Pushing The Plasma Limits With A Custom Flyback Transformer

October 22, 2024 by Danie Conradie 11 Comments

For serious high-voltage plasma, you need a serious transformer. [Jay Bowles] from Plasma Channel is taking his projects to the next level, so he built a beefy 6000:1 flyback transformer.

[Jay] first built a driving circuit for his dream transformer, starting with a simple 555 circuit and three MOSFETs in parallel to handle 90 A of current. This led to an unexpected lesson on the necessity for transistor matching as one of them let out the Magic Smoke. On his second attempt, the 555 was swapped for an adjustable pulse generator module with a display, and a single 40 A MOSFET on the output.

The transformer is built around a large 98×130 mm ferrite core, with eleven turns on the primary side. All the hard work is on the secondary side, where [Jay] designed a former to accommodate three winding sections in series. With the help of the [3D Printing Nerd], he printed PLA and resin versions but settled on the resin since it likely provided better isolation.

[Jay] spent six hours of quality time with a drill, winding 4000 feet (~1200 m) of enameled wire. On the initial test of the transformer, he got inch-long arcs on just 6 V and 15 W of input power. Before pushing the transformer to its full potential, he potted the secondary side in epoxy to reduce the chances of shorts between the windings.

Unfortunately, the vacuum chamber hadn’t removed enough of the air during potting, which caused a complete short of the middle winding as the input started pushing 11 V. This turned the transformer into a beautiful copper and epoxy paperweight, forcing [Jay] to start again from scratch.

On the following attempt [Jay] took his time during the potting process, and added sharp adjustable electrodes to act as voltage limiters on the output. The result is beautiful 2.25-inch plasma arcs on only 11 V and 100 W input power. This also meant he could power it with a single 580 mAh 3S LiPo for power.

[Jay] plans to use his new transformer to test materials he intends to use in future plasma ball, ion thruster, and rail gun projects. We’ll be keeping an eye out for those!

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Modular Magnetic LED Matrix

October 15, 2024 by Danie Conradie 5 Comments

[bitluni] seems rather fond of soldering lots of LEDs, and fortunately for us the result is always interesting eye candy. The latest iteration of this venture features 8 mm WS2812D-F8 addressable LEDs, offering a significant simplification in electronics and the potential for much brighter displays.

The previous version used off-the-shelf 8×8 LED panels but had to be multiplexed, limiting brightness, and required a more complex driver circuit. To control the panel, [bitluni] used the ATtiny running the MegaTinyCore Arduino core. Off-the-shelf four-pin magnetic connectors allow the panels to snap together. They work well but are comically difficult to solder since they keep grabbing the soldering iron. [bitluni] also created a simple battery module and 3D printed neat enclosures for everything.

Having faced the arduous task of fixing individual LEDs on massive LED walls in the past, [bitluni] experimented with staggered holes that allow through-hole LEDs to be plugged in without soldering. Unfortunately, with long leads protruding from the back of the PCB, shorting became an immediate issue. While he ultimately resorted to soldering them for reliability, we’re intrigued by the potential of refining this pluggable design.

The final product snapped together satisfyingly, and [bitluni] programmed a simple animation scheme that automatically updates as panels are added or removed. What would you use these for? Let us know in the comments below. Continue reading “Modular Magnetic LED Matrix” →

Levitating Magnet In A Spherical Copper Cage

October 13, 2024 by Danie Conradie 21 Comments

Lenz’s Law is one of those physics tricks that look like magic if you don’t understand what’s happening. [Seth Robinson] was inspired by the way eddy currents cause a cylindrical neodymium magnet to levitate inside a rotating copper tube, so he cast a spherical copper cage to levitate a magnetic sphere.

Metal casting is an art form that might seem simple at first, but is very easy to screw up. Fortunately [Seth] has significant experience in the field, especially lost-PLA metal casting. While the act of casting is quick, the vast majority of the work is in the preparation process. Video after the break.

[Seth] started by designing and 3D printing a truncated icosahedron (basically a low-poly sphere) in two interlocking halves and adding large sprues to each halve. Over a week, the PLA forms were repeatedly coated in layers of ceramic slurry and silica sand, creating a thick shell around them. The ceramic forms were then heated to melt and pour out the PLA and fired at 870°C/1600°F to achieve full hardness.

With the molds prepared, the molten copper is poured into them and allowed to cool. To avoid damaging the soft copper parts when breaking away the mold, [Seth] uses a sandblaster to cut it away sections. The quality of the cast parts is so good that 3D-printed layer lines are visible in the copper, but hours of cleanup and polishing are still required to turn them into shiny parts. Even without the physics trick, it’s a work of art. A 3d printed plug with a brass shaft was added on each side, allowing the assembly to spin on a 3D-printed stand.

[Seth] placed a 2″ N52 neodymium spherical magnet inside, and when spun at the right speed, the magnet levitated without touching the sides. Unfortunately, this effect doesn’t come across super clearly on video, but we have no doubt it would make for a fascinating display piece and conversation starter.

Using and abusing eddy currents makes for some very interesting projects, including hoverboards and magnetic torque transfer on a bicycle.

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Solar Planes Are Hard

October 12, 2024 by Danie Conradie 12 Comments

A regular comment we see on electric aircraft is to “just add solar panels to the wings.” [James] from Project Air has been working on just such a solar plane, and as he shows in the video after the break, it is not a trivial challenge.

A solar RC plane has several difficult engineering challenges masquerading as one. First, you need a solid, efficient airframe with enough surface area for solar panels. Then, you need a reliable, lightweight, and efficient solar charging system and, finally, a well-tuned autopilot to compensate for a human pilot’s limited endurance and attention span.

