From the archive, originally posted by: [ spectre ]

Unsafe At Any Amperage?

by Tom Anderson, Gareth Branwyn, Shawn Connally, Dale Dougherty, Mark
Frauenfelder, Joe Grand, Saul Griffith, William Gurstelle, Bunnie
Huang, Tom Igoe, Mister Jalopy, Steve Lodefink, David Pescovitz,
Charles Platt, Paul Spinrad, Phillip Torrone, John MacNeill
March 16, 2007

Behind the scenes of our high-voltage dilemma: whether to publish a
dangerously cool project in MAKE magazine’s “Fringe” issue.

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

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

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
Too Much Juice from a CRT?

Charles Platt, technical advisory board: This is like asking me if it
is a good idea for Wile E. Coyote, in a Road Runner cartoon, to mix
gunpowder with birdseed – so long as he is veeery, veeery careful. My
response: We cannot count on him to be quite careful enough.

I would not publish the CRT idea.

Reason 1: There is no guarantee that the capacitor inside a TV will
discharge itself within an hour. Depends on the TV, depends on the
circuit inside. Also, even if it is true, it depends on some young
reader being willing to wait an hour. “Hey, look, it’s 15 minutes
already, that should be long enough.”

Reason 2: Subsequently switching on the TV, after attaching wires to
the high-voltage end, is a risk that I personally would not take.
While I do not have the numbers, I strongly suspect that the high
voltage inside the TV is backed with considerably more current-
delivering capability than you need or want for a lifter. In other
words, a TV is not like a Tesla coil which can harmlessly envelop you
in very high voltage at negligible current. Everything I have read on
this subject encourages me to think that a TV can kill you.

Reason 3: You are going to damage your credibility by suggesting this
approach, because so many warnings against doing it have already been
published elsewhere. It will be MAKE vs. the rest of the world, which
is not a good position to put yourselves in unless you are absolutely
sure of your facts (which apparently is not the case), ready to fight
lawsuits, and eager for publicity.

I have no patience with the “Nanny State” and other entities that try
to protect us from ourselves. Personally I have made explosives, have
subjected myself to 240VAC numerous times, and have tried hang gliding
and other risky activities. But for whatever reason, superstitious or
otherwise, I would not poke around inside an old TV set.

Steve Lodefink, technical advisory board: From what I understand, the
dangerous part of a CRT (the part that can kill you) is the shadow
mask connector. This is connected to the side of the tube, also by a
black suction “cup” looking thing. So, I can see a potential for
someone mistaking that for the gun connector.

I hear that it is the shadow mask that causes the tube itself to
become a huge capacitor. That is the part that can hold a charge for a
long time, so we would want to warn against messing with that.

Tom Igoe, technical advisory board: My friend built a lifter a few
years ago and wrote about it. He said he tried to use his CRT, and
found that the current-limiting circuit stopped him because he
couldn’t generate enough to get it off the ground before the CRT shut
off the current. It was probably a post-Energy Star one. He ended up
using a DC power supply he bought online, but he said the guys he
interviewed swore by the CRT method, as long as you avoided the
capacitance problem.

In any event, your hunch on capacitance discharge is right, I’ve
chomped the ends off a few screwdrivers that way before, but never had
to try it on a CRT. I’m a chicken, though, and not only used insulated
drivers, but also wrapped the handle in a thick piece of rubber and
wore rubber gloves. I’d never do it if I knew the possible amperage
was over about 500mA, though, because theoretically a full amp will
kill, and I have no desire to find out.

Shawn Connally, managing editor: We were, in fact, discussing the 1
amp (deadly) vs. 0.4 milliamp needed to fly the lifter (lots and lots
less amperage), and were wondering if there was something else we
could use. I guess the problem is the high voltage necessary. I will
go warn the interns [Matthew Dalton and Jake McKenzie]. Now that I
think of it, it has been very quiet in that room the last hour or so.
Hopefully they haven’t fried themselves up!

