[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
Re: [TCML] Newbe's First Coil
Oops, Sorry about sending the dud email out. I'll blame it on a bad
mouse button.
This design of the primary was chosen for ease of construction and ease
of modification. Between preparing the wooden support rods and
winding the secondary I probably only have 20-30 minutes build time in
the primary. It only took a couple minuets to remove turns when
tuning. Next time I run the coil I'll check it for heating.
Thanks for all the advice! I stopped by Home Depot and bought some
copper pipe fittings to make a multiple segment spark gap. I think
I'll build it on heavy Bakelite rather the the plastic or pvc support I
see used in order to provide better stability if it gets hot.
Off to the garage workshop...
Charlie
-----Original Message-----
From: futuret@xxxxxxx
To: tesla@xxxxxxxxxx
Sent: Mon, Feb 1, 2010 5:31 pm
Subject: Re: [TCML] Newbe's First Coil
I used to use #12 fine stranded wire with pvc insulation for flattish
coned
primaries.
Because I used quite a few turns, often 18 turns or more, voltage
flashovers
were not
a problem with the close-wound configuration. I simply stuck a sewing
needle
into the wire to create the tap point. I then clipped an alligator
clip to the
sewing needle.
In some cases the needle glowed red hot, but it didn't seem to hurt the
coil's
performance because this resistance was only over a short distance.
This coil
was my old "research coil" which was a precursor of sorts to my TT-42
coil which
also uses a close-wound primary. However the TT-42 flat primary uses
10awg
telephone
solid ground wire for the primary. Another small coil I made which is
also
shown
at my website uses either 12awg or 14awg pvc insulated solid wire (or
is it
stranded....
hmmm, now I'm not sure?) close-wound, for the flat primary. The flat
primary
for
the TT-42 coil was tricky to wind however.
http://futuret.110mb.com
John
-----Original Message-----
From: Paul Brodie <pbbrodie@xxxxxxxxxxxxx>
To: Tesla Coil Mailing List <tesla@xxxxxxxxxx>
Sent: Mon, Feb 1, 2010 4:53 pm
Subject: Re: [TCML] Newbe's First Coil
I've considered using Monster speaker cable before, because of the
really thick
insulation. A major drawback has been the insulation and tapping the
coil. Your
idea of making a sharp probe sounds like a good, workable solution. I'm
glad to
hear it didn't present too many problems for you.
Now that you have brought this up and pointed out how well it works, I
think I
might try using it with a flat spiral on a relatively low voltage coil
I'm
building. I don't really think it will save much money, though, if any.
All of
the Monster speaker cable I have ever seen was extremely expensive,
certainly
not less than 1/4" copper tubing. I will check to see how the price
compares
now. I haven't looked at any for a long time. One really good aspect of
using
this speaker cable is that it shouldn't have the problems with
oxidizing and
starting to look like poop, the way copper tubing does, which has been
discussed
at length here recently. :-)
It appears to me that winding a flat spiral would be easier than making
a
helical coil. All I should have to do is wind it out flat on top of a
piece of
HDPE plastic. If I need to anchor it down, I can just spot weld it with
a hot
glue gun. If extra space is required between turns, in case the
insulation isn't
sufficient, it would be easy to add some by putting spacers between
turns before
gluing it in place and then removing them.
I've often wondered about using multi-stranded wire for the primary
coil because
of the high frequency skin effect and the increased surface area of all
the
small conductors. Unfortunately, I think this is defeated by the fact
that they
aren't insulated from one another, like they are in Litz wire.
Thanks for sharing your experience with this.
Paul
Think Positive
----- Original Message ----- From: "Weinhold Shannon L"
<Shannon.L.Weinhold@xxxxxxxxxxxxxxx>
To: "Tesla Coil Mailing List" <tesla@xxxxxxxxxx>
Sent: Monday, February 01, 2010 2:58 PM
Subject: RE: [TCML] Newbe's First Coil
I wind my primaries "helical" all the time and don't have any problems.
I use heavy gauge monster cable speaker wire (probably 10 ga) with the
thick rubbery insulation and it works great. I run the wire without
spacing, because the insulation alone provides about 1/4" of spacing
between conductors when two layers are stacked.
One plus to doing it this way, other than obviously being much
cheaper/having a much smaller footprint/less labor involved is that you
can use a map tack (basically a long steel tack) to tune your primary.
Just remove 3/4" insulation from your primary circuit lead-out wire and
wrap it tightly around the top of the tack, then push the tack through
the insulation to where its making good contact with the braided wire
inside. Don't mess up here or you'll end up with a loud bang and a free
swinging primary wire bouncing around like a down power line. Make sure
that the tack is pushed in from an angle and has at least 1/2 inch of
its length within the wire, and that its making good contact. (FYI, you
can't do this with solid copper wire. It will heat up and melt the
insulation and then you'll have the downed power line effect again.
Surprising the braided cable is quite resistant to heating.) This makes
for easy tuning, and when you get the tuning perfect you can simply
carve out some of the insulation and easily solder the primary wire to
the now exposed braided cable.
Flat spiral coils look pretty, but they are spendy and take up a lot of
space. Just be sure that your primary coil former is large enough in
diameter to keep from over-coupling the secondary. If you get sparks up
and down your secondary then you're over-coupled. You can always raise
up the secondary a half inch at a time by placing something under it
until you get your coupling right.
Save the flat spiral for later when you know what the heck you're doing
and you want a pretty coil. This works fine for functionality, and
tesla
map will tell you what size former you need if you enter in all the
rest
of the parameters.
Just my two cents as someone who has some different experience.
My coils can be seen on youtube here:
http://www.youtube.com/watch?v=46ZcwyTUQPc
Shannon Weinhold
Klasdja Intelligent Innovations
"The world we have created today has problems
which cannot be solved by thinking the way we
thought when we created them."
-Albert Einstein
-----Original Message-----
From: mddeming@xxxxxxx [mailto:mddeming@xxxxxxx]
Sent: Sunday, January 31, 2010 9:31 PM
To: tesla@xxxxxxxxxx
Subject: Re: [TCML] Newbe's First Coil
Hi Charlie,
I don't know anyone who uses a close-wound helical primary on a
spark-gap coil. A 3.5 in. coil could easily handle 500-800 watts, but
not with 14 ga wire as the primary coil. 6-10 ga space-wound bare wire,
or copper tubing would allow for higher peak currents for better power
transfer and allow it to function as a heat radiator also. You might
consider replacing the wooden rods with pvc pipe notched on the outer
edge to hold the wire in place. The alternative is a flat spiral coil
with 0.25 in spacing between turns. That should work up to 1 KW.
It sounds like your new toroid may be a little large for your 230W OBIT
to give consistant breakout without a point and ground rod. Be aware
now
that once you start making improvements, you will never be satisfied to
the point of not wanting to change something ;^))
Matt D.
(snip)
_______________________________________________
Tesla mailing list
Tesla@xxxxxxxxxx
http://www.pupman.com/mailman/listinfo/tesla
_______________________________________________
Tesla mailing list
Tesla@xxxxxxxxxx
http://www.pupman.com/mailman/listinfo/tesla
_______________________________________________
Tesla mailing list
Tesla@xxxxxxxxxx
http://www.pupman.com/mailman/listinfo/tesla
_______________________________________________
Tesla mailing list
Tesla@xxxxxxxxxx
http://www.pupman.com/mailman/listinfo/tesla