Generating Electricity With Swing Sets

May 11, 2012 by Caleb Kraft 7 Comments

[Guelherme Pena Costa] came up with an idea to light up a swing set using the motion of the people swinging on it to generate electricity. The goal was to get people to enjoy the playground at night and we think, this might actually be a pretty good way to achieve that. People love blink lights, especially if they are interactive.

To Light the LEd ropes, [Guelherme] has attached a gear motor to the frame of the swing set and an arm to the chain. When the swinger swings, it spins the motor generating between 6 and 10 volts at 230-400 mA. As you can see in the video below, that works fine to illuminate the LEDs, though we think a charging circuit to allow the lights to stay lit for longer would also be cool.

Sun-powered Stirling Engine With Automatic Tracking

May 2, 2012 by Mike Szczys 32 Comments

Check out this solar-powered Stirling engine (translated). The build is part of a high school class and they packed in some really nice features. The first is the parabolic mirror which focuses the sun’s rays on the chamber of the engine. The heat is what makes it go, and the video after the breaks shows it doing just that.

But the concept behind the mirror makes for an interesting challenge. The light energy is focused at a narrow point. When the sun moves in the sky that point will no longer be at an efficient position to power the engine. This issue is solved by a pair of stepper motors which can reposition the dish. It’s done automatically by an Arduino Uno which makes readings from four LDR (photoresistors) in that cardboard tube mounted at the top of the dish. If the light intensity is the same for all four, then the tube is pointed at the sun. If not, the motors are tweaked to get the best angle possible.

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Monitoring A Solar Array Output

April 23, 2012 by Mike Szczys 7 Comments

After years of hoping and wishing [Dave] finally took the plunge and installed solar panels on the roof of his house. He’s got twelve panels that are each rated at 240 Watts! But just having them sitting there and pumping power back to the grid isn’t enough. Understandably, he decided to add his own solar array monitor so that he could see just what those babies are bringing to the party.

The solar array has an inverter which takes the DC from the cells and converts it to mains voltage AC for use on the grid. The system includes a panel meter which you’d normally find on the supply to the house. All he needed to do is find a way to grab the data from that device. It’s an Elster meter, and offers two types of feedback: a blinking LED that corresponds to each Watt-hour passing through the meter, and an IrDA port which provides a more error-proof method of reading data. Monitoring the 1 Wh pulse is quite a popular method for keeping track of your electric meter, but if your hardware misses a pulse the data will be off. [Dave] chose to use a light sensor to monitor the IrDA output, which is encoded data. As long as you can read the protocol, which has been published by Elster, a transmission can be missed now and again without disturbing the overall power consumption data.

Harvesting And Graphing Wireless Household Utility Meter Info

April 9, 2012 by Mike Szczys 46 Comments

Both our electrical meter and our gas meter are located in the basement of our house (we recently had the gas meter moved outside though). When people see this they always ask if the meter readers have to come inside once a month. The answer is no, these meters broadcast usage data which is picked up once a month when a utility company vehicle drives down the street. If you have wireless meters in your house, here’s a way to harvest and graph the wireless data so that you can analyze your usage patterns.

The hardware used here is a special USB dongle. This has a 900 MHz radio which picks out the packets from a reasonably large list of meter types, and pushes them through the USB interface. In the image above you can see that an Arduino with a USB host shield is used, but there are also drivers if you want to connect this directly to your computer.

We looked around and didn’t find any specifics on the hardware used on that board. But it can’t be all that hard to make one of these at home… the populated board seems to have just two ICs and a few passive components. Anyone up to the challenge of hacking together their own packet sniffer? We wonder if the Next HOPE badge could pull down the data?

[Thanks Chris]

New Dirigibles Are Power Plants In The Sky

March 30, 2012 by Mike Szczys 87 Comments

We wonder if a floating wind turbine generator (translated) like this one would alleviate some of the complaints we hear about ground-based turbines. This huge helium-filled structure is designed to generate electricity at high altitude, where winds are stronger and blow much more consistently than near ground level. We’ve read complaints at the unsightliness of wind farms, and the noise that they make as the turbines spin. A test run took place at only 350 feet, but this generator is meant to fly at an altitude of 2000 feet. We’d bet it’s much less obtrusive and much quieter at that distance.

There isn’t a whole lot to the lighter-than-air assembly. It’s got an aerodynamic balloon with stabilizing fins, and a propeller attached to a generator at the center. The tether that holds it in place also carries the conductors which translate the power down to the ground. There is mention of a fail-safe system that allows for a slow descent if it get gets away from its tether, so you shouldn’t have to worry about the sky falling on you.

It’s certainly an interesting idea. For some reason this makes us think of the space-based solar generator panels found on Larry Niven’s Ringworld.

[via Reddit]

Coin Cell Battery Charger

March 28, 2012 by Mike Szczys 19 Comments

[Jay Kickliter] built his own coin cell battery recharger. This won’t work on the vast majority of coin cells as they are manufactured as disposable parts. But there are rechargeable options out there with model numbers that start with LR instead of CR. In this case he tailored the charging circuit around MCP73832 IC and chose components best suited for charging his 110 mAh LR2450. But we believe all of the LR options out there are rated for 3.6V so altering his design for use with different models should be a breeze.

We’ve been unhappy with the use of disposable coin cell batteries for some time. Sure, in a real-time clock where the cell might last 6-8 years this is not very wasteful. But in an Apple TV remote that gets a lot of use, we hate the choice of a disposable battery. All of our less-hip remotes which use AA or AAA have NiMH rechargeables in them and have used the same pair for year and years. So we’re happy to see this charger project come along.

Now the bad news. We looked around and indeed you can find LR2032; a rechargeable replacement for the CR2032. But the capacity rating falls way flat. The model we looked at boasts only 50 mAh while the disposable CR2032 offers something along the lines of 240 mAh. Hopefully this will change as battery tech evolves.

Hot Dirt Keeps Your Plants Happy In The Winter Months

March 19, 2012 by Mike Szczys 9 Comments

[Craig] tried heating his greenhouse last winter, but really only managed to push the limits of his utility bills. This time around he took a different approach by building a system to warm the soil in which his vegetation is planted.

The core of the system is this box which houses the plants. It is lined with heating tape along the bottom which warms a layer of dirt. The plants are in pots, but since those are surrounded by the dirt it doesn’t really inhibit the warming properties of the soil. The controller takes into account the temperature inside the box, as well as ambient temperature in the greenhouse. When it’s a bit too cold the controller will close the lid, which is covered with translucent plastic. This makes sure the temperature around the plants won’t fall below about 41.5 degrees Fahrenheit.

This really takes the work out of caring for you plants in the winter. What would have been a multiple-times-per-day visit can be limited to every day or two. Now he just needs to expand this to regulate temperature and humidity in the greenhouse itself, kind of like this other hack.