A Cornucopia of High Voltage Sources

Having hacked away with high voltage for many years I’ve ended up using a large number of very different high voltage sources. I say sources and not power supplies because I’ve even powered a corona motor by rubbing a PVC pipe with a cotton cloth, making use of the triboelectric effect. But while the voltage from that is high, the current is too low for producing the necessary ion wind to make a lifter fly up off a tabletop. For that I use a flyback transformer and Cockcroft-Walton voltage multiplier power supply that’s plugged into a wall socket.

So yes, I have an unorthodox skillset when it comes to sourcing high voltage. It’s time I sat down and listed most of the power sources I’ve used over the years, including a bit about how they work, what their output is like and what they can be used for, as well as some idea of cost or ease of making. The order is from least powerful to most powerful so keep reading for the ones that really bite.

Triboelectric Effect

Triboelectric series table
Triboelectric series table

You’ve no doubt encountered this effect. It’s how your body is charged when you rub your feet on carpet and then get a shock from touching a door knob. When you rub two specific materials together there’s a transfer of electrons from one to the other. Not just any two materials will work. To find out which materials are good to use, have a look at a triboelectric series table.

Materials that are on the positive end of the table will become positively charged when rubbed against materials on the negative end of the table. Those materials will become negatively charged. The further apart they are in the table, the stronger the charging.

Powering corona motor with triboelectricity
Powering corona motor with triboelectricity

An example of where I’ve used this is to power the corona motor shown here. I vigorously rub a PVC pipe with a cotton cloth, and as the pipe emerges from the cloth, a sharp wire a few millimeters away takes the charge from the pipe. You can see this corona motor being powered by other power sources in the video here.

This would be considered an electrostatic power source because charge is accumulated on surfaces. Being insulating materials, that charge can’t move around.

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How to Have a Beer with Every Electronics Person

This has got to be the ultimate name-dropping post. I’m tempted just to make a list. Or perhaps it should be like Jeopardy, I’ll list the products or companies and you guess who was there. I am of course talking about the Hackaday Bay Area Maker Faire Meetup last Saturday which started off as a steady stream of Faire-weary exhibitors and suddenly the place was packed to the gills. Luckily we have some photographic evidence of the awesome.

Peter Jansen seen on the right
Peter Jansen seen on the right

If you do something three times you can start saying “always”, right? We always host a meetup on the Saturday night of Bay Area Maker Faire at O’Neill’s Irish Pub in San Mateo. It’s our kind of atmosphere: just enough room to set up hacks you tote along with you, they have Guinness, Lagunitas, and a few in-betweens on tap, you can bring in food from the various eateries that border the bar, and the staff is beyond awesome.

Despite my threat to call-out everyone by name, I’ll keep it to a minimum. It was most excellent meeting Peter Jansen who created the Open Source Science Tricorder, fourth place winner of the Hackaday Prize in 2014. I was glad to see Windell Oskay of Evil Mad Scientist Laboratories there since both Windell and Peter are Ph.D. Physicists. Of course it ended up they are able to converse with regular people too.

In the back Erick Schlaepfer was showing off his MOnSter6502 — check out the interview I did with him about it the day before. Astute readers will recognize who he’s showing that to: Hackaday Editor Emeritus Caleb Kraft stopped by on his way to the MAKE staff party. Somehow, although we shared a beer, neither of us thought of taking a picture together — perpetuating the mythos that Caleb is the Tyler Durden to my Tyler Durden. Incidentally, if anyone knows Chuck Palahniuk (or if he reads Hackaday which would be killer) we’d love to have him speak at SuperCon. Email me.

Also on the ‘didn’t get pictures of’ list is Anouk Wipprecht who stopped by later in the evening. I love her work and it was really great to meet her. Oops, and I’m not supposed to be dropping names. Paul Stoffregen (talking to Gerrit Coetzee and me in the bottom left corner of the image at the top of this post). Okay, enough of that.

There seemed to be a critical mass of Amp Hour elites on the scene. I grabbed this image from Chris Gammell’s Twitter. He snapped a still of Tony Long, Alan Yates, and Jeff Keyzer who have all been on the show (or hosted it). Karl Bowers, host of The Spark Gap podcast, photobombs on the left.