Charles Platt: Interesting that your interns did the TV thing. I just
went looking online and found that, allegedly, the tube carries up to
35,000 volts at only a couple of milliamperes. This is somewhat
reassuring. On the other hand, further reading indicates that very
high voltages may be dangerous because at high frequencies, the
nervous system does not detect the electric input as pain, even though
the current prefers flowing through the soft tissues and circulatory
system rather than the skin, which has a higher resistance. So you may
damage yourself without even knowing it … allegedly. (See the
Wikipedia entry on Tesla.)

Add it all up, and who can say? May be safe, may not be safe.

Mister Jalopy, technical advisory board: The whole thing gives me an
upset stomach. I won’t work on CRTs as I understand the charge lasts
for weeks, not an hour. Wikipedia CRT entry backs that up. The other
fellas know more than I do about this, but I wouldn’t attempt this
project based on these instructions for anything.

I would pinpoint a power supply by specification (kV, A) and not give
alternates. Otherwise people will be killing themselves with neon
transformers. Let people Google if they want a cheaper (more
dangerous) solution.

Charles Platt: High voltage just requires a suitable transformer. How
about eBay? Search for “Tesla transformer” and you’ll find a bunch.

Frankly all of this stuff makes me nervous, even to the extent that I
would not want to be the writer advising people on using it. I could
easily see myself being named in the suit for negligence. And I don’t
scare that easily.

My father, the chief engineer at a British automotive company, told me
that at their testing lab, they had to use very high voltages. The
employees had to stand on rubber mats, wear rubber gloves, and
literally work with one hand tied behind their backs (to avoid the
risk of a hand-to-hand heart-stopping jolt). If your readers had this
much discipline, it would be no problem. But, I don’t think they do.

A childhood friend gave himself a 600V shock while wearing a pair of
bedroom slippers. When he picked himself up off the floor, he found
the slippers still where he had been standing in them, facing the
workbench. He had literally jumped straight out of them!

I’ve seen too many near-fatal episodes. I have also seen, in an animal
lab, how easy it is to stop an animal’s heart with nothing more than
110V AC straight out of a wall socket.

Big Blinky Flashing Skulls and Suicidal Tendencies

Joe Grand, technical advisory board: Yikes. In theory it sounds fine,
but is very dangerous any way you look at it. You would definitely
need to discharge the monitor with a screwdriver and not just let it
sit for an hour. The CRT could also gather charge again over time (I
think). I’m concerned that this article is oversimplifying the process
and could seriously injure a large portion of our readers who aren’t
properly trained in handling electronics like this. Even I am still
overly cautious when working with monitors and usually discard them
instead of trying to fix them. Just too risky. Maybe some of the other
guys have suggestions to make this method safer, but to me it just
sounds too risky to promote in a now mainstream magazine like MAKE
(especially without some serious disclaimers, which still might not
help to protect you or our readers). To me, high voltage and high
current are extremely serious and should be treated with the utmost
respect – that is, actually paying money for safe power supplies that
have no (well, less, if used properly) risk of killing you.

David Pescovitz, editor at large: So if a good power supply solves the
problem, why not just remove the CRT section entirely? When we mention
that you need the power supply we could also tease that we’ll have
other projects in future issues that require one. (Desktop Tesla

We could also mention that some people use a CRT as the power supply,
directions to do so can be found online in various places, but that we
think the risk outweighs the benefit and cost savings.

Phillip Torrone, senior editor: OK gang, here’s my opinion – this
[CRT] sidebar without any doubt could kill someone in the procurement
and in the operation if you screw up. We do a good job suggesting the
DC power supply, let’s stick with that.

So – I’d kill the CRT portion of the print article, and on the [web]
article page, link to the many articles online that show how to use
and discharge CRTs. Online, we could always pull stuff if someone was
stupid after seeking more info, and add big blinky flashing skulls
that assure death if they’re not careful.

