Tesla coil questions

[jriegle]

I find the Web to be a great source of Tesla coil design information, but
some questions I haven't found answers. Here goes...

Q1) Why is the primary typically a pancake coil set at the very bottom of
the secondary tower? Why not a concentric cylindrical coil?

My best guess that why the coil is at the bottom is to keep it as far away
from the top of the secondary as possible to keep the streamers off of it as
much as possible. No idea why the pancake coil is used.

Q2) What secondary wire gage is optimal? One site recommends #20 wire
because of the lower resistance thus higher Q of the circuit. Others use #24
wire just fine.

Q3) Building the coils will be the cheapest and easiest part for me,
therefore, I will do this part first. Before I build the supply, I will use
my high voltage supply that gets its juice from a 9v DC 300ma wall wart. The
output is from a flyback transformer and is DC. It will charge up a
capacitor I made out of aluminum foil and Mylar film and make a deafening
crack from a 1" spark. It takes a few seconds for the capacitor to charge.
I'm wondering if streamers will be emitted, although only a flash, if the
coil is pulsed only every few seconds rather than at a higher rate than the
high power supplies.

Thanks for any help, John

 

[Don Bruder]

In article <mIbkb.5918$Ec1.532603@bgtnsc05-news.ops.worldnet.att.net>,
"jriegle" <jriegle@att.net> wrote:

I find the Web to be a great source of Tesla coil design information, but
some questions I haven't found answers. Here goes...

Q1) Why is the primary typically a pancake coil set at the very bottom of
the secondary tower? Why not a concentric cylindrical coil?

My best guess that why the coil is at the bottom is to keep it as far away
from the top of the secondary as possible to keep the streamers off of it as
much as possible. No idea why the pancake coil is used.

They *CAN* be made both ways, but the explanation I've always heard, and
understand best, is that a pancake coil offers better inductive coupling
at the operating frequency, resulting in more efficient energy transfer
to the secondary, better performance overall, while maintaining maximum
isolation of primary and secondary. (So dodging the arcs is a PART of
the reason)

Q2) What secondary wire gage is optimal? One site recommends #20 wire
because of the lower resistance thus higher Q of the circuit. Others use #24
wire just fine.

That would be variable, and depend on your *EXACT* design and
operational goals. All other things being equal, smaller wire = more
turns in smaller space = better energy transfer into secondary = better
overall performnce. Trouble is, it seems that when winding a Tesla coil,
"all other things" seldom turn out to be either equal or optimal!

Q3) Building the coils will be the cheapest and easiest part for me,
therefore, I will do this part first. Before I build the supply, I will use
my high voltage supply that gets its juice from a 9v DC 300ma wall wart. The
output is from a flyback transformer and is DC. It will charge up a
capacitor I made out of aluminum foil and Mylar film and make a deafening
crack from a 1" spark. It takes a few seconds for the capacitor to charge.
I'm wondering if streamers will be emitted, although only a flash, if the
coil is pulsed only every few seconds rather than at a higher rate than the
high power supplies.

I'm thinking (not certain, since I don't know any of the rest of the
details of yout particular coil setup) that you'll probably cook off
your wall wart (and maybe more of your power supply circuit besides) the
first time you try to fire the coil.

--
Don Bruder - dakidd@sonic.net <--- Preferred Email - SpamAssassinated.
Hate SPAM? See <http://www.spamassassin.org> for some seriously great info.
I will choose a path that's clear: I will choose Free Will! - N. Peart
Fly trap info pages: <http://www.sonic.net/~dakidd/Horses/FlyTrap/index.html>

 

[Watson A.Name - "Watt Sun]

In article <mIbkb.5918$Ec1.532603@bgtnsc05-news.ops.worldnet.att.net>,
jriegle@att.net mentioned...

I find the Web to be a great source of Tesla coil design information, but
some questions I haven't found answers. Here goes...

I thought _all_ TC questions were answered on the Web. Not much left
to the imagination, is there? Besides, there are a lot of websites
with builder/operators of TCs that you could contact thru email.

Q1) Why is the primary typically a pancake coil set at the very bottom of
the secondary tower? Why not a concentric cylindrical coil?

My best guess that why the coil is at the bottom is to keep it as far away
from the top of the secondary as possible to keep the streamers off of it as
much as possible. No idea why the pancake coil is used.

Some coils are conical. Dunno why.

