Full Size 3D-Printed Wind Turbine

June 2, 2021 by Bryan Cockfield 29 Comments

Wind energy isn’t quite as common of an alternative energy source as solar, at least for small installations. It’s usually much easier just to throw a few panels and a battery together than it is to have a working turbine with many moving parts that need to be maintained when only a small amount of power is needed. However, if you find yourself where the wind blows but the sun don’t shine, there are a few new tools available to help create the most efficient wind turbine possible, provided you have a 3D printer.

[Jan] created this turbine with the help of QBlade, a piece of software that helps design turbine blades. It doesn’t have any support for 3D printing though, such as separating the blades into segments, infill, and attachment points, so [Jan] built YBlade to help take care of all of this and made the software available on the project’s GitHub page. The blades are only part of this story, though. [Jan] goes on to build a complete full-scale wind turbine that can generate nearly a kilowatt of power at peak production, although it does not currently have a generator attached and all of the energy gets converted to heat.

While we hope that future versions include a generator and perhaps even pitched blades to control rotor speed, [Jan] plans to focus his efforts into improving the blade design via the 3D printer. He is using an SLA printer for these builds, but presumably any type of printer would be up to the task of building a turbine like this. If you need inspiration for building a generator, take a look at this build which attempted to adapt a ceiling fan motor into a wind turbine generator.

The Dynamotor Simplified

April 11, 2021 by Al Williams 28 Comments

[Robert Murray-Smith] doesn’t like the price of inverters to convert DC to AC. That led him to build a dynamotor, or what is sometimes called a motor-generator set. These devices are just DC motors driving a generator. Of course, motors can also be used as generators and [Robert] had a stack of brushless motors in the form of PC fans. A two-fan dynamotor was born.

The brushless motors are attractive because, traditionally, the brushes are what usually fail on a dynamotor. The fan that will act as a generator needs some surgery, but it is simple. He scraped off all the control electronics and connected wires to the coils to form a three-phase generator. There’s no need for the fan blades in that configuration, either. If you were using ordinary motors and a generator, getting shafts concentric would be an important task. With the fans, it is simple to just line up the mounting holes and you get perfect alignment for free.

How does it work? [Robert] has a second video showing the output on a scope. You can see both videos below. The dynamotor makes a good-looking sine wave, probably much better than most reasonable-priced solid state inverters. He didn’t mention how much current he could successfully draw, but it probably isn’t much. You’d also need a transformer to replace a commercial inverter that would put out line voltage, so that would be some more loos in the system. On the other hand, if you wanted AC at a lower voltage, you might just replace all the transformers, if you were building a piece of gear yourself.

We’ve looked at how these things work in some detail. There were common in old tube radios, particularly military ones.

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Generator Runs On Natural Gas With Field Expedient Tip

March 3, 2021 by Tom Nardi 111 Comments

Many small gasoline engines can be safely modified to run on natural gas or propane with a kit that replaces the carburetor and adds a regulator, providing a reliable alternative fuel source in the event that gasoline is difficult to obtain in an emergency situation. This seat of the pants hack by [HowToLou] is definitively not the safe way to run your generator on natural gas, but if you ever find yourself in a situation where getting the power back on might be a literal matter of life or death, it’s a tip worth keeping in mind.

The basic idea here is that you feed natural gas (though propane should also work) directly into the engine’s intake by way of a hose attached to the air filter box. While cranking the engine, a valve on the gas line is used to manually adjust the air–fuel mixture until it fires up. It’s an extremely simple hack that, in a pinch, you can pull off with the parts on hand. But as you might expect, that simplicity comes at a cost.

There are a few big problems with this approach, but certainly the major one is that there’s nothing to cut off the flow of gas when the engine stops running. So if the generator stalls or you just forget to close the valve after you shut it down, there’s the potential for a very dangerous situation. Additionally, the manual gas valve will be at odds with a generator that automatically throttles up and down based on load. Though to be fair, there are certainly generators out there that simply run the engine flat-out the whole time.

Much like his DIY generator interlock plate that we covered last month, we imagine this project may rub some folks in the wrong way. Admittedly, this isn’t a modification that you should take lightly and certainly not something you’d want to rely on for long-term use. But as the recent situation in Texas has reminded us, drastic times can occasionally call for drastic measures.

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How To Design A Custom Generator Interlock Plate

February 22, 2021 by Tom Nardi 85 Comments

If you connect a generator to your home’s main electrical panel when the power goes out, you need to make sure the main breaker is shut off. Otherwise, when the power comes back on, you (or the linemen) are going to have a bad time. There are commercial interlock plates which physically prevent the generator and main breakers from being switched on at the same time, but since they tend to be expensive, [HowToLou] decided to make one himself.

The hardest part of this project is designing the template. It needs to be carefully shaped so its resting position prevents the generator’s breaker from being switched on under normal circumstances, but once the main is turned off and out of the way, you should be able to lift it up and have the clearance to flip the lower breaker. Spending some quality time at the breaker box with tape and a few pieces of cardboard is going to be the easiest way of finding the proper shape.

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Human-Powered Laser Gun Makes Battery-Free Target Practice

April 26, 2020 by Donald Papp 15 Comments

[Dirk] shared a fascinating project of his that consists of several different parts coming together in a satisfying whole. It’s all about wanting to do target practice, indoors, using a simple red laser dot instead of any sort of projectile. While it’s possible to practice by flashing a red laser pointer and watching where it lands on a paper target, it’s much more rewarding (and objective) to record the hits in some way. This is what led [Dirk] to create human-powered, battery-free laser guns with software to track and display hits. In the image above, red laser hits on the target are detected and displayed on the screen by the shooter.