CRT Option Killed, Warnings Added

Shawn Connally: We have decided to take all the references to using a
CRT out of the piece. We’ve also added a much sterner warning,
actually two – one on the Materials page and one as a sidebar,
“WARNING: When You Work with High Voltage.”

I’m really torn about this project after reading replies all day. I
saw the interns working on this project for a couple of weeks and
never thought a bit about it. They, of course, measure current at
every step, but they never seemed too worried about it. They were
actually more frustrated in how hard it was to get the lifter to
float, than worried about working with high voltage. Ah, youth.

The author also doesn’t seem too worried about it, but was willing to
rewrite bits and add the warnings. I’ll discuss more with Mark; should
we not be running the piece at all? Should we put a big Editor’s Note
at the beginning? It’s a tough call, especially late in the production

Unsafe at Any Amperage?

Tom Anderson, technical advisory board: Uncontrolled flight of metal
objects at 20kV and unknown current. Hmm…

There is more than one way to die from high voltage. Electrocution is
not the only problem. Getting hit with a high voltage causes a strong
convulsion that “throws you across the room.”

It turns out that the power of our muscles is controlled by our
nerves. Our muscles have more than enough strength to break our bones,
but our nerves talk them out of it. The high-voltage hit will override
your nervous system. Suddenly you can fly! (For a short distance, and
landing is a bitch.)

The disposable camera flash in the flash kit [see MAKE Volume 04] also
has high voltage, and the spark made a good picture. I have been hit
by it multiple times (mostly because I was being stupid and didn’t
short the capacitor). While it hurt like hell, I haven’t ever felt in
danger for my life. On the other hand, the lifter project says
“suicidal tendencies” to me, and at least calls for a level of
sobriety that is, well, sobering.

I am also chicken about such things. Some years ago I worked with
lethal voltages for about a year at work, and have the training for
how to deal with it. I’m not seeing enough safety information in this

In the disposable camera hack, I took the direct hit multiple times
and decided that it wasn’t too bad, and went on with the project. I
wouldn’t recommend that anyone take the lifter hit to “see how it
feels” with this project, because you might not live through it.

I can make a few recommendations to improve the safety of the design
and to help people protect themselves from it, but I am hesitant to
have anything to do with it, other than to say “No!” I don’t want to
advocate cruelty or anything, but if you’re not willing to take the
hit yourself, and you aren’t willing to test it on an animal, do you
really want to test it on your readers?

The project (at least!) needs a ballast resistor to limit the current
to decrease the electrocution risk. Also it needs a primer in high
voltage safety. I’m really concerned about the safety of this one.
Perhaps a better title would be “Unsafe At Any Altitude.”

Saul Griffith, technical advisory board: I’m with Tom, or perhaps I’m
more conservative than Tom. I don’t think you should go anywhere near
this one. There is no description of how much insulation you really
should have on those wires, dielectric constant of air, and how you
may not even have to touch the wires to get f***ed up.

This stuff is dangerous – Eric Wilhelm and I did a lot of 20kV
electrostatic work at MIT and you could not possibly be careful enough
with that stuff, we had the full rubber gloves and shoes and paranoia
and still shook uncontrollably as we smelt the ozone and felt the
charge in the air. I had a small shock myself that made me extremely
wary of this stuff, probably a 5kV discharge.

The guys who designed these projects probably know enough to be really
scared, and have worked with high voltage enough to be competent when
scared. I just don’t think it’s worth the risk to instruct the general
public. It’s not worth making a free speech issue out of a high-
voltage project.

My technical advisor vote would be not to run the article, and I’m not
exactly scared of dangerous things. I think it’s like running a “how
to swallow a sword” article. Sure it can be done safely, but only if
you’ve had a lifetime of training.

Shawn Connally: All the emails sent by the tech advisors have had a
sobering effect on my thoughts. I am still inclined to leave the
project in, and [art director] Daniel Carter and I have added 2
warnings, but I’m happy to have us scramble and replace it if that’s
the decision we go with.