In part one of this project, a fault in the electrical system caused a catastrophe so James started by benching all the electricals. He discovered the MPPT controller had a battery cutoff feature that he was unaware of, which likely caused the crash. His solution was to connect the solar panels to the input of a 16.7 V voltage regulator—just under the fully charged voltage of a 4S LiPo battery— and wire the ESC, control electronics, and battery in parallel to the output. This should keep the battery charged as long as the motor doesn’t consume too much power.

After rebuilding the airframe and flight testing without the solar system, [James] found the foam wing spars were not up to the task, so he added aluminum L-sections for stiffness. The solar panels and charging system were next, followed by more bench tests. On the test flight, it turned out the aircraft was now underpowered and struggled to gain altitude thanks to the added weight of the solar system. With sluggish control responses,[James] eventually lost sight of it behind some trees, which led to a flat spin and unplanned landing.

Fortunately, the aircraft didn’t sustain any damage, but [James] plans to redesign it anyway to reduce the weight and make it work with the existing power system.

We’ve seen several solar planes from [rctestflight] and meticulously engineered versions from [Bearospace Industrues]. If long flight times is primarily what you are after, you can always ditch the panels and use a big battery for 10+ hour flights.

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Tiny Drones Do Distributed Mapping

October 11, 2024 by Danie Conradie 12 Comments

Sending teams of tiny drones to explore areas and structures is a staple in sci-fi and research, but the weight and size of sensors and the required processing power have long been a limiting factor. In the video below, a research team from [ETH Zurich] breaks through these limits, demonstrating indoor mapping with a swarm of tiny drones without dependence on any external systems.

The drone is the modular Crazyflie platform, which uses stackable PCBs (decks) to expand capabilities. The team added a Flow deck for altitude control and motion tracking, and a Loco positioning deck with a UWB module determining relative distances between drones. On top of this, the team added two custom decks. The first mounts four VL53L5CX 8×8 pixel TOF sensors for omnidirectional LIDAR scanning. The final deck does handles all the required processing with a GAP9 System-on-Chip, which features 10 RISC-V cores running on just 200 mW of power.

Of course the special sauce of this project lies in the software. The team developed a lightweight collaborative Simultaneous Localization And Mapping (SLAM) algorithm which can be distributed across all the drones in the swarm. It combines LIDAR scan data and the estimated position of the drone during the scan, and then overlays the data for the scans for each location across different drones, compensating for errors in the odometry data. The team also implemented inter-drone collision avoidance, packet collision avoidance and optimizing drones’ paths. The code is supposed to be available on GitHub, but the link was broken at the time of writing.

The Crazyflie platform has been around for more than a decade now, and we’ve seen it used in several research projects, especially related to autonomous navigation. Continue reading “Tiny Drones Do Distributed Mapping” →

3D Printed Bearings With Filament Rollers

October 9, 2024 by Danie Conradie 24 Comments

Commodity bearings are a a boon for makers who to want something to rotate smoothly, but what if you don’t have one in a pinch? [Cliff] of might have the answer for you, in the form of 3D printed bearings with filament rollers.

With the exception of the raw filament rollers, the inner and outer race, roller cage and cap are all printed. It would also be possible to design some of the components right into a rotating assembly. [Cliff] makes it clear this experiment isn’t about replacing metal bearings — far from it. Instead, it’s an inquiry into how self-sufficient one can be with a FDM 3D printer. That didn’t stop him from torture testing the design to its limits as wheel bearings on an off-road go-cart. The first version wasn’t well supported against axial loads, and ripped apart during some more enthusiastic maneuvers.

[Cliff] improved it with a updated inner race and some 3D printed washers, which held up to 30 minutes of riding with only minimal signs of wear. He also made a slightly more practical 10 mm OD version that fits over an M3 bolt, and all the design files are downloadable for free. Cutting the many pieces of filament to length quickly turned into a chore, so a simple cutting jig is also included.

Let us know in the comments below where you think these would be practical. We’ve covered some other 3D printed bearing that use printed races, as well as a slew bearing that’s completely printed. Continue reading “3D Printed Bearings With Filament Rollers” →

3D Printed Hydrofoil Goes From Model Scale To Human Scale With Flight Controller

October 6, 2024 by Danie Conradie 5 Comments

Hydrofoils have been around for several decades, but watching a craft slice through the water with almost no wake never get old. In the videos after the break, [rctestflight] showcases his ambitious project: transforming a standup paddleboard into a rideable hydrofoil with active stabilization.

Unlike conventional electric hydrofoil boards that depend on rider skill for balance, [rctestflight] aims to create a self-stabilizing system. He began by designing a small-scale model, complete with servo-controlled ailerons and elevators, dual motors for differential thrust, and a dRehmFlight flight controller. A pair of sonar sensors help the flight controller maintain constant height above the water. The wings are completely 3D printed, with integrated hinges for flight control surfaces slots for wiring and control components. It’s better suited for 3D printing than RC aircraft since it’s significantly less sensitive to weight, allowing for more structural reinforcement. The small scale tests were very successful and allowed [rctestflight] to determine that he didn’t need the vertical stabilizer and rudder.

The full-sized version features a scaled up wing, larger servos and motors attached to an 11-foot standup paddleboard — minus its rear end — mounted on commercially available e-foil booms. A foam battery box stores a hefty LiFePO4 battery, while the electronics from the smaller version are repurposed here. Despite only catching glimpses of this larger setup in action at the end of the video, it promises an excitingly smooth lake ride we would certainly like to experience.

We’ve seen several 3D printed hydrofoils around here, but this promised to be the largest successful attempt. Don’t fail us [Daniel].

Continue reading “3D Printed Hydrofoil Goes From Model Scale To Human Scale With Flight Controller” →