PTPM Energy Scavenger Aims for Maintenance-Free Sensor Nodes

[Mile]’s PTPM Energy Scavenger takes the scavenging idea seriously and is designed to gather not only solar power but also energy from temperature differentials, vibrations, and magnetic induction. The idea is to make wireless sensor nodes that can be self-powered and require minimal maintenance. There’s more to the idea than simply doing away with batteries; if the devices are rugged and don’t need maintenance, they can be installed in locations that would otherwise be impractical or awkward. [Mile] says that goal is to reduce the most costly part of any supply chain: human labor.

The prototype is working well with solar energy and supercapacitors for energy storage, but [Mile] sees potential in harvesting other sources, such as piezoelectric energy by mounting the units to active machinery. With a selectable output voltage, optional battery for longer-term storage, and a reference design complete with enclosure, the PPTM Energy Scavenger aims to provide a robust power solution for wireless sensor platforms.

Flat Pack Generators

We just wrapped up the Power Harvesting challenge in the Hackaday Prize, and with that comes some solutions to getting power in some very remote places. [Vijay]’s project is one of the best, because his project is getting power in Antarctica. This is a difficult environment: you don’t have the sun for a significant part of the year, it’s cold, and you need to actually get your equipment down to the continent. [Vijay]’s solution was to use one of Antarctica’s greatest resources — wind — in an ingenious flat pack wind turbine.

There are a few problems to harvesting wind power in a barren environment. The first idea was to take a standard, off-the-shelf motor and attach some blades, but [Vijay] found there was too much detent torque, and the motor would be too big anyway.

The solution to this problem was to wind his own motor that didn’t have the problems of off-the-shelf brushless motors. The design that [Vijay] settled on is a dual axial flux generator, or a motor with a fixed stator with magnets and two rotors loaded up with copper windings. Think of it as a flattened, inverted version of the motor on your drone.

One interesting aspect of this design is that it takes up significantly less space than a traditional motor, while still being able to output about 100 Watts with the wind blowing. Add in some gearing to get the speed of the rotor right, and you have a simple wind generator that can be set up in minutes and carried anywhere. It’s a great project, and we’re glad to see this make it into the finals of The Hackaday Prize.

Out Of Batteries For Your Torch? Just Use A Mini Nitro Engine

We can certainly relate to an incomplete project sowing the seed for a better one, and that’s just what happened in [JohnnyQ90]’s latest video. He initially set out to create an air compressor powered by a nitro engine, and partially succeeded – air was compressed, but not nearly enough to be useful.

Instead, he changed tack and decided to use the 1 cc engine to make a small electric generator. [JohnnyQ90] is, of course, no stranger to the nitro engine, having previously brought us the micro chainsaw conversion, and nitro powered rotary tool. This time round, the build is a conceptually simple task: connect an engine to a DC motor and you’re done. But physically implementing it in an elegant way is a different story, and this is always where [JohnnyQ90] shines; we never get tired of watching him produce precision parts on the lathe. A fuel tank is made from a modified Zippo can and, courtesy of a CNC milled fan and 3D printed shroud, the motor air cools itself.

Towards the end of the video, [JohnnyQ90] plays with the throttle a little, causing the bulb connected to the generator to brighten accordingly. It might be fun to control the throttle with a servo and try to regulate the voltage on the output under different load conditions.

We love novel ways of creating electricity; previously we’ve written about how to generate power from a coke can, as well as this 120 W thermoelectric generator (TEG) setup.

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Lightning Generator from Electric Lighter

Generating high voltages isn’t too hard. A decent transformer will easily get you into the 100s of kilovolts, provided you’re a power company and have access to millions of dollars and a substation to put it. If you want to go above that then things start getting difficult, and most tend to look in other places for high voltages such as voltage multipliers.

These devices use nothing but capacitors and diodes, as [Jay] from [Plasma Channel] shows us how to build a small desktop version of a voltage multiplier that can produce almost 70 kV. That’s enough to throw a substantial spark, powered by nothing but a rechargable battery found in an electric lighter. They can also be cheaper than transformers to a point, since they require less insulation and less copper and iron. The voltage multiplier works in stages, with each stage boosting the voltage to a critical level above the stage before it similar to a Marx generator.