This barely brushes the tip of the iceberg. But I figure you get tired of hearing me prattle on. If you attended I’d love to see the photos you snapped, please link them in the comments below. And of course, if you do still want to play name-that-geek-celeb the comments are the place for it.

Thanks to Rich Hogben for taking all of these great photos and posting them up on Hackaday.io. I’d also like to thank Supplyframe for picking up everyone’s first round of drinks that night. Maker Faire has ended, but this evening will always have a special place in my heart. We look forward to seeing everyone there next year!

WTF is Degaussing?

The modern office has become a sea of LCD monitors. It’s hard to believe that only a few years ago we were sitting behind Cathode Ray Tubes (CRTs). People have already forgotten the heat, the dust, and the lovely high frequency squeal from their flyback transformers.

Image by Søren Peo Pedersen via wikipedia
Image by Søren Peo Pedersen via wikipedia

There was one feature of those old monitors which seems to be poorly understood. The lowly degauss button. On some monitors it was a physical button. On others, it was a magnet icon on the On Screen Display (OSD). Pressing it rewarded the user with around 5 seconds of a wavy display accompanied by a loud hum.

But what exactly did this button do? It seems that many never knew the purpose of that silly little button, beyond the light-and-sound show. The truth is that degaussing is rather important. Not only to CRTs, but in many other electronic and industrial applications.

 

Of Shadow Masks and Aperture Grilles

Close up of a shadow mask by Rauenstein via Wikipedia
Close up of a shadow mask by Rauenstein via Wikipedia

A CRT has quite a few components. There are three electron guns as well as steering and convergence coils at the rear (yoke) of the tube. The front of the tube has a phosphor-coated glass plate which forms the screen. Just behind that glass is a metal grid called the shadow mask. If you had enough money for a Sony screen, the shadow mask was replaced by the famous Trinitron aperture grille, a fine mesh of wires which performed a similar function. The shadow mask or aperture grille’s  job is to ensure that the right beams of electrons hit the red, green, or blue phosphor coatings on the front of the screen.

This all required a very precise alignment. Any stray magnetic fields imprinted on the mask would cause the electron beams to bend as they flew through the tube. Too strong a magnetic field, and your TV or monitor would start showing rainbows like something out of a 1960’s acid trip movie. Even the Earth’s own magnetic field could become imprinted on the shadow mask. Simply turning a TV from North to East could cause problems. The official term for it was “Color Purity”.

magnet-trickThese issues were well known from the early days of color TV sets. To combat this, manufacturers added a degaussing coil to their sets. A coil of wire wrapped around the front of the tube, just behind the bezel of the set. When the set was powered on, the coil would be fed with mains voltage. This is the well-known ‘fwoomp and buzz’ those old TV sets and monitors would make when you first turned them on. The 50 Hz or 60 Hz AC would create a strong moving magnetic field. This field would effectively erase the imprinted magnetic fields on the shadow mask or aperture grille.

Running high current through the thin degaussing coil would quickly lead to a fire. Sets avoided this by using a Positive Temperature Coefficient (PTC) thermistor in-line with the coil. The current itself (or a small heating coil) would heat up the PTC, causing resistance to increase, and current through the coil to drop. After about 5 seconds, the coil was completely shut down, and the screen was (hopefully) degaussed.

As time went on monitors became embedded systems. The PTC devices were replaced by transistors controlled by the monitor’s main microcontroller. Monitor manufacturers knew that their sets were higher resolution than the average TV set, and thus even more sensitive to magnetic fields. Users are also more likely to move a monitor while using it. This lead the manufacturers to add a degauss button to the front of their sets. A push of the button would energize the coil for a few seconds under software control. Some monitors would also limit the number of times a user could push the button, ensuring the coil didn’t get too hot.

Holding a magnet near the front of a black and white (or a monochrome ‘green screen’) CRT created visible distortion, but no lasting damage. Mid-century hackers who tried the same trick with their first color TV quickly learned that the rainbow effect stayed long after the magnet was moved away. In extreme cases like these, the internal degaussing coil wouldn’t be strong enough to clear the shadow mask.

