Re: Triggered gap

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "Steve & Jackie Young by way of Terry Fritz <twftesla-at-uswest-dot-net>" <youngs-at-konnections-dot-com>

Henry,

Try this:  The trigger electrode should be coupled to your ignition coil
through a small high voltage (40 KV or so) cap.  You could try a couple feet
of large coax as your (very cheap) coupling cap.   It would be a good idea
to also hook the trigger electrode to two strings of a dozen 10 meg
resistors , with the other end of each resistor string going to the other
electrodes.  This will keep the center electrode potential midway between
the potential of the other electrodes.  By the way, I would recommend you
use 3 1" copper pipes a few inches long for your spark gap.  This will run
much cooler and reduce the potential for residual heat to ionize the air and
cause irratic gap performance.  At least experiment with a fan to blow air
through your gap.

Another idea posted here long ago is to have a series of parallel copper
pipe gaps spaced wide enough so they do not fire.  Then lay a piece of HV
wire across them (perpendicular to the pipes) and hook the other end to your
ignition coil.  The induced E-field from the wire should trigger the gap.
But be careful to not melt the wire!

Please keep us informed of your results!

--Steve

----- Original Message -----
From: "Tesla list" <tesla-at-pupman-dot-com>
To: <tesla-at-pupman-dot-com>
Sent: Thursday, April 19, 2001 8:20 AM
Subject: Triggered gap


> Original poster: "by way of Terry Fritz <twftesla-at-uswest-dot-net>"
<Hhchicken1-at-aol-dot-com>
>
> Hi list!
> I have decided to make a triggered spark gap to replace my current 'vice
and
> a nail'.  I thought I'd better post to the list before I fry myself...
> For the initial tests I will be using a NST labelled 6/35, although it
seems
> to be able to jump a gap of more than a centimeter (!). For the gap
> electrodes, I am using the Earth pins from UK mains sockets - I believe
they
> are made of copper, and they are much more substantial than the US
variant.
> I have set two of them up at a distance where the NST with tank cap
attatched
> will not bridge the gap, and have placed a third trigger electrode in the
> middle, offset by quite a large amount, so the gaps between any two
> electrodes are about equal.  With the NST and tank cap (no primary), this
> does not fire.
> For the trigger, I am using a car ignition coil powered by a dimmer switch
> and 3uF cap direct from the 240v 50Hz mains.  This produces (at a guess)
> around 40kV and when fired across a gap produces a tone that sounds quite
> like 50Hz.  I am all set to connect this to the main gap, but am unsure
how
> to safely do it.  As the ignition coil is an autotransformer, if I connect
> the HV out from the coil to the trigger electrode, and the minus terminal
on
> the coil (which is also connected to my dimmer) to one of the other
> electrodes, surely I will be almost directly connecting the HV from my NST
to
> my dimmer switch?  Another problem is that my NST is not grounded, I
realise
> that this is a must and will do that before I try anything.
>
> Thanks for any help you can give me - a schematic would be handy hint hint
:)
> Henry Hallam
>
>
>