Self-regulating water heater

netduino_controlled_energy_saving_water_heater

Most everyone is looking to live a little greener these days, with motivating factors typically being the preservation of the environment or financial considerations. [Fabien] fit into the latter category after realizing that about 25% of his monthly gas bill went to heating the water he and his family use each day. After a few calculations, he found that they only required hot water 68 of the 168 hours per week that the water heater was typically running. He figured the best way to save a few dollars was to rig the water heater to turn itself down when it wasn’t being used.

He connected a servo to the temperature control knob on his water heater, allowing it to be adjusted by a microcontroller. Having a rough idea as to the schedule his family keeps during an average week, he wrote an application for his Netduino that would actuate the servo when needed. A DS1307 real-time clock was wired to the Netduino for accurate timekeeping, so as to ensure [Fabien’s] wife never had to endure a cold shower.

It’s a shame that most water heaters don’t ship with some sort of programmable thermostat like you see with newer HVAC systems, but this hack is definitely a step in the right direction.

Continue reading to see his power-saving water heater in action.

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BAMF2010: SolarPump Charging Station

Amidst the noise of a bazillion robots and Tesla coils at the 2010 Bay Area Maker Faire, we located a bubble of usable WiFi, and got a nearby power charge to boot. If nothing else here, we want this:

The SolarPump Charging Station is a self-contained oasis of free power for laptops, cel phones and even electric bikes. This charging station is one of several designs created by Sol Design Labs of sunny Austin, Texas. No bigger than a bus stop (and way cooler looking), it’s like the ultimate case mod, repurposing a vintage Citgo gas pump and recycled metals for more modern needs. Three large Sanyo solar panels provide power for devices and shade for users, while topping off the internal 24V 100AH battery for nighttime use (with LED lighting) or cloudy days. The end result transcends “green” — the SolarPump is simply appealing at a visceral level, managing to be simultaneously fun, attractive and practical. Did we mention wanting one? We totally want one.

Making a rail gun (again!)

[Rp181] is at it again with version 2 of his rail gun project. The original did have some power with 18 400V 3900uf capacitors, but he’s ramped it up to now using 40! Reaching more than double the amount of joules of energy, 12kJ vs. the 5.6kJ! Some other changes include a new injector solenoid setup and revision 3 of his breakwire chronograph. Sadly, he doesn’t mention if this is as green as his first rail gun. Check out a video of just the injector firing and an animation explaining some new updates after the jump.

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Laser spiro made from junk

P6080017

Sometimes we need someone like [FireMyLaser] to show us that you really don’t need things like custom PCB’s, expensive tools, or laser cutters to pull of a hack. His laser spiro subsists mostly of  toothpicks, hotglue, and determination. It is a two motor spiro with a base motor and a motor mounted in a  spinning cage. The cage gets power through brushes much like other projects we’ve covered. See a video of it in action after the break.
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Tapping Tree Power

[bugloaf] tipped us off about this flower power hack. University of Washington researchers, [Babak], [Brian], and [Carlton] have developed very low power circuits to run directly off of trees. This builds upon the work of MIT researchers and Voltree Power. A voltage of up to around 200mV is generated between an electrode in a tree and an electrode in the ground. Identical metals can be used as electrodes as the process is not like that of a lemon or potato battery. The significant development here is the use of a boost converter and exceptionally low power circuits. What kind of applications can you come up with for this source of power? Maybe you could try to combine this power with the power from donuts and hair.

Energy efficient fridge hack

Green_Freezer

We’ve already covered a pipe bomb mini-fridge this week, but inventor [Tom Chalko] provides us with today’s fridge hack. He noticed that chest-style (laying down, see above) freezers were more energy efficient when compared to normal stand up refrigerators at the same size, despite the colder temperatures involved. This is largely due to the fact that these chest-style freezers keep cold air in like water in a bowl, even if the lid is open. He has written a very thorough report on his findings (pdf), as well as a detailed walk through of the manageable task of converting a chest-style freezer into a chest-style fridge. In the end, his fridge only used 103 Wh of electricity on the first day to reach and maintain between 4° and 7° C (39° to 45° F), and he noted that 30% of that was just getting it up to temperature. After that, the fridge only turned on for roughly 90 seconds an hour, making it a very quiet fridge as well.