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Re: [TCML] All of my tesla coil questions (for now)
I stock MMCs. Contact me off list for info.
On Thu, Jun 12, 2008 at 12:32 PM, Lau, Gary <Gary.Lau@xxxxxx> wrote:
> Hi Nicholas,
> Welcome to the TCML. My answers and comments interspersed. Bear in mind
> that opinions differ between individuals on this List, and not everything
> you read is correct. In building Tesla coils, there are a few things that
> are cast in stone (like you can't use electrolytic caps, you can't use solid
> state transformers), but then there's a lot of things that have a great deal
> of latitude in choosing, like NST ratings.
> > -----Original Message-----
> > From: tesla-bounces@xxxxxxxxxx [mailto:tesla-bounces@xxxxxxxxxx] On
> > Behalf Of Nicholas J. Goble
> > Sent: Wednesday, June 11, 2008 8:47 PM
> > To: tesla@xxxxxxxxxx
> > Subject: [TCML] All of my tesla coil questions (for now)
> > I figure I should introduce myself. I'm a sophomore in college,
> > studying business. I have only a basic college level physics course
> > under my belt, but I've read a lot about Tesla coils on the Internet.
> > I've always enjoyed building things and impressing people with them. I
> > think the most fun is building them though. My plan is to build a
> > small to medium coil over the summer.
> > Instead of filling the archives and your inboxes with multiple
> > questions that are unknown to me but second nature to everyone else,
> > I'll just clump them all in one big message. Here are all my
> > questions; hopefully someone can answer them:
> > 1) Do I NEED a Terry filter? I know they protect the transformer, but
> > I don't know how they work and what happens if I don't use one.
> A Terry filter, to a large degree, protects you from yourself. Very often
> beginners open their gaps too wide, or things aren't built or hooked up
> properly, and the gap is effectively not connected. Either scenario will
> cause the voltage on the NST and cap to climb to destructive levels. The
> MOV's and safety gaps in the Terry filter protect against this. In lieu of
> a Terry filter, a simple PROPERLY SET safety gap alone will be 95% as good
> as a complete Terry filter. Ask about how to set the gap, it's a whole
> other topic.
> > 2) Do I NEED a saftey gap? Again, I know they protect the transformer,
> > but I'm in the dark as to how they work and what will happen if I don't
> > use one.
> See above.
> > 3) How much should I plan on spending on a transformer (approx 10KV,
> > 30mA)? I don't want overpay because of inexperience.
> One can often get a free NST from a sign shop if you show up in person,
> speak gently and display competence without sounding cocky. Any core and
> coil (as opposed to solid state) NST can be used. I've build a very
> satisfying coil using a 4kv/20mA NST (see
> http://www.laushaus.com/tesla/minicoil.htm), so don't get hung up on
> finding a particular voltage unit, and don't believe those that say you need
> at least X kV to work.
> > 4) How do I construct an MMC? What type of circuitry do I use? I
> > can't find any concrete information on MMC's.
> There is no real circuitry beyond the capacitors, and it's generally
> considered a good idea to place a 10M 1/2W bleeder across each cap. It's
> not true that bleeders are only if you're using DC. An AC powered coil can
> still leave a charge on the cap if certain failure modes occur.
> There are a zillion types of capacitors, and very very few of them are
> suitable for use in Tesla coils, so let me simplify things. Use
> Cornell-Dubilier 942C20P15K-F caps. These are 0.15uF@2000V each. Use
> enough in series to give the correct voltage.
> > 5) Instead of building an MMC, whould it be cheaper and/or more
> > effective to build a plate capacitor out of just window glass and some
> > other metal?
> Cheaper, maybe, but it will perform poorly, and will be huge and heavy.
> > 6) This was my plan for a spark gap: Have 2 rods (preferably Tungsten)
> > form a gap inside a PVC pipe and have a fan or blower at one or both
> > ends. Will this be sufficient? Would a rotary gap be better? I just
> > don't want to be replacing the rods every time I fire this thing up.
> A rotary might be best, but is much, much more complex to build and
> requires special consideration for the cap value, and all in all, is not
> recommended for a beginner.
> A static gap, using parallel copper pipes, with a small fan blowing on it
> (you don't need a leaf blower!), is the best place to start. I have a
> variety of static gaps described on my web site
> > 7) Should I use insulated, magnetic wire on the secondary coil?
> The correct term is just "magnet wire", but yes, any magnet wire you come
> across, typically in the range of 22-32 gauge is fine. The goal is to wind
> a secondary with 800-1600 turns, so the gauge should be chosen per the coil
> form size. More of the sequence of determining sizes in
> > My biggest fear is that my coil doesn't work after all the time and
> > effort I invest into it. My second biggest fear is that it dies
> > shortly after I put it together. My third biggest fear is that I die
> > from it. I'm pretty sure I can be safe around electricity. Just don't
> > touch the thing when the cap is charged or it's plugged in, right?
> > These are all my questions for now. I appreciate all of your past and
> > future answers. This has been an extremley helpful listserve. Thanks
> > Nicholas Goble
> One often sees unremarkable results on the first try, myself included. If
> it were easy and everyone got the same results, it wouldn't be nearly so
> fun. Enjoy!
> Regards, Gary Lau
> MA, USA
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