66% or better

7-Foot DIY Wind Turbine Proves Size Matters


When [brokengun] decided to build a 7 ft diameter wind turbine, he had no idea how to even start, so he did as most of us would do and read some books on the topic. His design criteria was that it would be simple to construct and use as many recycled parts as possible. This wind turbine charges a 12 volt battery which can then be used to power a variety of gadgets.

Although made from recycled components, this isn’t a thrown together wind turbine. A lot of thought went into the design and build. [brokengun] discusses matching the blade size to that of the generator in order to maximize power and efficiency.  The design also incorporates a feature that will turn the turbine perpendicular to the wind if the wind-speed gets to high. Doing this prevents the turbine from being damaged by strong gusts.

For the main support/hub assembly, a Volvo 340 strut was used because they are widely available, cheap and known for being long-lasting. The tail boom is made from electrical conduit and it’s length is determined by the size of the main fan rotor. The tail vane is made from steel sheet metal and its surface area is also dependent on the fan rotor size to ensure that the turbine functions properly. The blades are made from wood but instead of making them himself, [brokengun] felt these were worth ponying up some cash. [brokengun] also scored a 30 ft high lattice tower an airport was getting rid of. This worked out great as it’s just the right height for a turbine of this size.

[Read more...]

Software-Controlled Per-Port Power Switching for USB Hubs

[Befi] wanted to add a second stage backup disk to his ODROID embedded-board server, which typically draws ~1.5W at idle. After adding the disk, he saw power consumption increase by 2W when the new disk wasn’t spinning. He thought about using one of those USB hubs with the adorable little rocker switches for each port and replacing them with transistors, but that was going to be messy. After some poking around in the USB standard, he found that most support per-port power switching (PPPS), and set about to hack a USB hub to enable software-controlled per-port switching.

[Befi]‘s NEC hub uses a uPD720112 chip which supports PPPS according to the datasheet. After tying the configuration pin labeled GANG_B to +3.3V, the hub declared itself PPPS-compatible. Of course, the manufacturer saved a penny or two by omitting the  individual switches, so [Befi] added an open-drain NMOS to each port. He is using this program to switch the port on and off and made the switching transparent with autofs. [Befi]‘s current script has the bus ID and device ID of the hub hard-coded, but he intends to update it to find them automatically. This hack saves him 10W on average, which is about €30 ($40) per year.

If your hub is under powered, you could try adding an external power supply.

$1 Coin Cell Charger


Sure, coin cells usually last a long time — but do you really want to buy new ones and throw the old ones out? The LiR2032 coin cell is a rechargeable lithium battery, for which you can build a charger at around $1.

The 5 minute hack starts with a TP4056 lithium charging circuit, which is a great DIY board designed to charge high-capacity cells at about 1A. Luckily, it is pretty easy to modify the board to charge lower capacity batteries. It’s just a matter of replacing resistor R4, and a little bit of soldering! [Read more...]

A New Way to Heat People

heat spotlight

[Leigh Christie] is a researcher at MIT, and he’s developed an interesting solution to heating people, not buildings.

His TEDx talk, “Heating Buildings is Stupid,” demonstrates the MIT SENSEable City Laboratory’s efforts to tackle energy issues. Their research focuses on finding an alternative to the staggering waste of energy used to heat large spaces. Although TED talk articles are a rarity at Hackaday, we think this idea is both simple and useful. Also, [Leigh] is the same guy who brought us the Mondo Spider a few years ago for the Burning Man exhibition. He’s a hacker.

Anyway, what is it? The system he’s devised is so simple that it’s brilliant: a person-tracking infrared heat spotlight. Using a Microsoft Kinect, the lamp follows you around and keeps the individual warm rather than the entire space. [Leigh] has grand plans for implementing what he calls “Local Heating” in large buildings to save on energy consumption, but smaller-scale implementations could prove equally beneficial for a big garage or a workshop. How much does your workspace cost to heat during the winter? Hackerspaces seem like the perfect test environment for a cobbled-together “Local Heating” system. If anyone builds one, we want to hear about it.

Check out the full TEDx talk after the break.

[Read more...]

Peltier Joule Thief Power Supply

Peltier Joule Thief Power Supply

[Steven] manages to power an LED for 15 minutes using hot and cold water as a battery. He does this using the thermoelectric effect also known as the Seebeck effect, Peltier effect or Thomson effect. This isn’t particularly new; in fact there are commercial products that you can use to charge a cell phone using a small campfire or internal burner that works on the same principle.

What is interesting about [Steven’s] device is that he uses a salvaged Peltier device not meant for generating electricity, coupled with a home built joule thief circuit. In the video he describes how the joule thief functions and powers the LED using the small voltage generated by the Peltier device. The energy for the thermoelectric effect is conducted from a hot water bath through aluminum plates, through the positive and negative sides of the Peltier device, through more aluminum plates and finally into a cold water bath. As the heat energy transfers through the Peltier device a small electric current is generated and flows in two small wires coming out the side of the device.  The energy generated by the Peltier device is stored in the joule thief and periodically dumped at a voltage high enough to forward bias the LED “on” for a brief moment. Technically the LED is flashing but at a frequency too high for our eyes to see. As the hot water bath cools, the LED goes from very bright, to dim, to off in about 15 minutes.

Not a very practical power supply but still quite the parlor trick. He wraps up the tutorial specifying that a TEG thermoelectric generator would be a much better choice for generating power and can handle much higher temperatures. You can watch the video after the break.

[Read more...]

[Charles's] Epic “Total-Recap” GoKart Post


If you’ve built an electric vehicle in the past few years, you probably owe [Charles] a couple of beers. Now you can feel more indebted to him after you read his 17,500-word, 10-part post covering everything you need to know about electric go-kart design. You’ll want to grab a sandwich to keep you company.

You probably recall the Chibikart from posts earlier this summer, which is one of an endless list of EV projects [Charles] has up his sleeve. He’s been teaching MIT students how to build EV karts for a while now, and this total-recap “2.00gokart” novel is [Charles's] way of sharing the wealth. This is more than a simple how-to guide, though. Instead, it reads like a teacher’s edition of GoKarting 101, with a few brief and important histories, walk-throughs of how the class evolved, exhaustive links to vendors, graphs, videos, and plenty of reference and documentation.

If you have even the slightest interest in electric vehicles, do yourself a favor and give it a browse. There are a couple of videos after the break, and if you need some more motivation, check out the EV skateboard that uses a lot of the same parts.

[Read more...]

Solar Camping on Steroids

solar battery (Large)

[Rick] does a lot of camping, but he loves his electronics. So he’s now on his third iteration of his solar-powered battery box, and it packs quite the punch!

It’s a pretty simple build, but very effective. [Rick] is using a 200W solar panel, a 20 Amp MPPT solar charge controller, a large 100Ah Military Spec Deka 6TMF deep cycle battery, three 12 volt car accessory outlets, and to box it all up — an inexpensive plastic tote from Walmart to keep it dry in bad weather. The only problem we can see with this is that since the battery isn’t a sealed gel cell, it could out gas inside the tote which might cause him problems down the road. He’s aware of this though so the lid is only on when it needs to be.

This unit can power pretty much anything that runs on 12 volts, from USB devices, to camping light batteries, air pumps for air mattresses, C-PAP machines via the included A/C inverter, and it can even run an EdgeStar FP-430 portable fridge/freezer for 3+ days before even needing to plug in the solar panel for recharging! Total system cost is a bit high at around $1000 — but that includes the portable fridge, solar panels, and all accessories and miscellaneous hardware that went into assembling the system.

Stick around after the break to see the video demonstration.

[Read more...]