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Unsafe at Any Amperage? Our Dilemma from Volume 09

Unsafe at Any Amperage? Our Dilemma from Volume 09

Yesterday I ran into this web extra from back in 2007 when we were working on MAKE Volume 09, and it brought back some fond memories. We were deep in production, and one of our major slotted projects was the “Antigravity Lifter.” The dilemma was whether to publish this cool but really high-voltage and potentially really dangerous project. Enter the MAKE Advisory Board. Our editor-in-chief Mark Frauenfelder sent a message out to the members of the board, and a lively discussion ensued. We shared the whole thing online.

To give you a little background on lifters, here’s the description that was going to run with the article:

“Lifters (aka ionocraft) are a simple assembly of wire and foil that acts as an asymmetrical capacitor. The thin wire runs parallel to and above a length of aluminum foil, with the two attached and held apart by a lightweight nonconductor such as balsa wood.

When you apply a voltage across the lifter, negative to the wire emitter and positive to foil ground, static charge builds up on both sides. At high voltages, electrons from the wire leak into and ionize the surrounding air molecules — mostly the oxygen, since nitrogen requires more energy to ionize. These negatively charged molecules are pulled downwards into the foil, which has a positive static charge. In this way, the lifter constantly pulls air downward, producing an “ion wind” which results in upward thrust. (Many enthusiasts believe that additional forces also contribute to the lifter effect.) Typical home-built lifters will fly at around 20kV at 0.4 milliamps.

At such high voltages, surplus electrons from the wire can also jump the gap down to the foil directly. This shortcut reduces both the amount of charge that can ionize the air and the force with which the ions are drawn downward. When this happens, energy goes into producing a spark rather than producing lift, so in order to fly, the lifter must be “tuned” to eliminate arcing.

Like air purifiers and electrical storms, lifters generate ozone, nitrous oxide, and other gases which may enhance the invigorating feeling of experimentation.

Many strange and poorly understood phenomena are manifested by high voltages, and some investigators believe that this area has never received the research attention it deserves. Common wisdom attributes this bias to Thomas Edison, who used his considerable influence to steer scientific inquiry and respect away from the high-voltage ideas of his rival Nikola Tesla.”

And here’s the first part of the dilemma discussion:

DANGER: HIGH VOLTAGE! Do not attempt this project without expert assistance unless you are an adult experienced in working with extremely high voltage power sources. This project is intended only for very experienced adults. Severe injury, death, or property damage may result from failure to use adequate safety gear and precautions.

What’s more important: empowering readers to take control of technology, or protecting them from the risks? A spirited discussion between MAKE’s editors and technical advisory board ultimately led us to cancel publication of the high-voltage “Lifter” project in Volume 09.

The piece was written by John MacNeill, a well-known illustrator whose work appears frequently in publications such as Popular Science. MacNeill is also a “lifter” hobbyist who has made several of the mysterious levitating devices, and the how-to project he submitted was excellent. We were very excited to run it. However, MAKE’s technical advisory board, consisting of engineers, how-to book authors, and researchers, deemed the project to be unsafe, due to the project’s high voltage conducted across exposed wires in a flying object. Would strong warnings suffice, or did we need a full primer on high voltage? We also worried about recommending reuse of a TV tube (CRT) as a power supply, due to the dangers of capacitance discharge, and the unknown voltage and current. But even with a store-bought DC power supply, could the current of 0.4 milliamps be deadly? (Probably not.) Would the current-limiting knob protect makers? (Probably so.) Was the project too tempting for inexperienced teens? Isn’t it MAKE’s mission to empower people to handle technology? And, having established an email thread of world-class makers questioning safety, what about legal liability?

Magazine spread.
The article that almost was…

We made a tough call. Tell us what you think at in the talkbacks below.

