RE: ignition coil based jacob's ladder...some questions

["Tesla list" <tesla@xxxxxxxxxx>]

Original poster: "Breneman, Chris" <brenemanc@xxxxxxxxxxxxxx>

First of all, I'd recommend using a battery-driven ignition coil 
driver - I just finished making one myself, and it works very 
well.  The driver I'm using is a simple circuit based on a 555 timer 
and 2N3055 transistor.  It runs off of a 12V lead acid battery.

The reason that you get sparks from both the + and - terminals is 
that they are connected internally by the primary winding.  The 
ground for the secondary winding is connected to the - terminal, and 
the - terminal is connected via an inductor (the primary winding) to 
the + terminal.  I'm not positive as to why you would get longer 
sparks from the + terminal, but it's possible that it's due to 
inductive action producing a higher voltage.  I wouldn't recommend 
drawing sparks from the + terminal because I doubt that the primary 
winding is designed to handle the output voltage.

The effect of the circuit stopping after a certain runtime and the 
lamp brightness could potentially both be due to heat building up 
somewhere.  I'm really not sure about this though.

The lamp connected to the same socket shorting could have been caused 
by high-voltage kickback from the coil.  This is one of the reasons I 
prefer running ignition coils from batteries.

If you'd like to try to make a battery-powered driver like mine, email me.

Chris

-----Original Message-----
From: Tesla list [mailto:tesla@xxxxxxxxxx]
Sent: Mon 11/27/2006 12:28 PM
To: tesla@xxxxxxxxxx
Subject: ignition coil based jacob's ladder...some questions

Original poster: "Ryckmans, Thomas" <Thomas.Ryckmans@xxxxxxxxxx>

Folks,

I would appreciate your comments on this...

http://hot-streamer.com/temp/IgnitionCoil-BasedJacobsLadder.gif

I've build a simple jacob's ladder using Greg Hunter's
(http://hot-streamer.com/greg) circuit (see gif attached) on 220V 50Hz
with a 20 uF 440V capacitor and a 800W dimmer.

I have added a 100W light bulb in parallel as a ballast (it seems that I
burn through 5A fuses slightly less fast with this setting - is this
because with this bulb the load becomes partly resistive rather than
just inductive? ).

The Jacob's ladder works fine - but there are a couple of things I don't
understand:


-after about 20 secs of operation, the lamp gets brighter (to 100% of
power) and stays there - regardless of the setting of the dimmer (which
minimum steeing is 75 W). As if the dimmer was completely conductive.
Why is this? It comes back to "normal" after unplugging

-I get sparks from the + AND the - primary plugs (but especially from +)
to the secondary pin - it seems that these are about twice longer than
the ones between the 2 narrow parts of the jacob's ladder. Why is that?
Do I need thicker cables from the secondary to the ladder? I had to cap
everything with glue from a hot glue gun (insulating tape leaked sparks
and caught fire...) - this reduced the sparks somewhat. Any ideas about
an insulation that is less messy? I'd rather not dip the whole thing in
mineral oil - this thing is running on my kitchen table!

-After about 30 sec the whole setup stops completely... then works again
after unplugging and replugging.

-My halogen lamp plugged to the same socket shorted... is this linked to
the jacob's circuit running?

I'd like to understand this and get a stable circuit before using the
setup for a small desktop tesla coil

Many thanks for your comments

Thomas