Re: very confused coil results

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

Original poster: "Malcolm Watts by way of Terry Fritz <twftesla-at-qwest-dot-net>" <m.j.watts-at-massey.ac.nz>

Hi Chris,
           Here's a possible answer:

On 6 Apr 2002, at 21:48, Tesla list wrote:

> 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

First of all, 60Hz current does indeed flow through the primary coil 
with the gap not firing. In fact it has to in order to charge the 
primary capacitor. You may have seen quite a different result had the 
output of your transformer been rectified. That being so, it follows 
that a voltage was induced in the secondary by transformer action. So 
the thing wasn't resonating at Fr but.......  All this assumes that 
there is no wiring error in the primary circuit. Sounds to me as 
though your cap is ringing up somewhat. I'll be interested to see 
other replies to this.

Regards,
malcolm