Arc from a flyback transformer power supply

A Cornucopia Of High Voltage Sources

May 26, 2016 by Steven Dufresne 39 Comments

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

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

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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Raspberry Pi Cluster Build Shows How And What

May 26, 2016 by Richard Baguley 36 Comments

Raspberry Pi clusters are a dime a dozen these days. Well, maybe more like £250 for a five-Pi cluster. Anyway, this project is a bit different. It’s exquisitely documented.

[Nick Smith] built a 5-node Pi 3 cluster from scratch, laser-cutting his own acrylic case and tearing down a small network switch to include in the design. It is, he happily admits, a solution looking for a problem. [Smith] did an excellent job of documenting how he designed the case in CAD, prototyped it in wood, and how he put the final cluster together with eye-catching clear acrylic.

Of interest is that he even built his own clips to hold the sides of the case together and offers all of the files for anyone who wants to build their own. Head over to his page for the complete bill of materials (we didn’t know Pis were something you could order in 5-packs). And please, next time you work on a project follow [Nick’s] example of how to document it well, and how to show what did (and didn’t) work.

If 5 nodes just doesn’t do it for you, we suggest this 120-node screen-equipped monster, and another clear-acrylic masterpiece housing 40 Pis. This stuff really isn’t only for fun and games. Although it wasn’t Pi-based, here’s a talk at Hackaday Belgrade about an ARM-based SBC cluster built to crunch numbers for university researchers.

Flame Triodes Don’t Need Any Vacuum

May 26, 2016 by Jenny List 37 Comments

There is a rich history surrounding the improvisation of electronic components. From cats-whisker foxhole radio detectors using razor blades through radio amateurs trying antique quartz lenses as crystal resonators and 1950s experimenters making their own point-contact transistors, whenever desirable components have been unavailable the ingenuity of hackers and makers has always sought to provide.

In an age when any component you might wish for is only a web browser and a courier package away, you might think there would be no need for such experiments. But it is in our curious nature to push the boundaries of what can be made without a factory at our disposal, so there are still plenty of ingenious home-made components under construction.

One such experiment came our way recently. It’s a few years old, but it’s a good one. [Nyle Steiner, K7NS] made a working triode without any form of vacuum, instead its medium is a flame. He’s demonstrated it as a rectifier, amplifier, and oscillator, and while it might not be the best triode ever it’s certainly one of the simplest.

In a traditional vacuum triode the current flows as electrons released from a hot cathode and are able to cross the space because there are no gas molecules for them to collide with. The flame triode has an abundance of gas, but the gasses within it and its immediate surroundings are also strongly ionized, and thus electrically conductive. Flame ionization detectors have exploited this phenomenon in scientific instruments for a very long time.

A roaring flame might not be the most practical thing to keep in your electronic equipment, but [Nyle]’s experiment is nonetheless an impressive one. He’s posted a video showing it in action, which you can see below the break.

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Hackaday Prize Entry: Robotic Prosthetic Leg Is Open Source And 3D-Printable

May 25, 2016 by Moritz Walter 19 Comments

We’ve been 3D-printing parts for self-replicating machines before, but we’ve been working on the wrong machines. Software and robotics engineer [David Sanchez Falero] is about to set it right with his Hackaday Prize entry, a 3D-printable, open source, robotic prosthetic leg for humans.

[David] could not find a suitable, 3D-printable and customizable prosthetic leg out there, and given the high price of commercial ones he started his own prosthesis project named Drakkar. The “bones” of his design are made of M8 steel threaded rods, which help to keep the cost low, but are also highly available all over the world. The knee is actively bent by a DC-motor and, according to the source code, a potentiometer reads back the position of the knee to a PID loop.

While working on his first prototype, [David] quickly found that replicating the shape and complex mechanics of a human foot would be too fragile when replicated from 3D-printed parts. Instead, he looked at how goat hooves managed to adapt to uneven terrain with only two larger toes. All results and learnings then went into a second version, which now also adapts to the user’s height. The design, which has been done entirely in FreeCAD, indeed looks promising and might one day compete with the high-priced commercial prosthesis.

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Smart AC Monitoring: Without The $500 Price Tag

May 25, 2016 by Al Williams 8 Comments

[Tisham Dhar] has been interested in monitoring AC power and previously built a breakout board for the ADE7763. He wanted to find something cheaper and more modern. The ATM90E26 fit the bill. It can communicate via a UART or SPI, and has multiple metering modes. The problem? The evaluation module from Atmel costs about $500 (and for [Dhar] $800 Australian), although the part itself can be had for under a buck in bulk. (Atmel even sent him three samples for free.)

[Dhar] put the low voltage components from the reference design on a PCB and pocketed the difference in cost. So far, he’s tested the setup with a Teensy and low voltage measurements only. He plans to do a full test soon.

The test setup uses SPI mode 3 to talk to the processor. You can find the relevant code on GitHub.

We see a lot of energy monitoring projects go by. Of course, working on household wiring current can be dangerous, so be careful out there.

Building A Flamethrower Guitar To Really Rock Out With

May 25, 2016 by James Hobson 38 Comments

Everyone’s favorite safety-tie-wearing-eccentric-inventor, [Colin Furze], is back at it again, this time making a flamethrower guitar — sponsored by Intel!?

As an ex-plumber, [Furze] is a master fabricator, and he’s brought many amazing mechanical inventions to life. In this video, perhaps for the first time, he’s integrated an Intel Curie Arduino in it, for a bit more fine control.

He’s hacked apart a couple of propane blow-torches, milled and lathed his own fittings and manifolds, and even TIG welded together a pressure vessel for the fuel — kids, do not try this at home!

The two blowtorches act as pilot lights for a third gas supply line to make the big firing explosion — the plan for the Arduino? To blast off the fire at certain parts during the song, add timing, or even just set up some cool patterns.

Did we mention he’s also got his own custom propane fueled guitar amp to go with it??

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Learn Functional Reactive Programming On Your Arduino

May 25, 2016 by Elliot Williams 49 Comments

Everyone loves learning a new programming language, right? Well, even if you don’t like it, you should do it anyway, because thinking about problems from different perspectives is great for the imagination.

Juniper is a functional reactive programming language for the Arduino platform. What that means is that you’ll be writing your code using anonymous functions, map/fold operations, recursion, and signals. It’s like taking the event-driven style that you should be programming in one step further; you write a=b+3 and when b changes, the compiler takes care of changing a automatically for you. (That’s the “reactive” part.)

If you’re used to the first-do-this-then-do-that style of Arduino (and most C/C++) programming, this is going to be mind expanding. But we do notice that a lot of microcontroller code looks for changes in the environment, and then acts (more or less asynchronously) on that data. At that level of abstraction, something like Juniper looks like a good fit.