Re: my first secondary, and other stuff

["Gregory Hunter" <ghunter31014-at-xxxxxxxxx> (by way of Terry Fritz <twftesla-at-xxxxxxxxxx>)]

Hi Henry,

Don't worry about the ugly secondary.  It will
probably still work fine.  I've wound a few crappy
looking secondaries over the years, and they all
worked fine.

It's hard to guess how much capacitance you need for
your pulsed ignition coil power supply.  A single
750ml wine bottle is good for roughly 1500pF (1.5nF,
or .0015uF).  I'd start with one and tune up, then add
another bottle in parallel and tune up again, then add
a third bottle & retune, etc., etc., until you get max
spark length.  This will be a time-consuming process,
so budget a few hours for it.

If you want to have another go at measuring the
average output current of your ignition coil cluster,
try shorting out the HV across small flashlight bulbs
of known current rating.  Tungsten lamps make
excellent integrating devices, and they won't be
bothered by the pulsed current.

Cheers,

Greg
www.angelfire-dot-com/ga3/tesla

--- Tesla list <tesla-at-pupman-dot-com> wrote:
> Original poster: Hhchicken1-at-aol-dot-com 
> 
> Hi list 
> I'm putting the pieces together for my first coil,
> and have a couple of q's: 
> 1. My secondary i got a transformer rewind bloke to
> do me (£2), it is about 
> 13.5 inches long, 3.25 inches across and is wound
> with .315mm wire.  About 
> 800 turns i think.  Problems: 1. cardboard tube had
> a sticker on it, and 
> wasn't sanded so has some bumps (not too serious i
> think) 2. Some gaps in the 
> winding.  How badly will these affect performance? 
> I've managed to get a 
> good 4 or 5 inch section at one end that has
> virtually no gaps, so i'll use 
> that at the bottom. 
> 2.  My hv transformer:  I'm going to use a farm of
> between 2 and 4 car 
> ignition coils, driven with a series cap and dimmer
> switch off 240v mains to 
> give around 50,000v.  Any idea how much current they
> will have each? I'm 
> guessing about 1 or 2 ma. I tried to measure it but
> fried my cheap multimeter 
> :(  I need to know so i can figure out what cap
> (wine bottles probably due to 
> low budget) i'm going to use.  I know they won't
> blow up cos i've already 
> tried 2 and they work fine with the mains setup. 
> 3. What sort of width spark gap should I use for
> this coil? 
> 4.  Has anyone built a Chris Telford- style bucket
> primary?  I tried making a 
> flat and conical primary with copper pipe, but made
> a total mess of it.  The 
> primary I'll probably use is a small plastic bucket,
> wound around with normal 
> thick insulated mains cable.  I have some neat wire
> strippers so tapping 
> won't be too much of a problem. 
> 
> Thanks for your help guys, 
>             Henry Hallam 
> 
> 
> 


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