| Author |
Message |
Vidor Wolfe
Guest
|
 Posted:
Tue Feb 01, 2005 11:45 pm Post subject:
Re: TESLA COIL (0/1) |
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"Mark Fergerson" <nunya@biz.ness> wrote in message
news:3ZNLd.1514$Tt.1450@fed1read05...
| Quote: | Vidor Wolfe wrote:
"Mark Fergerson" <nunya@biz.ness> wrote in message
news:bOtLd.4534$6u.1006@fed1read02...
Snipped...
It's a school project. Explaining its failure modes is better than
having it work perfectly and not being able to explain why.
Mark L. Fergerson
|
Too true.
Then again, if he made both, he could show a reliable working coil and with
the bottles, show problems that Tesla himself had with his jar/bottle caps.
I'd imagine though, if his caps are too far out, it'll be out of tune and
not work.
This brings the new problem of racing sparks on the secondary or sec to
primary flashover. (Both symptoms of poor tune)
This could destroy a lot of hard work, ref 1500 turns of wire.
Just a thought.
Cheers.
Mark H.
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Bill Bowden
Guest
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| Posted:
Wed Feb 02, 2005 8:22 am Post subject:
Re: TESLA COIL (0/1) |
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| Quote: | If you have a plumbing question, I'm your guy.
Electronics...nada from me.
|
I have a plumbing question. I get this loud humming
noise from my water pipes when I shut off the water
after taking a shower. I can't find any leaks and if
I flush the toilet, the noise goes away and doesn't return
until next time I run the hot water for some time.
Any idea what is going on with the water pipes?
-Bill |
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Guest
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| Posted:
Wed Feb 02, 2005 5:09 pm Post subject:
Re: TESLA COIL (0/1) |
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HI to all.
Not to many posts have hit on the SAFETY aspect of what you are doing.
Just remember that those 15000V neon sign transformers are running at
50/60Hz
and can be lethal.The ones I have can supply up to 30mA at 15000v.Not
very pleasant if you get a shock :0(
Remember to take care....
Cheers
Rob
Blackbeard wrote:
| Quote: | Well you guys are talking electronics and
Alright. You guys are talking over my head. Electronics is definitely
NOT something I am familiar with. So I figured I could attach the
pictures of what my son has completed so far.
From what I gather, the only thing he has left to do is connect a
transformer and a spark gap.
When we tested his spark gap by connecting one wire to one of the
copper pieces and the other wire from the transformer to the other
side, the sparks to jumped across. However, he used hot glue to hold
the copper pipe in place and the heat melted the hot glue. So we've
gotta re-think that plan.
If you can take a look at the pictures, maybe it will give you a
better idea of where he is and what he's trying to accomplish.
Sorry for my ignorance on all this stuff. If you have a plumbing
question, I'm your guy. Electronics...nada from me.
One the pictures, the primary is made using 50-feet of 1/4OD
refrigerant tubing. The secondary is made by winding 24-gauge wire
approx. 1500 turns onto a piece of 4-inch pvc. The toroid is made
from
a piece of semi-rigid duct attached to a 5-gallon bucket top. The
5-gallon bucket top/toroid uses an upside-down toilet flange to
easily
attach to the extra pipe that runs through the center of his
secondary.
We are using a 15,000-volt neon transformer for power.
On Sun, 30 Jan 2005 09:23:56 -0700, Mark Fergerson <nunya@biz.ness
wrote:
Blackbeard wrote:
My kid is building a tesla coil for his science fair project. I'm
a
plumber, not an electronics guy. Right now, he has put together a
primary coil (made from 1/4" OD copper tubine) and he has a
secondary
coil made from (approx. 1500 winds of 24-gauge wire around a piece
of
4" PVC pipe). He made his toroid out of semi-rigid as the plans
suggest.
Now he's getting held up on the capacitors and spark gap. His
plans
call for 1-1/2 copper to make the spark gap. I can't see any point
in
using 1-1/2" copper (mostly because I have 3/4" immediately
available). Will it make any difference if we use 3/4" copper for
the
spark gap instead of 1-1/2" copper. The plans call for 7 pieces of
1-1/2 copper (2" in length). You put them in series and the spark
arcs
from one piece of copper to the next. Seems to me it would do the
exact same thing with 3/4" copper. But 3/4" copper has less copper
(thus (I assume) less resistance). Will that make a difference or
can
we go with the 3/4"?
The curvature of the pipe's surface partly determines when the
gaps
"fire" (what voltage they can get up to before they arc over). The
greater the curvature (smaller diameter), the smaller the voltage.
This
is ordinarily not an issue, but if your primary circuit isn't
running at
a high enough voltage it won't arc at all.
But mainly, the pipes are going to get hot just from carrying all
that current. The more thermal mass (more copper), the better.