You might discuss with the interns as well; they say the monitor they
used couldn’t hold a charge of more than 1.7 milliamps, I think it
was. Basically, enough to give a nasty sting, but not kill.
Do Not Try This at Home, Kids

Dale Dougherty, publisher: Is there a way to change this from a
project into an article that shows how the author did this but doesn’t
characterize it as a DIY project? In other words, we can talk about
how it’s done, and how strange it is, and even discuss the procedure
for building it, without actually walking through the steps to do it
as we do in a typical project.

We could even put some of this discussion of high voltage into the
article and be up front that we planned to present it as something you
could do yourself but despite it being cool, we don’t recommend that
you do so.

Gareth Branwyn, technical advisory board: I can speak to the
temptations of wanting to build such a project and not having years of
experience. Reading over this piece, I think: “Cool. I want to build
this!” Now, I’m an extraordinarily cautious person when it comes to
being out of my depth technically, and especially around rogue
electrons. So I might be okay attempting a project like this.

But I think of my teenage son who reads stuff in MAKE all the time and
says: “I wanna build this!” (which goes right alongside other instant
gratifications like: “I wanna get a PS3!” and “I wanna get an
iPhone!”) This project is the kinda thing that would totally make him
wanna. He would read all the cautions and try to take them to heart,
but have no real sense of the dangers involved (he’s a teen; he’s
invincible). I can imagine lots of teens wanting to try this project
out and in some ways actually being “inspired” by the warnings in the
It’s Not the Voltage, It’s the Power – Volts Jolt, But Mils Kill

Paul Spinrad, projects editor: Our Kirlian photography project [MAKE
Volume 09] also uses a high-voltage power supply, although it’s more
contained, rather than having wires strung around. Danger mainly comes
from the power, not just voltage – a doorknob spark is high-voltage.
Here are the powers used in Lifter and Kirlian, compared to a stun
gun, from an online description from a manufacturer:

Lifter: 20-25kV DC at 0.4 mA (DC) = 8-10 watts
Kirlian: 5kV at 1-5 mA (AC or DC) = 5-25 watts
Stun gun: 20-150kV at 3 mA = 60-450 watts (source:

Although it’s also true that with the lifter, the voltage is way more
out in the open.

It could also be true (I don’t know) that a human body has less
resistance than the lifter, and would draw more current – but if you
keep the amperage limit knob on the supply set to 0.5 milliamps, as
the sidebar suggests, then the supply is supposed to shut off if
anything draws more. Not that I’d want to test it myself…

Mark Frauenfelder: Well, I still think if we add dire warnings to
this, we can keep it as a project. You are right, though, it’s all
about the power. I’ve been shocked by an old spark coil (from an
antique Ford Model T) which is high-voltage. It’s not fun, but it’s
pretty harmless. has been publishing lifter
plans for years, and they have a nice safety guide. I think we should
feel OK about running this if we include a warning like the one in
their PDF:

Warning Notice: This document is intended for educational use
only! The project described in this document uses extremely high-
voltage power sources, and is intended for readers over 21 years of
age who are experienced working with dangerously high-voltages. If you
are not a legal adult, or are not proficient working with dangerously
high-voltages, do not try to build this project without expert
supervision. The author of this document is not responsible for any
death, injury, or property damage resulting from or relating to the
procedures shown or devices described in this document.

If we run this in red text right before the instructions, I think
that’s a fair warning.

John MacNeill, author of Lifter article: As I understand it, the CRT
has already been dropped from the article. But to answer your
question, yes I have been shocked, and more than once. I’m not dead,
but I cannot warrant that a similar shock wouldn’t put your heart into
fibrillation (or interfere with a pacemaker).

Do you want to kill the article? There’s no doubt at all that misuse
of high voltage can be lethal.

Mark Frauenfelder: Isn’t it the case that a high amount of power is
what we should be concerned about, and not just high voltage?

