And I strongly recommend keeping the level shifter circuit in the VTTC. Without it
you won't get 18" to 23" sparks from a single 833A tube. The level shifter is
a very good and efficient circuit and is the only way to get good results from
an MOT. Regarding the shorter RF burst "off" times that Chris mentioned, I've
never seen that effect in my coils. If anything, a level shifter usually gives
an even shorter peak burst level, which makes the coil more efficient. This
is because the spark length of a VTTC depends mostly on the peak RF
burst level, rather than the average level.
Getting optimal results from a VTTC can take a LOT of fiddling around with
the coil in some cases. It's much more difficult than tuning a disruptive
spark gap coil, because multiple factors affect the output results.
John Freau
-----Original Message-----
From: Steve White <steve.white1@xxxxxxxxx>
To: Tesla Coil List <tesla@xxxxxxxxxx>
Sent: Sun, Jan 14, 2018 10:03 am
Subject: [TCML] 833a VTTC advice
I just finished my 833A VTTC today and fired it up for the first time. After tuning the primary I am getting 10" sparks. The sparks look very good and are sword-like and brushy. Is this the expected spark length for a single 833A?
I am wondering if I can get longer sparks out of this coil. I am currently not using staccato although that is planned. My coil is based on Steve Ward's single 833A design. The component values are identical to those in his schematic. The coil is pulling 10 amps. The current draw seems to max out at about 10 amps with the variac turned all the way up. I had to raise the height of the feedback coil to about 3 inches above the primary to get maximum spark length (10"). My primary taps are at the bottom of the coil. The bottom of the primary is almost even with the bottom of the secondary. I tried changing the coupling by moving the secondary up and down with no effect. The tube plate glows a bright orange color. The plate is not uniformly orange. There are 2 bright orange spots on the plate. One is at the top middle and the other is towards the bottom middle. The top middle spot is brighter.
Any suggestions or comments?
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