Commercial degaussing coil
Commercial degaussing coil

When all else failed, a handheld degaussing coil or wand could be used. Literally waving the magic wand in front of the screen would usually clear things up. It was of course possible to permanently damage the shadow mask. Back in 2007, I was working for a radar company which had been slow to switch to LCD monitors. Being a radar shop, we had a few strong magnetron magnets lying around. One of these magnets was passed around among the engineers. Leaving the magnet under your monitor overnight would guarantee rainbows in the morning, and a shiny new LCD within a few days.

1024px-RMS_Queen_Mary_20Jun1945_NewYork
Queen Mary, showing her degaussing coil

CRTs aren’t the only devices which use degaussing coils. The term was originally coined in 1945 by Charles F. Goodeve of the Royal Canadian Naval Volunteer Reserve (RCNVR). German mines were capable of detecting the magnetic fields in a naval ship’s steel hull. Coils were used to mask this field. The Queen Mary is one of the more famous ships fitted with a degaussing coil to avoid the deadly mines.

Even mechanical wristwatches can benefit from a bit of degaussing. A watch which has been magnetized will typically run fast. Typically this is due to the steel balance spring becoming a weak magnet. The coils of the spring stick together as the balance wheel winds and unwinds each second. A degaussing coil (or in this case, more properly a demagnetizer) can quickly eliminate the problem.

A story on degaussing wouldn’t be complete without mentioning magnetic media. Handheld or tabletop degaussing coils can be used to bulk erase floppy disks, magnetic tape, even hard disks. One has to wonder if the degaussing coils in monitors were responsible for floppy disks becoming corrupted back in the old days.

So there you have it. The magic degaussing button demystified!

Hacking for Good: Watly

Here at Hackaday, we often encourage people to hack for the greater good through contests. Sure, it is fun to create a wireless barbeque thermometer or an electronic giant foam finger. At the end of the day, though, those projects didn’t really change the world, or maybe they just change a little corner of the world.

I recently saw a commercial device that made me think about how more hacker-types (including myself) ought to be working more on big problems. The device was Watly. The Italian and Spanish start up company claims the car-sized device is a “solar-powered computer.” No offense to them, but that’s the worst description for Watly that you could pick and still be accurate.

So what is Watly? It looks like some sort of temporary shelter or futuristic campsite equipment. However, it contains an array of solar cells and a very large battery. I know you are thinking, “Great. A big solar charger. Big deal.” But there’s more to Watly then just that.

The first Watly rolled out in Ghana, in Sub-Saharan Africa. About 67% of the population there–over 600 million people–do not have electricity. Nearly 40% do not have safe water. Watly uses a graphene-based filter and then uses its electricity to distill safe drinking water by boiling it. The company claims the device can deliver about 5,000 liters of safe drinking water per day.

If you read Hackaday, it is a good bet you have easy access to safe drinking water, electricity, and Internet. Think for a minute what it would be like if you didn’t. Here on the Gulf Coast of the United States, we sometimes have hurricanes or other storms that show us what this is like for a week or two. But even then, people come with water in trucks or cans. Generators show up to let you run your fridge for a few hours. Even more important: you know the situation is only temporary. What if you really thought those services would never be restored?

The portable device can provide power, water, and wireless Internet service and can last for 15 years. Watly intends to create a larger version with even more capacity.  The project received funding from the EU Horizon 2020 program that we’ve mentioned before. Creating clean water is something that can help lots of people. So is using less water. If you want some more inspiration for tackling water problems, we’ve got some links for you.

Symmetry for Beginners – The Rubik’s Cube

Symmetry is everywhere in our natural world. Just take a look at your hands, a butterfly, or a sunflower.  It’s easy to pass off the idea of symmetry and symmetric structures as a simple quirk of existence, and to pay it little mind. If this is your view, I can assure you it will no longer be by the end of this series. If we force ourselves to look beyond the grade school applications of symmetry, we find a world rich in connections via many different types of symmetric identities. One of the most interesting is Gauge Symmetry, which lies at the heart of Quantum Electrodynamics, or QED (we’ll get into this a bit later in the series). Several branches of higher level mathematics study symmetry in detail, allowing a host of sciences, from physics to chemistry,  to view difficult problems and theories from a different perspective.