Duplicating somebody else's plans allows you to duplicate their
results. Change something and you get different results, and you
might
not be able to tell what's going on (or what will happen); change
too
many things and you're almost guaranteed to let the magic smoke out
of
something with no clue what went wrong, leading to tossing the thing
aside in favor of video games (assuming you don't burn the house
down). ;>)
Also, the plans call for a home-made capacitor made by rolling a
piece
of aluminum flashing and piece of plastic or rubber. They say to
roll
it tight. But they give no directions on how to hook this thing
up. I
have TWO posts on the high voltage transformer (15,000 volts).
Oh, dear. Rolled caps are multiple disasters waiting to happen.
"Beer
bottle" caps are simpler and more tolerant of, um, errors in
execution.
How would one go about building a beer bottle cap?
Hooking the thing up should be fairly obvious; do the plans
you're
working from not include a wiring diagram?
I assume the sequence I need to follow is
1. Connect both posts from the transformer to the home-made
capacitor
(how?)
2. Run a wire from the capacitor to the spark gap (those pieces of
copper pipe..again, how?)
3. Run a wire from the spark gap to the primary coil
Where'd he find the plans you're using? I don't expect you to
draw a
diagram, but if you could refer us to a webpage...
4. How does the secondary coil get power? One person told us that
the
secondary coil should just be grounded and that the 1500 turns
would
generate a magnetic field and generate energy (ie, the lightening
that
hops of the toroid)
"One person" doesn't quite know what he's talking about; all the
energy comes out of the wall plug and is transferred (minus losses)
through the system from gap, to primary circuit, to secondary
circuit,
to ground.
Ordinary transformers consist of coils that transfer energy very
efficiently through their magnetic fields, and are designed to work
at
line frequency (60 Hertz here). Tesla coils aren't quite like
ordinary
transformers; they're coupled resonators and you can design them to
work
pretty much at your frequency of choice, typically a few thousand
Hertz.
Put way too simply, when the gap fires the primary tank circuit
(inductor and capacitor) "rings" at its L-C frequency like a struck
bell
except it generates an oscillating magnetic field instead of
radiating
sound, and the field induces oscillating current in the secondary
(it
"rings up"). The toroid forms one plate of a capacitor, and the
ground
the other (which is why you ground the bottom of the secondary; "one
person" got that right). The secondary current charges up the
toroid's
capacitance. When the voltage on the toroid exceeds the breakdown
value
for air, the "lightning hops off the toroid".
I said "way too simply" because there are subtleties like the
fact
that the secondary will not resonate at the exact same frequency as
the
primary. Being able to point out and explain those subtleties will
get
your son a better grade, and teach him a few things.
Also, the voltage gain in Tesla coils is _not_ directly
proportional
to the secondary/primary turns ratio of the coils like in ordinary
non-resonant transformers, but rather to the ratio of the primary
circuit/secondary circuit capacitances. The secondary needs lots of
turns to get enough inductance to resonate with the miniscule
capacitance of the toroid. You want lots of voltage gain, so you
want a
large primary cap, which means the primary coil needs few turns to
resonate at (nearly) the same frequency as the secondary.
If the toroid doesn't "break out" into feathery streamers or an
outright blazing arc, all the energy stored in the secondary
capacitance
sloshes back into the primary circuit (because the secondary current
generates its own magnetic field, inducing current back into the
primary), which can do Very Bad Things to the primary circuit
components, and maybe feed back into the house wiring (depending on
your
actual circuit). It's a good idea to deliberately put a "breakout
point"
on the toroid to prevent this. Just solder a thumbtack to the toroid
point-out, and don't allow anything you value (like your son) to get
between it and the ground.
Our plans are pretty vague. Any experienced advice would be very
helpful.
Go to:
http://www.pupman.com/
and look through the FAQs on the left. Definitely read the Safety
Sheet:
http://www.pupman.com/safety.htm
to keep the fun from overriding prudence. We can't learn from our
mistakes if we don't survive them.
If your son seems to be "bitten by the Tesla bug", he might want
to
subscribe to the pupman mailing list. Lots of advice available from
helpful, friendly coilers; some with experience, some with degrees,
and
many with both. If that would be too time-consuming for this
project,
check out the Tesla webring; many pre-tested circuits out there to
use
as guidelines.
Mark L. Fergerson |
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Blackbeard
Guest
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| Posted:
Wed Feb 02, 2005 9:03 pm Post subject:
Re: TESLA COIL (0/1) |
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Thanks for giving me a heads up. I have posted out pics at
alt.binaries.schematics.electronics as you suggested.