Saul Griffith: At electrician school they teach you: “the volts just
jolts, it’s the amps that clamps.” But electrocution and fires are
stochastic. I’d still stand by care on this project.

Joe Grand, technical advisory board: Or “volts jolt, but mils
kill” (mils as in milliamps). Even still, a high voltage at small
current (possibly like the lifter) can still be extremely dangerous,
especially to the untrained. It’s just not worth taking on that risk.
Shocks, Burns, and the Rough Landing

Tom Anderson: There is no standard output current for high voltage
supplies, and nothing in the article tells you that more output
current or power capability is more dangerous. Indeed, the article
suggests that the design might be scaled up to build a vehicle! How is
the maker supposed to know how to select or build a high voltage

There are several safety problems: Current, voltage, and energy.

One of the worst shocks I ever experienced was from only 19V at
150kHz. I felt the aftereffects for days. I wasn’t being careful with
it because I didn’t believe I would even be able to feel it, except
with my tongue. [Editor’s note: Your tongue?]

It also depends on the capacitance of your load. The high-voltage
supply may not kill you, but high-voltage supply with a load capacitor
may kill you.

The other problem with voltage is “getting thrown across the room.”
Plenty of opportunity there to land poorly. In my garage you would
likely land on something that would hurt you. You can get thrown 10
feet (you actually throw yourself). Much of death by electricity is
caused by landing, not the voltage itself.

What is the output capacitance on the high-voltage supply? If it holds
more than a few joules it could cause severe burns. At 20 or more
joules it could cause fibrillation. A defibrillator typically uses 120
to 200 joules. They design the electrodes (paddles) to mimimize burns.

E = 1/2*C*V2. You have a large voltage term (V) and it is squared. If
you don’t know the capacitance (C), you don’t know what you are doing
or how dangerous it is.

The fibrillation electrocution risk comes from current. 60Hz AC is
worse than DC. Ground fault interrupters, which are designed to
prevent electrocution, trip at 5mA.

The other electrocution risk is from power causing burns. This can
happen at low voltage and high current, but is more common at high
voltage. Three joules will give you a small burn that you will be able
to feel the next day. You would get that from a 9W supply in a third
of a second. If you manage to grab the high voltage and “stick” to it,
you’ll be getting 9 joules per second until you get unstuck. (Watts
are just joules per second.) Maybe not fatal, but it would probably
change your attitude about electricity.

You have probably experienced a severe static electric shock of about
25kV. The capacitance of the human body is typically about 150pF, so
1/2*C*V2 comes out to 0.047 joules. A 300kV static electric shock
(from, say, a Van de Graaff generator mishap) will get you about 7

Unlike whirling blades and hot coffee, most people don’t have an
intuitive grasp of the danger of using high voltages or high currents.
Nor do they have voltage, current, power, or joule meters that work in
this range. I wouldn’t advocate working with a table saw while
blindfolded. People who work with high voltage generally have some
basic safety equipment, such as a way to measure high voltages safely,
and a better way to discharge a capacitor than arc-welding a
screwdriver across the terminals.

If there is interest, I will build a DC high-voltage power supply from
a neon sign transformer and let you see it firsthand. Unlike in a neon
sign, my DC supply would have an output capacitor that can store quite
a few joules. I’ll turn it on at your place, though, OK?
Needed: A Safe Working Primer

Mister Jalopy: I think there is a common thread amongst most of the
advisory board members:

* we have received some training on safe practices – even if it
was anecdotal and casual
* we (or people we know) have gotten a nasty shock despite being
* we know this thing is scary – which would not necessarily stop
us from doing it, but we would be damned careful

The problem is MAKE has never quantified what “damned careful” is. The
article says follow high voltage precautions, but they are not

I would like to see a Safe Working Primer that would be an article and
one-page cheat sheet that could be hung above your workbench. Maybe
the cheat sheet could even run in every issue. Or a laminated or card-
stock copy with a subscription. A free PDF permalink to the whole
article would be a great benefit to makers for years to come.

