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RE: [TCML] Newbe's First Coil



Google "beer bottle capacitors"

Large and messy but bulletproof and right at the value that you need.

Dave

> -----Original Message-----
> From: tesla-bounces@xxxxxxxxxx 
> [mailto:tesla-bounces@xxxxxxxxxx] On Behalf Of Lau, Gary
> Sent: Sunday, January 31, 2010 1:17 PM
> To: Tesla Coil Mailing List
> Subject: RE: [TCML] Newbe's First Coil
> 
> Hi Charlie,
> 
> I agree with all that Matt suggested.  
> 
> Additionally, I suspect that your caps may be a problem.  
> Ceramic caps have a very high temperature coefficient, 
> meaning that their capacitance will vary as a function of 
> temperature.  So the primary tuning will rapidly drift as it 
> runs, and won't be in tune with the secondary.  I'm not sure 
> that blowing air on the caps will help; if the exterior is 
> getting warm, the interior will be MUCH warmer.  Funny that 
> only one gets warm though!
> 
> I don't see a problem now but this is something that may need 
> to be said.  It may appear that performance increases as you 
> increase the gap spacing.  You must resist the temptation to 
> do this, as having it too wide will allow voltages in excess 
> of what the OBIT can endure to develop.  
> 
> Regards, Gary Lau
> MA, USA
> 
> > -----Original Message-----
> > From: tesla-bounces@xxxxxxxxxx [mailto:tesla-bounces@xxxxxxxxxx] On
> > Behalf Of mddeming@xxxxxxx
> > Sent: Sunday, January 31, 2010 3:36 PM
> > To: tesla@xxxxxxxxxx
> > Subject: Re: [TCML] Newbe's First Coil
> > 
> > 
> > 
> > 
> > 
> > Welcome Charlie,
> > 
> > ANY coil that works on the first try IS a success!
> > 
> > Here are a  few simple suggestions that might improve your results:
> > 
> > 1) The pizza pan/ cookie tin combo  is a problem. The thin 
> edge of the pan, and the
> > sharp edges of the tin allow charge to bleed off, reducing 
> peak voltage. The fatter
> > and more rounded edge of a toroid allows more charge 
> build-up. A piece of
> > aluminum dryer duct or foil-covered Styrofoam doughnut will 
> serve you much
> > better.
> > 
> > 
> > 2) Your spark-gap definitely has heating problems. If you 
> are not yet going to use a
> > multi-gap, then at least do the following:
> > (a) Use heavier, brass, round-headed bolts or threaded rods 
> with brass balls. Brass
> > conducts heat and electricity better than steel, and larger 
> terminals mean better
> > heat dissipation. Rounded terminals mean less corona loss.
> > (b) Put a fan or other blower on the gap. Hot, ionized air 
> in and around the gap
> > causes it to fire sooner preventing full charge build-up.
> > (c) Slightly reduce your gap width. 5-6 mm (1/5 to 1/4 in.) 
> will prevent a misfire from
> > overvolting your transformer and your caps.
> > 
> > 3) Make sure that none of your OBIT HV connections are 
> mounted directly into
> > wood. Even at only a few thousand volts, wood starts to 
> become progressively
> > conductive becoming both a power drain AND a fire hazard. 
> Use ceramic or HDPE
> > insulators to support the gap and all HV wiring.
> > 
> > 4) Blow air onto your caps also. As they warm up, they 
> change value and spoil the
> > tuning, even if the heat doesn't damage them.
> > 
> >  5) It is not clear how or what you are using to keep your 
> primary turns properly
> > spaced. Also, make sure your tapping clips are not touching 
> / arcing to the turn
> > below.
> > 
> > These should be relatively inexpensive and quick 
> improvements without having to
> > rebuild everything. Let us know your progress.
> > 
> >  Matt D
> > 
> > 
> > -----Original Message-----
> > From: cbroring@xxxxxxx
> > To: tesla@xxxxxxxxxx
> > Sent: Sun, Jan 31, 2010 1:21 pm
> > Subject: [TCML] Newbe's First Coil
> > 
> > 
> > Hello to the members of this list. For no particular reason 
> I built a Tesla Coil this
> > winter. Just got it running, more or less. So (hopefully) 
> here are a couple of photo's
> > of what I put together.
> > 
> > http://img651.imageshack.us/img651/5567/1000420.jpg
> > http://img683.imageshack.us/img683/5931/1000424e.jpg
> > http://img651.imageshack.us/img651/5043/1000425.jpg
> > http://img651.imageshack.us/img651/5164/1000427.jpg
> > 
> > The transformer is a 10kv 23mA oil burner trans. Primary is 
> about 12 turns # 14
> > sold house wire 10" diameter with a couple extra taps 
> available. Secondary is 1300
> > turns #27 on 3.5 inch pvc. Spark gap is 2 nails spaced 
> about 5/16" Capacitor is two
> > 6000pF 30kv hokey puck ceramics, and one shows a slight 
> temperature rise with
> > use. Top load is a cookie tin and bent pizza pan. The 
> ground is the house wiring
> > tied in to an extensive ham radio/ lightening ground system.
> > 
> > It really doesn't work that great. I removed a coupe turns 
> and moved the tap around
> > to get the best coupling I could. I get a ring of 2 inch 
> sparks of the pizza plate. I put
> > a screwdriver on top and get 3-4 inch sparks off that. I 
> haven't tried bringing a
> > grounded probe to the top load yet. Anyway, I read that the 
> ceramic capacitors are
> > not really durable and one of mine shows some heating after 
> a minuet or so of on
> > time to. I think I need to work on that next. I expected a 
> little more out of it even with
> > the 250 watt power transformer.
> > 
> > I need to figure out how to ground the thing. I need a 
> better capacitor. I have lots of
> > big transformers and DC power supplies to play with once I 
> get the coil working a
> > bit better.
> > 
> > Any suggestions are much appreciated.
> > 
> > Charlie
> > _______________________________________________
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> > 
> > 
> > 
> > 
> > 
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