Q2) What secondary wire gage is optimal? One site recommends #20 wire
because of the lower resistance thus higher Q of the circuit. Others use #24
wire just fine.

Depends on how big the TC is. What did you have in mind? I've played
with - literally held my hand to - desktop sized TC toys when I was
young. They use much smaller wire than the ten foot monsters we see
today.

Q3) Building the coils will be the cheapest and easiest part for me,
therefore, I will do this part first. Before I build the supply, I will use
my high voltage supply that gets its juice from a 9v DC 300ma wall wart. The
output is from a flyback transformer and is DC. It will charge up a
capacitor I made out of aluminum foil and Mylar film and make a deafening
crack from a 1" spark. It takes a few seconds for the capacitor to charge.
I'm wondering if streamers will be emitted, although only a flash, if the
coil is pulsed only every few seconds rather than at a higher rate than the
high power supplies.

<Crocodile Dundee> _That's_ not a Tesla Coil, _This_ is a Tesla Coil!
http://home1.gte.net/res07cmo/hv/cole/cole.htm
http://www.mos.org/sln/toe/tesla.html

Thanks for any help, John

--
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Subject: line with other stuff. alondra101 <at> hotmail.com
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Just when you thought you had all this figured out, the gov't
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[Anthony Fremont]

"Watson A.Name - Watt Sun" <alondra101@hotmail.com> wrote in message

Crocodile Dundee> _That's_ not a Tesla Coil, _This_ is a Tesla Coil!
http://home1.gte.net/res07cmo/hv/cole/cole.htm
http://www.mos.org/sln/toe/tesla.html

Those are nice and all, but when you want impressive results, size
really matters. ;-)

http://home.flash.net/~kreld/tt2002.jpg
http://home.flash.net/~kreld/Copy%20(2)%20of%20biggspk1.jpg

michael

 

[Mark Fergerson]

Watson A.Name - Watt Sun wrote:

In article <mIbkb.5918$Ec1.532603@bgtnsc05-news.ops.worldnet.att.net>,
jriegle@att.net mentioned...

I find the Web to be a great source of Tesla coil design information, but
some questions I haven't found answers. Here goes...


I thought _all_ TC questions were answered on the Web. Not much left
to the imagination, is there? Besides, there are a lot of websites
with builder/operators of TCs that you could contact thru email.

http://www.pupman.com/

hosts an excellent mailing list. But read the FAQ first,
and check out as many of the sites in the webring as you
can. Many tutorials and plans available, for free.

Q1) Why is the primary typically a pancake coil set at the very bottom of
the secondary tower? Why not a concentric cylindrical coil?


My best guess that why the coil is at the bottom is to keep it as far away
from the top of the secondary as possible to keep the streamers off of it as
much as possible. No idea why the pancake coil is used.


Some coils are conical. Dunno why.

All kinds of arguments involving flux distribution,
coupling, impedance, and like that, as well as ducking those
nasty primary strikes.

Q2) What secondary wire gage is optimal? One site recommends #20 wire
because of the lower resistance thus higher Q of the circuit. Others use #24
wire just fine.


Depends on how big the TC is. What did you have in mind? I've played
with - literally held my hand to - desktop sized TC toys when I was
young. They use much smaller wire than the ten foot monsters we see
today.

"Ten foot monsters"? See below...

But yeah, it seems mainly to do with how much power you
plan to shove through the secondary.

Q3) Building the coils will be the cheapest and easiest part for me,
therefore, I will do this part first. Before I build the supply, I will use
my high voltage supply that gets its juice from a 9v DC 300ma wall wart. The
output is from a flyback transformer and is DC. It will charge up a
capacitor I made out of aluminum foil and Mylar film and make a deafening
crack from a 1" spark. It takes a few seconds for the capacitor to charge.
I'm wondering if streamers will be emitted, although only a flash, if the
coil is pulsed only every few seconds rather than at a higher rate than the
high power supplies.

No, you won't get streamers, you need to "ring" the thing
much more often to get decent streamer growth. A wallwart
won't cut it.

Crocodile Dundee> _That's_ not a Tesla Coil, _This_ is a Tesla Coil!
http://home1.gte.net/res07cmo/hv/cole/cole.htm
http://www.mos.org/sln/toe/tesla.html

Crikey, an impostor! _That's_ not a Tesla Coil, _This_ is
a Tesla Coil!

http://www.lod.org/teslacoils.html

<about a third of the way down, mate>


Mark L. Fergerson