I don’t know what constitutes dangerous voltage/amperage, so I just
assume neon transformers, CRTs, and high-voltage car ignition systems
are killers. Similarly, I am not qualified to say how dangerous this
project is, but it sure looks scary with the high voltages and lack of
insulation, not to mention the added dimension of the thing flying
around. Without a detailed safe working section, it does not seem
prudent to run.
Passivity vs. Empowerment – McDonald’s or MAKE?

Charles Platt: A lot of the speculation here can be clarified by
checking standard reference sources. Wikipedia has a very good entry
on electric shock, dealing with issues of amperage, voltage,
frequency, and so on:

However, I think we’re missing the point by debating the specifics of
electrical safety. This is just one instance of a much bigger, general
dilemma that I would characterize as “Passivity vs. Empowerment.”

On one hand, we live in a world where McDonald’s got sued,
successfully, for serving coffee that scalded the thighs of a customer
who spilled it. From this perspective, the only legally safe policy is
to advise readers to be as passive as possible. They should never
enter a workshop or pick up a power tool, let alone start poking
around in consumer electronics products for fun.

On the other hand, as I understand it, the idealistically driven
mission of MAKE (which I believe in very strongly) is to encourage
readers to take control of technology, instead of being controlled by
it. The magazine’s mandate is to advise readers to be as active as

How do you reconcile this conflict? The dilemma is especially
difficult since MAKE has positioned itself as a reassuring, upbeat
publication that is friendly to the reader. To what extent does this
friendly relationship entail protecting readers from themselves? If
friends don’t let friends drive drunk, should friends encourage
friends to play with electricity?

These are questions that only my editors can answer!

Liability and the Nanny State

Bunnie Huang, technical advisory board: On the subject of passivity
versus empowerment – I’m not a lawyer but I’ve been in a couple of
legal scuffles now. I’d say that if someone was hurt executing the
article, this thread itself is pretty damning evidence against MAKE
for running the article. A panel of expert witnesses have essentially
testified just now about their scars from playing with high voltages,
and other stories they have heard about how dangerous and potentially
lethal something like this could be.

I’m a fan of empowerment, but I think to be fair you’d almost want to
publish this thread along with the article, and let the reader know
that a panel of the world’s best makers would exercise extreme caution
(or not even do such a project) because of the risks involved.

In an ideal world, dangerous ideas are not self-censored – and that’s
a core value of MAKE, I think. But I think there is an obligation to
tell the whole story, which would include not only the dangerous idea
itself, but the risks of the ideas and also what the experts think
about those risks. This ultimately places the faith in the reader to
decide appropriately on whether the idea is too dangerous for them. I
think people should learn good safety techniques for high-voltage
supplies, and a working knowledge of high-voltage supplies is very
empowering, but very dangerous … just like many other technologies
(munitions, cryptography … hah hah).

Probably the only caveat against this is if your demographic includes
a readership that could be considered minors. If MAKE has a
significant subscriber base of minors who are, at least in legal
theory, unable to decide good from bad even when presented with the
full monty, you may want to rethink things … I don’t know what the
standards are surrounding the protection of non-adults, but I get the
sense that the legal system has very little tolerance in that area.

William Gurstelle, technical advisory board: This is a question –
about publishing information that could hurt, injure, or kill if
misunderstood – that I’ve spent a long time considering.

Several years ago I published a book called Backyard Ballistics which
explained, among other things, how to build a device that shoots
projectiles at high velocities. Am I worried that someone might goof
up and get hurt? Of course. Is that a reason not to publish
information – that someone, anyone could make a mistake?

True story: a couple of years ago, a young adult in Texas built a spud
gun and went out in the swamp. He spent all day collecting bullfrogs,
tossing them down the barrel of his spud gun and shooting them into
froggy goo on the other side of the swamp. But on the last occasion,
his gun misfired. Against every warning and caveat possible, he looked
down the barrel of the gun, and as you probably guessed, took a fair-
sized bullfrog between the eyes with unfortunate results. (Google it
for details.)