Mark Frauenfelder, editor-in-chief: Dear MAKE technical advisory board members: Attached is the layout for one of the projects in MAKE Volume 09 — a high-voltage “lifter.” The instructions call for a high-voltage DC power supply, but offer the alternative of using an old (pre-Energy Star) CRT monitor to supply the power:

Using an Old CRT as a Power Supply

Here’s how to adapt an old (pre-Energy Star) CRT monitor into a high-voltage power supply that’s adequate for a small lifter. Unplug the monitor and let it sit for at least an hour to allow residual charge to dissipate. Open up the monitor, and locate the large wire that leads to a rubber cup at the back of the tube. This wire supplies the tube’s electron gun. Lift up the cup and find a metal contact for the wire.

Run one insulated wire to the electron gun contact and another insulated wire to the metal spring framework that holds the CRT. These will feed the lifter’s emitter and the ground, respectively. Position the 2 wires as far apart as possible, close up the case, and you’re ready to go.

I’m a little concerned about these instructions because I’ve heard CRTs can hold powerful charges almost indefinitely. I guess you could drain the charge by shorting the leads with a screwdriver, but that makes a scary spark and noise.

What I’d like to know is (a) whether my concern is valid, (b) if it is, is there a safe way to dissipate the charge? and (c) is there anything else important that’s left out from this? Thanks for your help!

Now read what members of the MAKE Advisory Board advised, and let us know what you think.

22 thoughts on “Unsafe at Any Amperage? Our Dilemma from Volume 09

  1. zof says:

    I believe you were right to error on the side of caution on this one, I’m sure there are quite a few high school students and others that read this magazine that don’t know nearly enough to protect them (including me, not the high school part). While I would not have put the instructions in the magazine I would have put 1 or 2 page overview of the project in it then with link to the project on your website where you could restrict access to subscribers 18 years of age and older along with an agreement with the customer that makezine can not be held liable for your carelessness.

    To me that would be a happy medium of rights vs safety, with that project in there I might think twice about handing that issue over to someone less than 18 years old.

    Either way good call on your part by holding it back.

  2. Anonymous says:

    Best way to discharge a cart is with a bleed resistor.

    Get a 5 to 10W 1K resistor and attach to cables to each end. cables must be high voltage rated.

    Attach alligator clips at the ends of each cable.

    Put heap of heat shrink over the resistor in the middle.

    to disharge attach a lead to a good earth.

    The other alligator goes to a long handled screw driver (flat blade)

    The flat blade slides under the rubber plug in the crt to the metal pin.

    Use some good insulative gloves when you do it.

    Hold the resistor in place for a good 30 seconds or more to be on the safe side.

  3. Polynonymous says:

    What’s already been posted – even just a single paragraph summary with a picture – is enough for some reckless kid to attempt this and hurt themselves.

    If you post full details WITH adequate and reasoned safety warnings and instructions, then the same kid will read the more detailed instructions, and while he may not do it entirely right and safely, will probably at least do it safer than he would otherwise.

    I understand that by posting full details you may be held liable and you must avoid that, but that is a shame since it will kill people to take the legal safe road.

  4. Duh says:

    I have met the people who pioneered this research, and even they had one too many close calls (serious burns).

    This device could seriously endanger someone, and the arrogant kid that will try this is likely be the first to learn the lesson.

  5. anon says:

    while it is good to be cautious about high voltage, I’m surprised nobody has commented on the fact that this is in no way anti-gravity, it actually just forms a small air current to lift itself.

  6. Friedrich Nietzsche says:

    What doesn’t kill us makes us stronger.

  7. James B. says:

    The risk of shock is a reasonable concern in this instance because of the way the device is implemented. Yes a careless experimenter could get zapped. I think extra safety precautions could be implemented by the builder. That is their choice and responsibility.

    Also, it is important to note that young people are not as dump or careless as we may think……ok maybe, but we should be involved as parents when they want to experiment in this fashion. As a teenager, I could go to my father or someone with authority an ask them for ideas or assistance with a project or experiment like this. Sometimes I’d get .. “you’ll shoot your eye out kid!”…but most of the time, they would volunteer there time to show me the safe and correct way to do something.

