take a lot of testing - adding and removing piezos, wether sensing or buzzing, adding/removing light sensors, getting a temperature sensor and testing out a simple electrode or 10 on a plant (my poor aloe vera is wincing at the prospect).
In the winter, it will only play sparse sounds and try and calculate it's current remaining before attempting anything complex.
At night, the Noise Generating Automaton (NGA) will monitor certain readings, and go into a low power mode, still powered mostly by windmills charging some batteries. It will build a file with statistics based on these readings, and use that in the morning when it wakes up.
When light passes a certain threshold, it will generate a low frequency noise which increases as light does. When the sun is almost up, it will have got to being like a base tune, which jams following a pattern dictated by the temperature and humidity sensor's readings for the night.
Using Lady Ada's wave shield, some simple speaker housing, some piezo buzzers (here is an early test of one) and some natural resonant housing, I can produce enough amplification to create this hopefully inobtrusive garden soundtracker(HIGS). What is left to figure out is what to put it in that is both pleasing to look at and resistant to the humid newcastle climate... I'm considering Sugru and sealed glass or if all else fails, the typical plastic containers that you can buy at maplins again, for a few squid (Ah, another mollusc!).
The Garduino project will provide great help I think, as will Mike Skylar's experiments.
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