Point is, just because someone could make a mistake with the
information you’re providing, it doesn’t mean the magazine is liable,
morally or legally. Unless it’s incorrect.

But if the info is correct, that is, it has been thoroughly vetted,
can be clearly explained, and contains plenty of warnings of the
magnitude of the consequences of error, well then, I say go for it. I
don’t know the first thing about high-voltage power supplies, so I
can’t tell how complete the MAKE explanation is, but if complete and
thorough information can be provided, then go for it. Nanny State be

Legal disclaimer: But as Dennis Miller says, that’s just my opinion; I
could be wrong.

Mark Frauenfelder: This is all such interesting information and advice
that I’m tempted to publish it in MAKE as a round-table discussion.

Thanks so much for offering your advice, Tom, and everyone else. We’ve
decided not to run the lifter project (at least not in this issue).


Did we make the right call? What do you think?

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Showing messages 1 through 9 of 9.

* Where would we be?

Where would we be, if in the past we had spent more time
worrying about the temperature of coffee and bullfrog-firing spudguns?

Would we have x-rays? Nylon? Space-flight, or even flight?

Now I am not suggesting that we should or can ignore these
warnings from others.

What I am suggesting is that forward-looking magazines like Make
tackle this issue head-on and find a way to publish articles such as
this, with appropriate warnings and disclaimers to protect both the
reader and the magazine.

I think this is a much larger issue than the technical details
of this specific quashed article.

Thank you for raising it for discussion by your readership. I
believe it reflects an ethos that could help pave a way out of this
type of mess.


Posted by BigNut on March 17, 2007 at 10:02:27 Pacific Time

* ion-driven lifter

this device was constructed and demonstrated on MythBusters.

Posted by GregKr on March 16, 2007 at 21:01:38 Pacific Time

* Hazard issues similar to tesla coils…

The amateur chemistry and Tesla Coiler communities have been
dealing with lethally dangerous projects for decades. For this kind of
advanced-level hobby project, the “barriers to entry” against young
children and total newbies take the form of 1. expensive and/or hard-
to-obtain parts and chemicals, 2. difficult instructions (it’s an
advanced project, after all,) as well as 3. repeated serious warnings
about the danger.

Only thing is… these projects aren’t inherently difficult.

To prevent problems, responsible authors will not only make very
clear that the dangerous projects are for advanced hobbyists only, but
also they’ll avoid removing the number one barrier. For example, they
won’t give formulas for simple explosives using common art supplies,
or Tesla Coil plans using easily modified television sets or microwave

I doubt that the Lifter article would attract a lawsuit as long
as sufficient warnings were given, and as long as the article *lacked*
simple detailed instructions easily followed by anyone. If they have
to ask questions, then they don’t have the skills needed. (And if they
insist on getting hurt, well, any number of dangerous project plans
are instantly available on the internet.)

Posted by wbeaty on March 16, 2007 at 18:03:44 Pacific Time

* Glad to see this kind of discussion

As someone who has written about Wi-Fi for years, in which high-
gain antennas seem to be used as toys by some hobbyists and even
professionals, I’m so pleased to see a discussion among experts –
people who know the risks involved. It’s great. (On the side of
telling people about safety, perhaps a Make piece called What Can Kill
You Or At Least Won’t Make You Stronger would be helpful, including
standing in front of multi-watt EIRP Wi-Fi dishes.)

I note that Charles Platt spreads an old trope, much like “Al
Gore invented the Internet”: “On one hand, we live in a world where
McDonald’s got sued, successfully, for serving coffee that scalded the
thighs of a customer who spilled it.”

McDonald’s was actually making coffee at a temperature far too
hot for human consumption. Numerous articles documented that
McDonald’s boost the heat far above (in one report, 20 degrees hotter)
than most of its competition.