On Mon, 31 Jan 2005 10:21:17 -0700, Mark Fergerson <nunya@biz.ness>
wrote:
| Quote: | Blackbeard wrote:
Alright. You guys are talking over my head. Electronics is definitely
NOT something I am familiar with. So I figured I could attach the
pictures of what my son has completed so far.
Whoops! No binary attachments (pictures) allowed in this group.
Repost to alt.binaries.schematics.electronic and we'll take a look.
From what I gather, the only thing he has left to do is connect a
transformer and a spark gap.
OK, but we'd still like to take a gander to help make sure the thing
works, and he survives.
When we tested his spark gap by connecting one wire to one of the
copper pieces and the other wire from the transformer to the other
side, the sparks to jumped across. However, he used hot glue to hold
the copper pipe in place and the heat melted the hot glue. So we've
gotta re-think that plan.
Epoxy works too.
You could get mechanical about it. Take a look at the top couple of
pictures at this link:
http://users.tm.net/lapointe/SparkGap.htm
for ideas how to mount your pipe sections. Notice particularly that
sharp edges on the little brackets, bolt heads, and like that are kept
far apart (and the pipe is deburred) so that the sparks will "want" to
jump only between the pipes themselves. Oh, yeah; the gaps between the
sections ought to be a millimeter or so.
You won't have to get quite so ornate; I picked this page pretty much
at random from a Google search for "copper pipe" +"spark gap" to show
some typical general construction methods.
Here's another that uses a fan to blow out the arcs to prevent what's
called "power arcing" and provide some cooling:
http://users2.ev1.net/~nmyreality/tesla/sparkgap/rqgap.html
Power arcing is when the gaps are still firing after the cap has
discharged into the primary coil and the transformer is basically
shorted across the gap, wasting its power instead of feeding more into
the secondary. Getting the gaps to stop firing when the cap has
discharged is called "quenching" them. The idea is to feed energy into
the secondary in lumps (every time the line voltage peaks, 120 times a
second), not to try to do so continuously regardless of the fact that it
LOOKS like it's continuous. Power arcing just overheats the transformer,
but if your son's coil isn't drawing lots of power, and/or he doesn't
run it for more than a few minutes at a time, this may not be worth
worrying about.
If you can take a look at the pictures, maybe it will give you a
better idea of where he is and what he's trying to accomplish.
Sorry for my ignorance on all this stuff. If you have a plumbing
question, I'm your guy. Electronics...nada from me.
Ignorance is not knowing how far what you already know can be applied.
You know about water hammer, right? That's the exact same kind of
resonance principle that your son's coil will use, except with
electricity. When water hammer gets extreme pipes break. When his Tesla
coil works right, the toroid similarly breaks out in sparks.
One the pictures, the primary is made using 50-feet of 1/4OD
refrigerant tubing. The secondary is made by winding 24-gauge wire
approx. 1500 turns onto a piece of 4-inch pvc. The toroid is made from
a piece of semi-rigid duct attached to a 5-gallon bucket top. The
5-gallon bucket top/toroid uses an upside-down toilet flange to easily
attach to the extra pipe that runs through the center of his
secondary.
That primary seems to have way too many turns. <mumble> gotta see
that diagram...
I say that because like most electrical gear, a TC ought to be
designed and built from the business end backwards. You have your toroid
and secondary, which pretty much determines the frequency they'll run
at. You have a primary coil and its dimensions fix its inductance range,
so what's left is to figure out the capacitance the beer bottle cap will
need (how many bottles, how big a bucket) so the primary circuit can
resonate with the secondary circuit.
Then there's tuning the primary; this is analogous to adjusting the
lengths of the parts of a plumbing system to get the loudest water
hammer, but since the "customer" end is fixed you have to adjust the
"supply" end.
When everything's built and powered up, don't be surprised if he
doesn't get lightning right off the bat. It's really difficult to adjust
a beer bottle cap in small steps, so it's simpler to move the primary
connection ("tap") along the copper tubing to find the "sweet spot"
where the primary coil is in resonance with the secondary. This involves
connecting the wire to the copper tubing with something he can loosen,
slide along the tubing say an eighth of a turn at a time, then retighten
(the part of the tubing "hanging loose" doesn't affect the primary's
inductance). Some folks prefer modified fuse holders, other use a short
piece of copper pipe strap. Whichever, only move it when the system is
UNPLUGGED and he's shorted the primary capacitor to remove its charge.
The charge stored on it can KILL!
Your son will have to learn a little math and get familiar with some
equations to guess how much of his primary will resonate (where to put
the tap to get started) with the cap you end up using.
We are using a 15,000-volt neon transformer for power.
Is it an older one, or a newer one? The difference is that the newer
versions have "protection" devices built into them that make them almost
useless for TC use without surgery. If so, there's always microwave oven
transformers. Gutting a microwave isn't all that difficult, and they're
always available at yard sales.
