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Re: Light Bulb Experiment (ala Brent Turner)



Tesla List wrote:
> 
> >From bert.hickman-at-aquila-dot-comSun Sep 15 21:41:18 1996
> Date: Sun, 15 Sep 1996 14:31:17 -0700
> From: Bert Hickman <bert.hickman-at-aquila-dot-com>
> To: tesla-at-pupman-dot-com
> Subject: Light Bulb Experiment (ala Brent Turner)
> 
> > Tesla List wrote:
> > >
> > <SNIP>
> > > >    The 'banjo' effect images are quite striking and beautiful, plus
> > > >    there are a few others showing myself sitting atop an insulated
> > > >    table tossing 4 foot sparks off metal rods and my fingers! (BTW
> > > >    I am wearing chain-mail meat cutter's gloves which are connected
> > > >    to the table via wires hidden in my sleeves.)
> > > >
> > > >    - Enjoy!
> > > >
> > > > - Brent
> > >
> All,
> 
> After looking at Brent's picture (BRENT_1.JPG) showing a 40W bulb being
> lit from current coming off his coil, I decided to replicate this on my
> 10" coil (without me being an integral part of the experiment. ;^) I
> took a standard 120V ceramic light socket and mounted it to a piece of
> wood. A short piece of magnet wire was connected to one terminal of the
> socket, and the other end was run to the reverse side of the wood block
> and secured with a piece of conductive aluminum heating-duct tape. The
> other socket terminal ran to a 1 foot piece of HV wire. By setting the
> assembly on the top of the toroid, I could position it so that the loose
> end of the HV wire just poked out from the outer edge of the toroid. Any
> current flowing through the corona would flow through any light bulb
> screwed into the socket.
> 
> I then proceeded to try various sizes of incandescent light bulbs to see
> if they would light from the current drawn by the corona coming off the
> HV wire. Although a 40 W bulb would light (orange color), I got the best
> results from 15 and 25 Watt bulbs, lighting them to almost full
> brilliance. I also succeeded in blowing out the filament of one 15 watt
> bulb - this bulb had a filament that started jumping all over the place
> once current started flowing through it, and it finally just openned up.
> I'm also thinking about getting one of those trick "party" bulbs that
> has a dancing filament to see how it would work.
> 
> Anyway... I made an interesting discovery: If I had a fairly steady
> streamer that didn't arc to gound, the 25W bulb lit up at a fairly
> bright and constant level. However, once I got heavy discharges to
> ground, the brightness level declined significantly, and my AC primary
> current climbed from about 22A to >28A off the 120V main. I don't
> understand why this should be! I would have expected that the bulb would
> brighten, since the discharge current to ground clearly seems to be much
> higher than the corona streamers. The fact that my primary current
> climbs also would suggest that I am processing more power under this
> condition.
> 
> Some other information that may be relevant... the system's 15 KV 120 MA
> neons and tank cap resonate at about 60 Hz (by design), and I'm using
> about 170 uF of PFC capacitance. The gaps are a combination of static
> and vacuum, totaling about 0.54".
> 
> Any ideas about what is going on??
> 
> -- Bert --


Bert,

The impedance of a Tesla coil's terminal is very high.  The impeadance of 
a pure air corona arc is even higher.  Thus the voltage differential 
available across the bulb is high and the current is at a maximum for 
this condition.  (It lights to a brillant glow)  When an arc strikes 
ground, the current is maximum  as the coil goes to a very low impedance, 
but the voltage across the coil and lamp are at a minimum (dim or  
invisible glow).  To light a bulb, you need both current and voltage.  
You will note that the arc current is brilliant on a ground hit. Most of 
the energy is being fed to the air arc and not the lamp.


Richard Hull, TCBOR