    I would like to see make magazine publish a SAFER implementation of this project. Maybe a less adhoc setup would encourage people to do it the right way.

  8. austin y. says:

    I always loving coming across lifters on the internet. My grandfather actually worked for Transdimensional Technologies when they began playing with the lifters. I was only about fourteen at the time, but i was able to spend a lot of time during one summer helping him build and test them. That was a pretty cool experience.

  9. says:

    Keep your perspective: is a hv CRT supply more dangerous than lighting candles in your dorm room? Driving a car? Or (gasp) USING A TABLE SAW? Not by a long shot. Mistakes with crt supplies give you a blister, not some missing fingers or a charred or mangled torso.

    Note that current-limited, under-1-mA HVDC power supplies are PROBABLY less dangerous than 120VAC. Gentle contact causes arcing and skin burns. Firm contact creates a current too small to feel, so there’s no muscle contraction or “clamping on” of your hands to conductors. Not so with 120VAC.

    The real danger of CRT supplies is the initial “zap” from energy stored in any parallel capacitance. Larger energies tend to defibrillate. Not so with 120VAC.

    In the hobbyist Tesla Coil world there’s an interesting effect contributing to safety: people tend to be terrified of high voltage. Encourage this by adding some big red banners to the article: ELECTROCUTION HAZARD, THIRTY THOUSAND VOLTS. Get some yellow “high voltage” warning tape from Archie McPhee and feature it in photos strung up surrounding the device. So, if anyone dares to build the project at all, their fear will make them go overboard on precautions. If others are like myself, then it’s usually the most experienced hobbyists who eventually drop their guard and get into trouble! :)

    At the same time, “common everyday” 120VAC just doesn’t have the same psychology, so with its clamp-on muscle effect and enormous maximum current, it can add up to being way more dangerous than DC high voltage.

  10. Adam says:

    Come on, you should know this. There is no such thing as “Amperage”

    Call it current, then we’ll all be happy :-)

  11. Milan Karakas says:

    I’m experimenting with high voltage since my childhood. And, I was zapped countless times with low and high current. It hurt either way, more or less. But that is not only one problem here.

    Nobody mentioned what to do in case of fire. And, even worst, when fire is combined with presence of dangerous power line voltage (110 or 220 volts), toxic fume rush out from electrolytic capacitors, or other flammable or non-flammable elements inside power supply, or from other places. I had such situation from time to time in my life. Fortunately, everything was fine at the end, but it may be catastrophic.

    My recommendation is that before doing experimenting with high voltage, we should think about all possible dangers, not only about how high voltage or current may be, or how badly one may be zapped with HV.

    How many of you, high voltage experimenters, have fire extinguisher with proper class at experimenting site? Me neither.

    Anyone have gas mask? Me neither.

    Do you have anyone near you in case of accident, so that they can call emergency, or help you extinguish fire or help you abandon site of accident? Me neither, I’m always alone when experimenting with potentially dangerous things.

    Anyone moving away flammable things from experimenting site, such as: carpet, wooden things, curtain, papers, and other potentially flammable things? Me neither.

    I consider myself lucky, winning a ‘lottery of life’ after each accident. Do we need playing a ‘Russian roulette’ each time experimenting?

    Well, everyday life is full of danger. Anyone may have different answers to those questions. Nobody play on safe, nor can play on 100% safe. Such is life. Be careful as much as possible.

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I'm a word nerd who loves to geek out on how emerging technology affects the lexicon. I was an editor on the first 40 volumes of MAKE, and I love shining light on the incredible makers in our community. In particular, covering art is my passion — after all, art is the first thing most of us ever made. When not fawning over perfect word choices, I can be found on the nearest mountain, looking for untouched powder fields and ideal alpine lakes.

Contact me at or via @snowgoli.

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