For more details on that I really suggest the Tesla coil mailing list
archives, and/or a tour of the webring.
snip
How would one go about building a beer bottle cap?
Don Bruder gave good advice. I'd add that the hardware that actually
touches the salt water ought to be galvanized because salt water is
corrosive. One other thing; this is for a school project and they might
or might not get a little cranky if the bottles are identified by their
previous contents. ;>)
Mark L. Fergerson |
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Blackbeard
Guest
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| Posted:
Wed Feb 02, 2005 9:07 pm Post subject:
Re: TESLA COIL (0/1) |
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Sounds like you either need to install a hammer arrester or a pressure
reducing valve. You can buy a hammer arrester that will screw right
onto the threads of your stop vavle. Then you connect your water
supply tube to the auxilliary threads on the the new hammer arrester.
That's probably your cheapest solution. The threaded hammer arrester
will cost you approx. $20. I would try the hammer arrester. If that
works, don't worry about that PRV
On 1 Feb 2005 18:22:24 -0800, "Bill Bowden" <wrongaddress@att.net>
wrote:
| Quote: | If you have a plumbing question, I'm your guy.
Electronics...nada from me.
I have a plumbing question. I get this loud humming
noise from my water pipes when I shut off the water
after taking a shower. I can't find any leaks and if
I flush the toilet, the noise goes away and doesn't return
until next time I run the hot water for some time.
Any idea what is going on with the water pipes?
-Bill |
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Blackbeard
Guest
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| Posted:
Wed Feb 02, 2005 9:15 pm Post subject:
Re: TESLA COIL (0/1) |
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So where would I purchase two of those "bullet proof" caps. Sounds
like that might be the best way to go. May not have time to find them
and use them before his science fair is due (Feb 17th). But if he gets
wimpy streamers, I'm sure he'll want to mess with this thing to get
more bang for his buck.
He's also been very impressed with pictures of people somehow routing
the lightening through their bodies and shooting bolts of lightening
from their fingerstips. He's found pics on the internet where people
have done that. I told him we had no way to test the current and no
equipment to check if it would be safe (basically, keep your grubby
hands off). It is my understanding that at the high voltage, it would
kill him so fast he'd never know he'd been zapped. He's already been
bitten by that transformer. It made an impression. He's been a lot
more careful since that transformer bit him
On Tue, 01 Feb 2005 09:18:15 -0700, Mark Fergerson <nunya@biz.ness>
wrote:
| Quote: | Vidor Wolfe wrote:
"Mark Fergerson" <nunya@biz.ness> wrote in message
news:bOtLd.4534$6u.1006@fed1read02...
Blackbeard wrote:
Snipped...
We are using a 15,000-volt neon transformer for power.
Is it an older one, or a newer one? The difference is that the newer
versions have "protection" devices built into them that make them almost
useless for TC use without surgery. If so, there's always microwave oven
transformers. Gutting a microwave isn't all that difficult, and they're
always available at yard sales.
Another excellent transformer is the OBIT (Oil Burner Ignition Transformer.)
Generally 10KV at 20+mA and to my mind, "bullet proof!"
I've used two 10KV at 23mA in parallel on a 4" coil and gotten 30"
streamers.
Yeah, I forgot about those. Bullet-proof indeed; I managed to short
one with a really poorly-built Jacob's ladder, but it worked fine after
I unscrewed the mechanical setup.
How would one go about building a beer bottle cap?
Don Bruder gave good advice. I'd add that the hardware that actually
touches the salt water ought to be galvanized because salt water is
corrosive. One other thing; this is for a school project and they might
or might not get a little cranky if the bottles are identified by their
previous contents. ;>)
And watch out for Hydrogen generation in the caps...
Right. Bubbles are Bad Signs.
Further to my previous postings, MMC (Multi Mini Capacitor) are really the
cheapest, most reliable way to go with an almost home made cap.
Yeah, but bottle dielectric punctures are easier to fix. ;>)
Not that I'm trying to stop an experiment, but I've never had brilliant
results with beer bottle or glass plate caps.
It's a school project. Explaining its failure modes is better than
having it work perfectly and not being able to explain why.