Similar designs are used by laboratories to simulate lightning strikes, and can generate millions of volts. They’re a cost-effective way of generating huge voltage pulses and studying everything from the effects of lightning on various equipment to generating X-rays in fusion power tests. We’ve even seen them in use in lasers.

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Supercapacitors In A Servo: The “Forever” Flashlight

The principle is well understood: use a motor in reverse and you get a generator. Using this bit of knowledge back in 2001 is what kick-started [Ted Yapo]’s Hackaday Prize entry. At the time, [Ted] was searching for a small flashlight for astronomy, but didn’t like dealing with dead batteries. He quickly cobbled together a makeshift solution out of some supercapacitors and a servo-as-a-generator, hacked for continuous rotation.

A testament to the supercapacitors, 17 years later it’s still going strong – leading [Ted] to document the project and also improve it. The original circuit was as simple as a servo, protection diode, some supercapacitors, and a LED with accompanying resistor; but now greater things are afoot.

A DC-DC boost converter enables constant power through the LED, regardless of the capacitor voltage. This is achieved by connecting the feedback pin of an MCP1624 switcher to an INA199 current-shunt monitor. The MCP1624 kicks in at 0.65V and stays active down to 0.35V. This is all possible due to the supercapacitors, which happily keep increasing current as voltage drops – all the way to 0.35V. Batteries are less ideal in this situation, as their internal resistance increases as voltage drops, as well as increasing with age.

When testing the new design, [Ted] found that the gears on his servos kept stripping when he was using them to charge capacitors. Though at first he attributed it to the fact that the gears were plastic, he realized that his original prototype from 2001 had been plastic as well. Eventually, he discovered the cause: modern supercapacitors are too good! The ones he’d been using in 2001 were significantly less advanced and had a much higher ESR, limiting the charging current. The only solution is to use metal gear servos

Want to read more about boost converter design? We have the pros and cons of microcontrollers for boost converters, or this neat Nixie driver for USB power.

Delightful Electromechanical Build Of A Jet Engine Model

[InterlinkKnight]’s jet engine model is a delight to behold and to puzzle out. Many of us have been there before. We know how to build something, we know it’s not the most up-to-date approach, but we just can’t help ourselves and so we go for it anyway. The result is often a fun and ingenious mix of the mechanical and the electrical. His electric jet engine model is just that.

Being a model, this one isn’t required to produce any useful thrust. But he’s made plenty of effort to make it behave as it should, right down to adding a piece of plastic to rub against a flywheel gear in order to produce the perfect high-pitched sound, not to forget the inclusion of the flywheel itself to make the turbine blades gradually slow down once the motor’s been turned off. For the N1 gauge (fan speed gauge) he built up his own generator around the motor shaft, sending the output through rectifying diodes to a voltmeter.

But the most delightful of all has to be the mechanical linkages for the controls. The controls consist of an Engine Start switch, Fuel Control switch and a throttle lever and are all built around a rheostat which controls the motor speed. The linkages are not pretty, but you have to admire his cleverness and just-go-for-it attitude. He must have done a lot of head scratching while getting it to all work together. We especially like how flipping the Fuel Control switch from cutoff to run levers the rheostat with respect to its dial just a little, to give a bit of extra power to the engine. See if you can puzzle it out in his Part 3 video below where he removes the cover and walks through it all.

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16-Cylinder Stirling Engine Gets a Tune Up

Tiny catapults, kinetic sculptures, a Newton’s Cradle — all kinds of nifty toys can adorn the desk of the executive in your life. On the high end of the scale, a 16-cylinder butane-powered Stirling engine makes a nice statement, but when it comes equipped with a propeller that looks ready for finger-chopping, some mods might be in order before bestowing the gift.

We don’t knock [JohnnyQ90] for buying a rotary Stirling engine from one of the usual sources rather than building, of course. With his micro Tesla turbine and various nitro-powered tools, he’s proven that he has the machining chops to scratch-build one of these engines. And it wasn’t just the digit dicing potential of the OEM engine that inspired him. There was a little too much slop in the bearings for his liking, so he machined a new bearing block and shaft extension. With a 3D-printed shroud, a small computer fan, and snappy brass nose cone, the engine started looking more like a small jet engine. And the addition of a pulley and a small generator gave the engine something interesting to do. What’s more, the increased airflow over the cold end of the engine boosted performance.

Need the basics of Stirling engines? Here’s a quick look at the 200-year history of these remarkable devices.

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