Right under the thumb is the pivot point for the lever, and that’s also where a geared stepper motor (used as a generator) is housed. Operating the action cranks the motor.

There are several parts to this project and, sadly, the details are a bit incomplete and somewhat scattered around, so we’ll go through the elements one at a time. The first is the guns themselves, and the star of the show is his 3D printed cowboy rifle design. The rifle paints the target with a momentary red laser dot when the trigger is pressed, but that’s not all. [Dirk] appears to have embedded a stepper motor into the lever action, so that working the lever cranks the motor as a generator and stores the small amount of power in a capacitor. Upon pulling the trigger, the capacitor is dumped into the laser (and into a piezo buzzer for a bit of an audio cue, apparently) with just enough juice to create a momentary flash. We wish [Dirk] had provided more details about this part of his build. There are a few more images here, but if you’d like to replicate [Dirk]’s work it looks like you’ll be on your own to some extent.

As for the target end of things, blipping a red dot onto a paper target and using one’s own eyeballs can do the job in a bare minimum sort of way, but [Dirk] went one further. He used Python and OpenCV with a camera to watch for the red dot, capture it, then push an image of the target (with a mark where the impact was detected) to a Chromecast-enabled screen near the shooter. This offers much better feedback and allows for easier scoring. The GitHub repository for the shot detector and target caster is here, and while it could be used on its own to detect any old laser pointer, it really sings when combined with the 3D printed cowboy rifle that doesn’t need batteries.

Not using projectiles in target practice does have some benefits: it’s silent, it’s easy to do safely, there is no need for a backstop, there are no consumables or cleaning, and there is no need to change or patch targets once they get too many holes. Watch it all in action in the video embedded below.

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Open Source $50 Water Turbine From Repurposed Parts

December 20, 2019 by Danie Conradie 37 Comments

Easy access to reliable electrical power is something a lot of us take for granted, but in developing countries or after natural disaster, it can be a rare commodity. [Daniel Connelly] has been working hard to develop infrastructure people can build themselves, and his latest project is a 200 W water turbine (video after the break) that can be built for about $50.

The core of the system is a wheel and motor from a hoverboard. What looks like 110 mm PVC tubing is connected together in a U-shape that can be mounted over the wall of a man-made channel. The inlet side is shorter than the outlet, and the system must be filled with water to allow the flow to start, like a siphon. The first two versions had the impeller sitting on the end of the outlet tube. V1 used a scrap plastic radial impeller of unknown origin, and did not work at all. V2 had a 3D printed impeller that worked pretty well, but the rotation speed wasn’t high enough to produce the voltage that [Daniel] wanted.

V3 used a large computer fan that was mounted in the short horizontal piece of section of tubing at the top of the system. It worked spectacularly well, producing about 55 V AC over a single phase of the motor, which should hopefully end up producing about 90 V DC and 200-500 W after rectifying the 3-phase motor output. This only however indicative, we would really like to see it tested with different loads connected. The output will also be dependent on the flow rate and head pressure of a particular stream/channel/river, and [Daniel] admits that they had pretty much ideal conditions for their tests. If hoverboard motors are hard to come by, a motorcycle alternator should also work well.

[Daniel] is still working out the kinks of the system, but as with his other designs on OpenSourceLowTech he will release the full open source design and tutorials as soon as he is ready. We are looking forward to seeing the system implemented out in the wild. For off-grid power, home built and 3D printed wind generators are another popular topic around here, if you don’t have a handy channel nearby.

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Spin Me Right Round, Baby: Generator Building Experiments For Mere Mortals

August 13, 2019 by Brian McEvoy 38 Comments

How many of you plan to build a wind-powered generator in the next year? Okay, both of you can put your hands down. Even if you don’t want to wind your coils manually, learning about the principles in an electric generator might spark your interest. There is a lot of math to engineering a commercial model, but if we approach a simple version by looking at the components one at a time, it’s much easier to understand.

For this adventure, [K&J Magnetics] start by dissect a commercial generator. They picked a simple version that might serve a campsite well, so there is no transmission or blade angle apparatus to complicate things. It’s the parts you’d expect, a rotor and a stator, one with permanent magnets and the other with coils of wire.

The fun of this project is copying the components found in the commercial hardware and varying the windings and coil count to see how it affects performance. If you have ever wound magnet wire around a nail to make an electromagnet, you know it is tedious work so check out their 3D printed coil holder with an embedded magnet to trigger a winding count and a socket to fit on a sewing machine bobbin winder. If you are going to make a bunch of coils, this is going to save headaches and wrist tendons.

They use an iterative process to demonstrate the effect of multiple coils on a generator. The first test run uses just three coils but doesn’t generate much power at all, even when spun by an electric drill. Six windings do better, but a dozen finally does the trick, even when turning the generator by hand. We don’t know about their use of cheap silicone diodes though, that seems like unintentional hobbling, but we digress.

Making turbine blades doesn’t have to be a sore chore either, and PVC may be the ticket there, you may also consider the vertical axis wind turbine which is safer at patio level. Now, you folks building generators, remember to tip us off!

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