SGTC – More Testing

After a bit of reasearch and a few more inter-club-member emails, I tried tuning my coil with an oscilloscope and signal generator to see if it made any difference to the output. The theory is to measure the resonant frequency of the secondary coil and topload and then, using this frequency, find the best tapping point on the primary to connect the power tap into.

It turns out that my coil resonates at 238kHz give or take a few hertz, and before building it, I calculated it should be 239kHz which is a very close match from theory to practice.

So off to the garden we went…

The weather was nice, dry and cold with no wind – perfect !. Following the installation of my safety spark gaps, three support legs and a few other minor tweaks, this time I was having it large! I opened up the main spark gap fully, set the input to 125v and pushed the fire buttons.


Not bad

The result was amazing, even at only half input power, opening the spark gap had increased the output dramatically. The streamers were crackling all around the topload and were about 6-8″ long, bringing in my earthed probe, I could draw lovely fat arcs about 20-25″ and it was still only at half power ! I turned up the input to 240v and hesitantly pressed the buttons. Ouch ! ! !



The streamers grew to about 30″ and were dancing wildly about looking for a target. It was totally amazing, they struck the garden table, the back door and the fence repeatedly. I was a very happy camper ! On the other hand, the noise was now deafening, it echoed around the gardens and quite a few curtains were twitching – oh dear !


Even better

I reduced the power to half way again to keep the noise down a bit and proceeded with some serious technical experiments…

1 – We tried laying a cut flower across the top and brought in the earth rod again, 15 seconds of arcing later and the flower was a smoking wreck, conclusion – I had enough power to roast a flower !
2 – The latest release of AOL browser cd was stood on top and the buttons pressed, conclusion – I had found a use for these discs at last !
3 – A large, empty saucepan was balanced upside down on top, result – it seemed to increase the arc length, especially from the handle !, conclusion – I will probably be trying a larger topload soon as it seems to help.
4 – A 60w clear bulb was put on top, result – it lit up with a plasma globe type of glow, conclusion – will definately be doing this again, also try a flourescent tube next time.

That enough noise for the neighbours this time, also the ozone stinks !!


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