Arduino Controlled Dahlander Motor Switch

 

Dahlander Switch

[Jean-Noel] is fixing a broken Lurem woodworking machine. This machine uses a three-phase Dahlander motor, which has three operation modes: stop, half speed, and full speed. The motor uses a special mechanical switch to select the operating mode. Unfortunately, the mechanical bits inside the switch were broken, and the motor couldn’t be turned on.

To solve the problem without sourcing a new switch, [Jean-Noel] built his own Arduino based Dahlander switch. This consists of three relays that select the wiring configuration for each speed mode. There’s also a button to toggle settings, and two lamps to show what mode the motor is currently in.

The Arduino runs a finite-state machine (FSM), ensuring that the device transitions through the modes in the correct order. This is quite important, since the motor could be damaged if certain restrictions aren’t followed. The state machine graph was generated using Fizzim, a free tool that generates not only FSM graphs, but also Verilog and VHDL code for the machines.

The final product is housed in a DIN rail case, which allows it to be securely mounted along with the rest of the wiring. The detailed write-up on this project explains all the details of the motor, and the challenges of building this replacement switch.

Rebuilding A 50,000 Volt Power Supply

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The theory behind building power supplies is relatively easy, but putting it into practice and building a multi-kilovolt supply is hard. A big transformer in air will simply spark to itself, turning what could be something very cool into something you just don’t want to be around. [glasslinger] over on YouTube is an expert at this sort of thing, as shown in his 50,000 Volt power supply build. That’s a 55 minute long video, and trust us: it’s worth every minute of your time.

[glasslinger] began his build by taking an old 15,000 Volt neon sign transformer and repurposing the coils and cores for his gigantic 50,000 volt transformer. There was a small problem with this little bit of recycling: the neon sign transformer was potted with tar that needed to be removed.

To de-pot the transformer, [glasslinger] made a small oven from a helium tank, melting all the goo out with an old school gasoline torch. From there, hours and hours of cleaning ensued.

The transformer cores were cleaned up and cut down, and a new primary wound. A small-scale test (shown above) using the old secondaries resulted in a proof of concept with some very large sparks. The next step was putting the entire transformer in a box and filling it with transformer oil.

The money shot for this build comes when [glasslinger] assembles his transformer, rectifier, and all the other electronics into a single, surprisingly compact unit and turns standard wall power into a 50,000 Volt spark. You can literally smell the ozone from the video.

 

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Adventures In Hackerspacing: An Interview with Chris Boden of The Geek Group

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There are some big hackerspaces out there.
And then there’s The Geek Group.
It takes a certain chutzpah to convert a 43,000 foot former YMCA into a hackerspace. And an epic hackerspace it is, complete with 5 axis CNC machines, 3d printers, and of course, giant robots romping through a forest of Tesla coils.  The Geek Group has performed live demos in front of thousands of people over the years, and inspired tens of thousands more via the internet. You don’t work this big without having some big adventures, and The Geek Group is no exception. They’ve been through roof leaks, gas pipe breaks, surprise tax bills and angry neighbors. They’ve also been dealing with their current adventure, fire.

Unless you’ve been under a rock the last few weeks, you’ve probably read about the recent fire, and ensuing cleanup at The Geek Group labs. We’ve covered the fire and its cause here on Hackaday, with no small amount of drama in our comments section. There is a small but vocal minority who don’t have many good things to say. Accusations of cults, safety violations, and tax evasion often fly. While some groups would take this lying down, the geek group put on their flame proof suits and wade through the comments. None more vocally than [Chris Boden], the president, CEO and founder.

DISCLAIMER: The interview contains questionable content and some profanity (which we’ve altered as grawlix). We have posted the transcript as it was captured, which includes some spelling and grammar issues. Please consider these things before clicking through to the interview itself.

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Producing Ozone at 3500 RPM

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Motors are fun, and high voltage even more so. We’re guessing that’s what went through [brazilero2008]‘s mind when he put together an electrostatic motor using upcycled parts he found lying around.