The subject matter of the ideas explored in symmetry is complicated, and not well known outside of academia and the theoretical sciences. It is the goal of this series of articles to simplify some of the concepts that underpin the study of symmetry, so that the average hacker can gain a basic (and I mean basic) understanding of this fascinating body of knowledge, and put it to use in future projects.  We’ll start things off by taking a look at a machine that has crossed the Hackaday server many times – those nifty Rubik’s Cube solvers. Just how do those things work anyway?

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Relive the Hackaday Belgrade Conference

The Hackaday Belgrade Conference was an amazing success. For proof, you need look no farther than the slate of talks that we have been publishing over that past several weeks. Each looks at different angles of the hardware universe; what does it mean to create hardware, where have we been, where are we going, and where does inspiration for the next great design come from?

The talks have now all been published and collected into one video playlist; it was an intense day of talks all caught in one streaming frenzy. But if you can’t make it through in one sitting, I’ve also listed the individual talks after the break so you that you may pick and choose.

There are, however, two talks that have just been published this afternoon. These are the opening remarks presented by Aleksandar Bradic and the closing remarks which I presented. When we meet people we’re often asked about what is going on behind the scenes. It’s really easy to think that nobody cares about what it takes to pull together a conference, run an amazing engineering challenge, or how we decide what we think matters when looking to the future. Alek covers the back story of how Supplyframe and Hackaday came together, as well as what led us to choose Belgrade for this conference. I discuss what I think is a core virtue of Hackaday; the free and open sharing of information and ideas. It’s a concept I believe in, and the most noble of reasons for documenting your work so that others may build upon your knowledge and skill.

Hackaday | Belgrade went beyond what we even considered possible. It joins the 2016 SuperConference (whose talk videos have also been published) as a shining example of our strong, active, and engaged community who want to spend their time enabling everyone — hackers, designers, and engineers alike — to succeed.

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Hackaday Links: May 22, 2016

Lulzbot’s TAZ 6 has been released. Lulzbot’s printers consistently place in the top three of any 3D printing list, and the TAZ 6 will likely be no exception. [James Bruton] was one of the lucky ones who got a review unit, and first looks are promising. The TAZ 6 has the auto bed leveling found in the Lulzbot Mini, and a ‘power tower’ for all the electronics. There are completely unconfirmed rumors (or someone told me and I forgot who) that the power tower will be available separately at some point.

The most impressive circuit we’ve seen this week month year is the dis-integrated 6502. It’s a discrete 6502 CPU, about a square foot in size. It’s slow, but it works. RAM and ROM is easy to make embiggened, which means someone needs to build a dis-integrated 6522 VIA. Who’s game?

[Jeremy Cook] wanted to learn another CAD package, in this case Onshape. Onshape is the ‘first cloud-only CAD package’, which has one huge bonus – you can run it anywhere, on anything – and one huge minus – it’s in the cloud. He designed a bicycle cupholder.

Last week, several thousand Raspberry Pi Zeros shipped out to retailers in the US and UK. For a time, Pi Zeros were in stock in some online stores. Now? Not so much. Where did they all go? eBay, apparently. It’s called arbitrage, and it’s the only risk-free form of investment.

Remember those ‘bed of nails’ toys, that were basically two sheets of plastic, with hundreds of small pins able to make 3D impressions of your face and hands. No, there is no official name for these devices, but here’s a Kickstarter for a very clever application of these toys. You can use them to hold through hole parts while soldering. Brilliant.

You should not pay attention to 3D printers on Kickstarter. Repeat after me: you should not give money to 3D printers on Kickstarter. Here’s a 3D printer on Kickstarter, promising a 3D printer for $74. I own several hats, and will eat one if this ships by next year.

Remember bash.org? It’s being reimplemented on hackaday.io.