Mark L. Fergerson |
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Mark Fergerson
Guest
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| Posted:
Wed Feb 02, 2005 10:39 pm Post subject:
Re: TESLA COIL (0/1) |
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Blackbeard wrote:
| Quote: | So where would I purchase two of those "bullet proof" caps. Sounds
like that might be the best way to go. May not have time to find them
and use them before his science fair is due (Feb 17th). But if he gets
wimpy streamers, I'm sure he'll want to mess with this thing to get
more bang for his buck.
|
Sorry, should have been clearer. We were talking about a transformer
that's found in home heating systems that burn fuel oil (hence the name,
Oil Burning Ignition Transformer, or OBIT). It provides high voltage
from line voltage like neon or microwave oven transformers (MOTs), but
with more current capability, and they're more tolerant of situations
that draw lots of current without catastrophic failure, hence
"bulletproof". That greater current that most neon or MOTs means they
should be handled with extra care.
| Quote: | He's also been very impressed with pictures of people somehow routing
the lightening through their bodies and shooting bolts of lightening
from their fingerstips. He's found pics on the internet where people
have done that. I told him we had no way to test the current and no
equipment to check if it would be safe (basically, keep your grubby
hands off). It is my understanding that at the high voltage, it would
kill him so fast he'd never know he'd been zapped.
|
NO!!! DO NOT LET HIM DO THIS!!! Better he takes up ballet or something.
There was a guy who knew exactly what he was doing, giving
performances including this same "trick". He took every possible
precaution and still got killed in front of an audience. All it takes is
one tiny mistake.
| Quote: | He's already been
bitten by that transformer. It made an impression. He's been a lot
more careful since that transformer bit him
|
Good! Pain tells us not to do that again! The guy that died was
operating a fairly large coil running hundreds of watts. As long as
you're using a neon or MOT, getting zapped by the TC's output should be
shocking, but not fatal. Just don't tempt fate. Remind your son that
OBIT also stands for obituary.
BTW, I can't find your schematic on a.b.s.e. What title did you use?
Mark L. Fergerson |
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Don Bruder
Guest
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| Posted:
Thu Feb 03, 2005 5:03 am Post subject:
Re: TESLA COIL (0/1) |
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In article <l9r1011h64k52sk4lei7mnmch02qdii4et@4ax.com>,
Blackbeard <Blackbeard_The_Great@Lycos.com> wrote:
| Quote: | So where would I purchase two of those "bullet proof" caps. Sounds
like that might be the best way to go. May not have time to find them
and use them before his science fair is due (Feb 17th). But if he gets
wimpy streamers, I'm sure he'll want to mess with this thing to get
more bang for his buck.
He's also been very impressed with pictures of people somehow routing
the lightening through their bodies and shooting bolts of lightening
from their fingerstips.
|
Special protective gear and specific knowledge allows that. Even with
the right stuff and the proper know-how, one tiny mistake and you're
suddenly either very dead, or reduced to the mental capacity of an
eggplant, the mobility of a rock, and breathing only with the help of a
respirator.
He's found pics on the internet where people
| Quote: | have done that. I told him we had no way to test the current and no
equipment to check if it would be safe (basically, keep your grubby
hands off).
|
Good concept until he knows a *WHOLE LOT* more than he currently (no pun
intended, but since it's there...) does.
| Quote: | It is my understanding that at the high voltage, it would
kill him so fast he'd never know he'd been zapped. He's already been
bitten by that transformer. It made an impression. He's been a lot
more careful since that transformer bit him
|
The frequency makes it safer - Note *SAFER*, not *SAFE* - to be messing
with it, but the voltages and current levels involved are more than
capable of killing if there's even a small mistake.
--
Don Bruder - dakidd@sonic.net - New Email policy in effect as of Feb. 21, 2004.
Short form: I'm trashing EVERY E-mail that doesn't contain a password in the
subject unless it comes from a "whitelisted" (pre-approved by me) address.
See <http://www.sonic.net/~dakidd/main/contact.html> for full details. |
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Blackbeard
Guest
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| Posted:
Thu Feb 03, 2005 11:35 am Post subject:
Re: TESLA COIL (0/1) |
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I posted those pics in
alt.binaries.schematics.electronic
titled Tesla Coil Science Fair Project
I wish I knew more about how to help the kid succeed. He's had a
fairly tough tumble through school. He gets his attention by showing
his ass. He's never received any recognition for doing good work.
That's why I'm bugging you guys. If this thing works for him, this
will be the first time in his life that he'll get to experience real
pride up close and personal. I'm keeping my hands off this one and
just sorta guiding him along the best I can. When he flips that switch
and at the science fair, I think he's going to get their attention. It
could be the start of this kid realizing that real praise feels pretty
damn good vs. the snickering approval he gets from his classmates for
making an ass out of himself.
At this point, I think we have the thing just about finished. He's
wrapped 6 beer bottles with aluminum foil and filled them with salt
water topped with oil. He re-did the spark gap with 2-mm of space
between each piece of copper. I think all he has to do now is run a
little wiring and turn it on.
Anything special I need to know? Can he turn this thing on inside the
house or do we need to carry it out into the yard and use a drop cord?
After he turns it on, what should we expect? Will it take a few
minutes to fire up or will it start shooting sparks pretty quick? I'm
pretty excited for the kid. I sure as hell hope he pulls it off.
thanks for all the assistance you guys have offered. It's helped fill
in the blank spots.
