Big Power, Little Power, Tiny Power, Zap!

August 9, 2018 by Roger Cheng 4 Comments

Our Hackaday Prize Challenges are evaluated by a panel of judges who examine every entry to see how they fare against judging criteria. With prize money at stake, it makes sense we want to make sure it is done right. But we also have our Hackaday Prize achievements, with less at stake leading to a more free-wheeling way to recognize projects that catch our eye. Most of the achievements center around fun topics that aren’t related to any particular challenge, but it’s a little different for the Infinite Improbability achievement. This achievement was unlocked by any project that impressed with their quest for power, leading to some overlap with the just-concluded Power Harvesting Challenge. In fact, when the twenty Power Harvesting winners were announced, we saw that fourteen of them had already unlocked the achievement.

Each of the Power Harvesting winners will get their own spotlight story. And since many of them have unlocked this achievement, now is the perfect time to take a quick tour through a few of the other entries that have also unlocked the Infinite Improbability achievement.

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How A Van De Graaff Generator Works

February 16, 2017 by Steven Dufresne 41 Comments

What I particularly like about the Van de Graaff (or VDG) is that it’s a combination of a few discrete scientific principles and some mechanically produced current, making it an interesting study. For example, did you know that its voltage is limited mostly by the diameter and curvature of the dome? That’s why a handheld one is harmless but you want to avoid getting zapped by one with a 15″ diameter dome. What follows is a journey through the workings of this interesting high voltage generator.

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High Voltage Please, But Don’t Forget The Current

June 8, 2016 by Steven Dufresne 30 Comments

In high voltage applications involving tens of thousands of volts, too often people think about the high voltage needed but don’t consider the current. This is especially so when part of the circuit that the charge travels through is an air gap, and the charge is in the form of ions. That’s a far cry from electrons flowing in copper wire or moving through resistors.

Consider the lifter. The lifter is a fun, lightweight flying machine. It consists of a thin wire and an aluminum foil skirt separated by an air gap. Apply 25kV volts across that air gap and it lifts into the air.

Lifter flying with high voltage power supply

Lifter parts

So you’d think that the small handheld Van de Graaff generator pictured below, that’s capable of 80kV, could power the lifter. However, like many high voltage applications, the lifter works by ionizing air, in this case ionizing air surrounding the thin wire resulting in a bluish corona. That sets off a chain of events that produces a downward flowing jet of air, commonly called ion wind, lifting the lifter upward.

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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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Power From Paper

February 2, 2016 by Al Williams 26 Comments

Comedian Steven Wright used to say (in his monotone way):

“We lived in a house that ran on static electricity. If we wanted to cook something, we had to take a sweater off real quick. If we wanted to run a blender, we had to rub balloons on our head.”

Turns out, all you need to generate a little electricity is some paper, Teflon tape and a pencil. A team from EPFL, working with researchers at the University of Tokyo, presented just such a device at a MEMS conference. (And check out their video, below the break.)

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Retro Video Games Sounds…for Your Toilet

June 6, 2011 by Mike Nathan 10 Comments

super_mario_toilet

After reading about a Super Mario Brothers themed bathroom, [Jonathan] decided that it would be pretty cool to have his toilet play the “warp pipe” sound whenever anyone flushed.

He grabbed a small sound drop key chain on eBay and disassembled it to see how things worked. Once he figured out which solder pads corresponded to the warp pipe sound he added a few wires that, when shorted, trigger the sound effect.

He debated as to how the sound generator should be wired to the toilet, and was pretty reluctant to place the key chain inside the tank due to concerns about sound volume and water damage. He ultimately decided to trigger the sound effects using triboelectric charge, much like those touch lamps from the ’80s. He rigged up a simple circuit that is connected to both the toilet handle as well as the water intake valve on the wall. When someone touches the handle, the small charge that is present in their hand triggers the sound effect as you can see in the video below.

Instead of using a standard project box, he opted to build a small warp tube replica from cardboard and paper, which really brings everything together nicely.

While he says that the circuit is pretty sensitive, triggering at odd times or not at all, we still think it’s awesome.

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