The electrostatic rotor works by connecting a very high voltage, low current power supply – in this case an industrial air ionizer – to a set or rotors surrounding a plastic rotor. The hot electrodes spray electrons onto the rotor, which are picked up by the ground electrodes. If the system doesn’t arc too much, you have yourself a plastic rotor that spins very, very fast.

[brazilero]‘s device is made out of an aluminum turkey pan, a few acrylic tubes, and a few cardboard disks; all stuff you can find in a well-stocked trash can. After completing the device, it was taken apart and finished and screwed onto a beautiful painted jewelry box. Very cool for something you can make out of trash, and dangerous enough to be very interesting.

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Do It Yourself Nuclear Fusion

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By far the coolest projects we see are those dealing with high voltages and deep vacuums. Vacuum tubes of all types fall into this category, as do the electron microscopes we see from time to time. The king of all vacuum and electron hacks is the Farnsworth Fusor, a machine that will both transmute the elements and bathe you in neutrons. Fun stuff, and [Daniel] has a great tutorial for building your own.

[Dan]‘s fusor is surprisingly simple to make. Obviously, the most important part is the vacuum chamber which in this build is based around a glass oil cup cylinder. With just a few roughly machined parts – the only tool needed to make the metal plates is a drill press – it can hold a low enough vacuum to contain a star in a jar.

For reasons of safety and sanity, [Dan] isn’t running his fusor at a high enough voltage to actually fuse deuterium into helium. This is really just a beautiful, glowey demonstration of what can be done with enough knowledge, the skills, and a handful of parts.

“Professor Kill A. Volt” Shocks Pumpkins with his Tesla Coil

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[JJ Dasher] is back again this year, shocking some pumpkins! (Volume warning). We featured [JJ] two years ago for his Halloween candy shocking Tesla coil. He apparently has been busy in his mad scientist laboratory doing some upgrades. This year his coil is producing 5 foot long streaming arcs!

[JJ's] Tesla coil is a uses two microwave oven transformers as a power supply. He also uses an Asynchronous Rotary Spark Gap (ASRG). As the name implies, a rotary spark gap uses a motor to turn a rotor. At certain points in the rotation, the rotor creates a small enough gap that a high voltage spark can jump across, energizing the primary coil. This idea is similar to an automotive ignition system distributor. [Pete] gives a great example of an ASRG in this video. Most ASRG based Tesla coils use the small motor to spin up the spark gap. Varying the speed of the motor creates the characteristic “motor revving” noise heard in the final arcs of the Tesla Coil.

[JJ] made things a bit more interesting by installing a couple of fluorescent bulbs inside a pumpkin near the coil. The coil lights them easily, and they glow even brighter when the pumpkin is struck. Still not satisfied, he also donned his grounded chainmail gloves and drew the arc to himself. We always love seeing people safely taking hits from massive Tesla coils, but this definitely falls under the “don’t try this at home” banner.

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A Much More DYI Air Gap Flash Unit

In reaction to the other air gap flash unit we featured a few days ago, [Eirik] sent us a tip about another one he recently made. In his setup, the duration of the flash peak intensity is around 300ns (1/3,333,333 of a second). As a reminder, an air flash unit consists of a circuit charging a high voltage capacitor, a circuit triggering a discharge on demand, a high voltage capacitor and the air flash tube itself. The flash tube contains two wires which are separated just enough to not spark over at max potential. Isolated from the other two, a third wire is placed in the tube. This wire is connected to a trigger/pulse transformer, which will ionize the gap between the two capacitor leads. This causes the gap to breakdown and a spark to form, thereby creating a flash of light.

[Eirik] constructed his flash tube using an olive jar and a glass test tube. As you can see from the (very nice) picture above, the spark travels along the glass test tube, making the quenching much faster than in an open air spark. [Eirik] built his own high voltage capacitor, using seven rolled capacitors of roughly 2nF each made with duct-tape, tin foil and overhead transparencies. For ‘safety’ they are stored in a PP-pipe. A look at the schematics and overall circuit shown on the website reveals how skilled [Eirik] is, making us think that this is more a nice creation than a hack.

Disclaimer: As with the previous airgap flash, high voltages are used here, so don’t do this at home.