On Wed, 02 Feb 2005 09:39:48 -0700, Mark Fergerson <nunya@biz.ness>
wrote:
| Quote: | Blackbeard wrote:
So where would I purchase two of those "bullet proof" caps. Sounds
like that might be the best way to go. May not have time to find them
and use them before his science fair is due (Feb 17th). But if he gets
wimpy streamers, I'm sure he'll want to mess with this thing to get
more bang for his buck.
Sorry, should have been clearer. We were talking about a transformer
that's found in home heating systems that burn fuel oil (hence the name,
Oil Burning Ignition Transformer, or OBIT). It provides high voltage
from line voltage like neon or microwave oven transformers (MOTs), but
with more current capability, and they're more tolerant of situations
that draw lots of current without catastrophic failure, hence
"bulletproof". That greater current that most neon or MOTs means they
should be handled with extra care.
He's also been very impressed with pictures of people somehow routing
the lightening through their bodies and shooting bolts of lightening
from their fingerstips. He's found pics on the internet where people
have done that. I told him we had no way to test the current and no
equipment to check if it would be safe (basically, keep your grubby
hands off). It is my understanding that at the high voltage, it would
kill him so fast he'd never know he'd been zapped.
NO!!! DO NOT LET HIM DO THIS!!! Better he takes up ballet or something.
There was a guy who knew exactly what he was doing, giving
performances including this same "trick". He took every possible
precaution and still got killed in front of an audience. All it takes is
one tiny mistake.
He's already been
bitten by that transformer. It made an impression. He's been a lot
more careful since that transformer bit him
Good! Pain tells us not to do that again! The guy that died was
operating a fairly large coil running hundreds of watts. As long as
you're using a neon or MOT, getting zapped by the TC's output should be
shocking, but not fatal. Just don't tempt fate. Remind your son that
OBIT also stands for obituary.
BTW, I can't find your schematic on a.b.s.e. What title did you use?
Mark L. Fergerson |
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John Popelish
Guest
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| Posted:
Thu Feb 03, 2005 12:01 pm Post subject:
Re: TESLA COIL (0/1) |
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Blackbeard wrote:
(snip)
| Quote: | Anything special I need to know? Can he turn this thing on inside the
house or do we need to carry it out into the yard and use a drop cord?
After he turns it on, what should we expect? Will it take a few
minutes to fire up or will it start shooting sparks pretty quick? I'm
pretty excited for the kid. I sure as hell hope he pulls it off.
|
It will be going full blast in no more than .008 seconds ( a half line
cycle) after it is powered on. You can try it in the house, but I
would turn the computer and television off, first. Run it for a few
seconds and turn it off, unplug it, short the capacitors out with a
bit of high voltage wire and look everything over for signs of
heating, arching or other problems. Work your way up to longer tests,
but keep them under a minute and leave a few minutes cooling off
between them because this thing will probably wipe out television and
radio reception (including police, air traffic control and ambulance)
for the neighborhood.
--
John Popelish |
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Don Bruder
Guest
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| Posted:
Thu Feb 03, 2005 3:24 pm Post subject:
Re: TESLA COIL (0/1) |
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In article <4201BE21.B4276F6C@rica.net>,
John Popelish <jpopelish@rica.net> wrote:
| Quote: | Blackbeard wrote:
(snip)
Anything special I need to know? Can he turn this thing on inside the
house or do we need to carry it out into the yard and use a drop cord?
After he turns it on, what should we expect? Will it take a few
minutes to fire up or will it start shooting sparks pretty quick? I'm
pretty excited for the kid. I sure as hell hope he pulls it off.
It will be going full blast in no more than .008 seconds ( a half line
cycle) after it is powered on. You can try it in the house, but I
would turn the computer and television off, first. Run it for a few
seconds and turn it off, unplug it, short the capacitors out with a
bit of high voltage wire and look everything over for signs of
heating, arching or other problems. Work your way up to longer tests,
but keep them under a minute and leave a few minutes cooling off
between them because this thing will probably wipe out television and
radio reception (including police, air traffic control and ambulance)
for the neighborhood.
|
What John said, but personally, I'd go with *OUTSIDE*, *AWAY* from any
conductive "stuff" that isn't absolutely needed in the immediate
vicinity. It might be a good idea to take a metal folding chair with any
rubber/plastic on the legs removed, and place it nearby as a place to
encourage any sparks to go should it fire up spectacularly on the first
attempt, but *DON'T* get the hopes up real high at first. As Mark (I
think it was) mentioned, tuning a coil can be tricky until you get a
feel for the one you've got in front of you. It may take some
substantial fiddling to get it tuned up the the point of doing more than
buzzing and maybe glowing. But that's half the fun, sez Don :)
If it doesn't fire up at first, make sure to POWER DOWN AND SHORT THE
CAP USING A HEAVY, VERY WELL INSULATED WIRE BEFORE DOING ANYTHING THAT
EVEN RESEMBLES TRYING TO ADJUST IT! Personally, I'd suggest building a
conveniently placed "Short-out pad" somewhere so you can just use a
broom handle (Wooden, of course...) to mash a tab into contact with a
button and positively drain the cap.