I only bring this up because the McDonald’s lawsuit wasn’t
frivolous–it was part of a pattern of disregarding a serious problem
that the company was allegedly well aware of. This kind of groupthink
or negligence or whatever it was is clearly NOT being exhibited at

Posted by eggboard on March 16, 2007 at 14:50:06 Pacific Time

* Good call

Playing with flyback transformers and CRTs is best left to
professionals (or at least hobbyists with experience in high-voltage
power supplies and circuits). I’ve hooked up a simple circuit using a
high-voltage flyback transformer from a CRT (
p=34) and found that it can easily melt the anode and cathode leads.
There is no current regulation in the flyback transformer, but instead
it appears to be proportional to driving voltage and correlated with
the driving frequency. In my humble opinion, it was wise not to
publish the article from a liability standpoint, but none-the-less it
would be a very interesting read.

Posted by special4k4 on March 16, 2007 at 14:45:10 Pacific Time
o Good call (maybe not.)

Flipping through Volume 9 (I’m a loyal subscriber!), I
noticed the following in the materials section for the Kirlian Digital

“High-voltage power supply: You can use a Tesla coil,
induction coil circuit, high-voltage flyback transformer circuit, or
any other source that puts out 5,000+ volts, between 1-5 milliamps, at
any frequency (or DC).” (emphasis mine)

The article then goes on to suggest:

“Shooting people: Sooner or later you are going to want to
shoot people. The best place to start is the person’s
fingertip…” (again, emphasis mine)

I then must ask, where was the editorial review when this
article was published? It seems more dangerous (higher current power
supplies suggested, few warnings other than “make sure the subject
doesn’t touch ground”, and suggestions to directly connect the HV
power supply to bare skin). If anything, the levitator article seemed
like it would have recommended safer experimental procedures with the
current-limiting ballast resistor. Seems as though the above
discussion on the levitator never happened for the Kirlian Digital
Photography article.

Any explanation?

Posted by special4k4 on March 16, 2007 at 15:49:30 Pacific
+ Good call (maybe not.)

You can make the power source for Krilian
photography without taking apart a CRT, I suspect.

Plenty o’ folks have done 5kV at 20mA with no ill
effects. I’ve done it by accident myself. I suspect getting zapped by
the lifter wouldn’t be that bad. But if you take apart a CRT to build
a lifter power supply, you start dealing with capacitors.

The big problem is that the email thread is too
damaging a record, I suspect. It would be subopaenaed and come back to
bite them were a lawsuit to be filed.

Posted by wirehead_arts on March 16, 2007 at
16:06:36 Pacific Time
# Good call (maybe not.)

Naturally, we must always protect everyone
from themselves. What fool would think that technically-minded people
could make decisions for themselves and to determine their own limits?
Why not place everyone in stasis, ensuring our
safety for all time?

I could possibly agree with em on the
liability issue, but that’s not a problem with the technology or the
source so much as the overabundance of professional victims out there
with a lawyer on speed dial.

Posted by velojym on March 16, 2007 at
21:44:30 Pacific Time
* Good call (maybe not.)

The problem is that even though most
“technically-minded people could make decisions for themselves and to
determine their own limits”, the publishers could not assume that all
“technically-minded people” will make wise decisions. Given that all
of the technical advisors are “technically-minded people,” it was
clear that not all of them were aware of the dangers of HV power
supplies and did not know their limits and what precautions should be

I still believe that the project should
be constructed under the supervision/guidance of other individual(s)
with experience in HV electronics; however, in retrospect, I agree
that information wants to be free and that it is important to
disseminate it to encourage hobbyists to learn, experiment, and have

As I say on my site, safety is the
primary concern when working with high voltage circuits. Always be
careful, use extreme caution with high voltage circuits, and play it

My questions then is why they axed the
safer article (IMHO) and chose to publish the one that recommends
connecting a HV supply directly to an individual’s skin for long
exposure digital photos. I would like to know what the decision
process was to publish one while cutting the other.

Posted by special4k4 on March 17, 2007
at 10:14:31 Pacific Time