RE: very confused coil results

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

Original poster: "Lau, Gary by way of Terry Fritz <twftesla-at-qwest-dot-net>" <Gary.Lau-at-compaq-dot-com>

A spark gap is nothing remotely like a capacitor.  A capacitor can store a
charge, a gap cannot.  A spark relies on ionized air to conduct, a
capacitor does not.  If there's no ionized air in a gap, there no light,
sound, no conduction, and no primary operation.  

I agree that the only way a bulb can light without the gap firing is if the
bulb was connected between the primary and secondary.  Or if there is a
short between the primary and secondary.

Gary Lau
MA, USA

Original poster: "David Thomson by way of Terry Fritz <twftesla-at-qwest-dot-net>"
<dave-at-volantis-dot-org>

Hi Chris,

Nikola Tesla remarked in one of his papers that he could tune a coil so well
that no action would be seen at the spark gap, even though the coil was
fully operational.  You got to remember that a spark gap is essentially a
capacitor with air dielectric.  When you run AC in the primary circuit,
power will still be in the primary circuit even though the spark gap appears
to be quiet.

What was the exact wattage of the bulb and was it incandescent or
fluorescent?  Did you have it connected _between_ the secondary and ground?

I'll try replicating this experiment to see what I get.

Dave

-----Original Message-----
From: Tesla list [mailto:tesla-at-pupman-dot-com]
Sent: Saturday, April 06, 2002 10:49 PM
To: tesla-at-pupman-dot-com
Subject: very confused coil results


Original poster: "Chris Swinson by way of Terry Fritz <twftesla-at-qwest-dot-net>"
<exxos-at-cps-games.co.uk>

Hi all,

I was doing some experimenting with some ground currents on the base of a
Tesla coil today.  I had a low wattage bulb connected and when the coil ran
it was just visible to see it light. I tried this about 10 times. Though
the odd thing is on about 4 occasions the spark gap didn't fire and the bulb
lite very bright. I did this a few more time and the coil started to spark
again, bulb was dim. I think asked my father to press the on switch so I
could watch the spark gap more closely. On pressing the switch the second
time the spark gap did not fire at all and the bulb lite bright again.  This
was very strange as the secondary can't get power if the gap does not fire!
I checked and re-checked for possible shorts from the NST to anything and
found nothing where it could "track" to ground. The NST sounded open
circuit, I say this as they make a funny buzzing ( they do anyway but not
this type of buzz) which I have heard before when the spark gaps were to
wide. I adjusted the spark gaps as wide as I could ( about double what they
were the first time ) and it still fired the spark gap.

If there was indeed a short to ground or something then it would have
bypassed the spark gaps, but they still fired.  In any case the bulb was
only connected to the secondary and ground nothing else, in which case if
there was a current flowing then it would have had to short on the secondary
coil to make contact.  I am at a total loss on why it did what it did. The
odd thing now is the spark gap fires every time, before it was intermittent.
my adjusting the gaps could have had something to do with this. I tried a
few times to make the gaps not fire but I can't get it to do it now.  The
question still remains on WHY the bulb lite when the gaps did not fire. I
can only assume a short of some kind but the only thing connected to the
bulb is the secondary coil and ground ( ground I talk of here is a ground
rod in the garden ) nothing else is connected to that ground. So even if
there was a short I doubt it would conduct though the soil outside.  I
assume theres a short from the NST ground , which is mains ground, to the
outside ground. There must be  a house earth point somewhere but even so
current can't flow.

I am open to suggestions for this puzzle!

Chris