Trying to adjust one of these guys while it's powered up is a good
recipe for a Darwin award if you don't know what you're doing, and do it
exactly right. Even the folks that pass as experts (as much as anyone
can be said to be an expert on Tesla coils, anyway) on these things
won't mess with a "live" one without *VERY* specific circumstances being
met, and the utmost caution. And with good reason! You truly are playing
with "miniature lightning", and just like the full-sized version, it'll
kill you deader than last week's chicken dinner before you can bat an
eye if you don't deal with it as the potentially deadly item that it is.
--
Don Bruder - dakidd@sonic.net - New Email policy in effect as of Feb. 21, 2004.
Short form: I'm trashing EVERY E-mail that doesn't contain a password in the
subject unless it comes from a "whitelisted" (pre-approved by me) address.
See <http://www.sonic.net/~dakidd/main/contact.html> for full details. |
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Vidor Wolfe
Guest
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| Posted:
Fri Feb 04, 2005 1:02 am Post subject:
Re: TESLA COIL (0/1) |
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|
"Blackbeard" <Blackbeard_The_Great@Lycos.com> wrote in message
news:l9r1011h64k52sk4lei7mnmch02qdii4et@4ax.com...
| Quote: | So where would I purchase two of those "bullet proof" caps. Sounds
like that might be the best way to go. May not have time to find them
and use them before his science fair is due (Feb 17th). But if he gets
wimpy streamers, I'm sure he'll want to mess with this thing to get
more bang for his buck.
He's also been very impressed with pictures of people somehow routing
the lightening through their bodies and shooting bolts of lightening
from their fingerstips. He's found pics on the internet where people
have done that. I told him we had no way to test the current and no
equipment to check if it would be safe (basically, keep your grubby
hands off). It is my understanding that at the high voltage, it would
kill him so fast he'd never know he'd been zapped. He's already been
bitten by that transformer. It made an impression. He's been a lot
more careful since that transformer bit him
|
The OBITs can be obtained secondhand from oil fired boiler maintenance
companies, scrapyards (free?) etc.
The caps... Well, tell us the value you need and we/I can tell you what you
need to buy.
You need Pulse caps of anything over 600v each ideally and values of 0.1uF,
0.68uF, 0.47uF are good starters.
I've used all of the above values, each rated at 1500V.
Ten of these in series will give 15000V working voltage. Really, you need at
least 15 in series to keep the cap safish from breaking down.
However, all of these caps in series will make the value quite small and to
bring the value up, we need to have lots of these "strings" in parallel.
Therefore, working with some of the coils I've built using similar values
and voltages, 45 - 60 caps (assuming you're using 1500V ones and not a lower
value) would be a good ballpark figure you should budget for.
At 50pence/cents per cap £23 - $23 to £30 - $30 for a reliable capacitor's
not too bad a price for success.
Of course, the bottle cap would be free.
Don't do the Electric Man stunt! Ever!
A few people in the TCBOUK do this using sophisticated wire harnesses and
power engineers chain mail suits/gloves.
It's not all it seems and these days we have a better understanding of the
"skin effect" and the human body.
The skin effect is for metal conductors and not humans.
You also have to take into account that the high frequency streamer can have
a 50/60Hz component. Not to mention if there's a fault and you get a primary
to secondary strike with a good high current 15000V straight up the
secondary.
Unless someone would like to put me right of course.
Cheers.
Mark. |
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Vidor Wolfe
Guest
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| Posted:
Fri Feb 04, 2005 1:13 am Post subject:
Re: TESLA COIL (0/1) |
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"Blackbeard" <Blackbeard_The_Great@Lycos.com> wrote in message
news:2gd301dtjmeige0lvorv7q63k4kgu44m1u@4ax.com...
| Quote: | I posted those pics in
alt.binaries.schematics.electronic
titled Tesla Coil Science Fair Project
I wish I knew more about how to help the kid succeed. He's had a
fairly tough tumble through school. He gets his attention by showing
his ass. He's never received any recognition for doing good work.
That's why I'm bugging you guys. If this thing works for him, this
will be the first time in his life that he'll get to experience real
pride up close and personal. I'm keeping my hands off this one and
just sorta guiding him along the best I can. When he flips that switch
and at the science fair, I think he's going to get their attention. It
could be the start of this kid realizing that real praise feels pretty
damn good vs. the snickering approval he gets from his classmates for
making an ass out of himself.
At this point, I think we have the thing just about finished. He's
wrapped 6 beer bottles with aluminum foil and filled them with salt
water topped with oil. He re-did the spark gap with 2-mm of space
between each piece of copper. I think all he has to do now is run a
little wiring and turn it on.
Anything special I need to know? Can he turn this thing on inside the
house or do we need to carry it out into the yard and use a drop cord?
After he turns it on, what should we expect? Will it take a few
minutes to fire up or will it start shooting sparks pretty quick? I'm
pretty excited for the kid. I sure as hell hope he pulls it off.
thanks for all the assistance you guys have offered. It's helped fill
in the blank spots.
I've run 2" coils indoors and bigger at Teslathons. |
However, the garage or other such place is best.
Outside in the UK is generally a pain.
Wind can reduce streamers, I know from experience. And damp? Always a worry.
The other thing to remember, apart from keeping it away from any electrical
appliance, is to use a good RF earth, not connected to the house wiring or
plumbing.
A good length of copper pipe in the damp earth is good.
Also remember that moving a coil from location to location can change the
tuning.
Always have a tweak for best performance in 1/4 to 1/2 turns on the primary.
Never adjust a coil when energised and always discharge the caps to RF earth
via a wand and thick wire.
Leave the wand attached to the primary or cap when the coil is being worked
on.
The caps will probably be electrically leaky and the charge will possibly
bleed off quickly, but that is an unknown in the is case.
Aklways manually discharge.
Good luck.
Mark H. |
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Larry Brasfield
Guest
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| Posted:
Sat Feb 05, 2005 4:13 am Post subject:
Re: TESLA COIL |
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Not much electronics in this post. You've been warned.
"Blackbeard" <Blackbeard_The_Great@Lycos.com> wrote in message
news:75mnv0t7knvc32gm7bcf5csujav2odku1s@4ax.com...
| Quote: | My kid is building a tesla coil for his science fair project.
|
From what you've written about this, I hope it does not
become a disappointment or problem. So I offer this
unsolicited advice:
Your son, or somebody on his behalf, should get this
demonstration approved before the big day. If this
has not been done, with safety procedures and signs
in place that are satisfactory to whoever is in charge
of the fair, there is a good chance that somebody in
chage will freak out when the Tesla coil is run, and
shut it down for the day. And I would not count on
such people to be technically savvy enough to know
what the real hazards are versus imagined hazards.
That is why some early discussions are in order.
--
--Larry Brasfield
email: donotspam_larry_brasfield@hotmail.com
Above views may belong only to me. |
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Blackbeard
Guest
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| Posted:
Sat Feb 05, 2005 9:39 pm Post subject:
Re: TESLA COIL |
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Larry,
Thanks for your thoughts regarding safety. Once we get "first light"
we've already arranged a face-to-face meeting/demonstration with the
electronics instructor at the community college. The guy has a PhD and
lots and lots of experience. This fellow is our last stop before my
son placed his project in the science fair. The school gave us a
couple of extra days because they agree the this meeting will be
important.
In addition, the instructor at the community college has already shown
him how to read the wiring diagram. He's learned quite a bit from this
one project. We're putting on our final touches today (I hope). Our
first 1/2-dozen attempts failed to produce streamers. But I think
we're close.
We went ahead and found a plastic storage box that houses all the high
voltage stuff nicely and keep them out-of-reach from the curious. He's
pretty jived by this whole thing. He's already talking about building
his next coil and he hasn't finished his first.
The is another fellow who is an electrical engineer who has given him
some help. He's also talked to a motor shop where they re-build
electric components. So he's doing all the footwork. Can't figure out
why it hasn't worked yet. But I think it's going to be pretty great
when it does.
thanks
mike
On Fri, 4 Feb 2005 14:13:30 -0800, "Larry Brasfield"
<donotspam_larry_brasfield@hotmail.com> wrote:
| Quote: | Not much electronics in this post. You've been warned.
"Blackbeard" <Blackbeard_The_Great@Lycos.com> wrote in message
news:75mnv0t7knvc32gm7bcf5csujav2odku1s@4ax.com...
My kid is building a tesla coil for his science fair project.
From what you've written about this, I hope it does not
become a disappointment or problem. So I offer this
unsolicited advice:
Your son, or somebody on his behalf, should get this
demonstration approved before the big day. If this
has not been done, with safety procedures and signs
in place that are satisfactory to whoever is in charge
of the fair, there is a good chance that somebody in
chage will freak out when the Tesla coil is run, and
shut it down for the day. And I would not count on
such people to be technically savvy enough to know
what the real hazards are versus imagined hazards.
That is why some early discussions are in order. |
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