a new OLTC

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

Original poster: Finn Hammer <f-h-at-c.dk> 

Gang,

Following Steve Connor`s design very closely, I have built this OLTC.
OLTC stands for Off Line Tesla Coil, and it means that it runns right off 
the wallplug voltage without any stepup transformer.
.
http://home5.inet.tele.dk/f-hammer/oltc.jpg

As a small OLTC novelty, it is equipped with an internal primary, something 
I have wanted to try for a long time, and circumstanses led me to it this time:

http://home5.inet.tele.dk/f-hammer/oltcgut1.jpg

And from another angle:

http://home5.inet.tele.dk/f-hammer/oltcgut2.jpg

As you all see, it is a 2 turn primary made from 2mm by 50mm copper( that`s 
80mills by 2")

One thing that appears particularly appealing to a newcomer, like myself, 
and used to static gaps/rotaty`s - is the ability to adjust the breakrate 
while the coils is running, and even the quench timing:

The bottom trace is the gate timing signal, the top one is the primary 
voltage. At this time it is about 100V although the scope says 50V (it 
doesn`t know that the probe is a X200 type.

http://home5.inet.tele.dk/f-hammer/oltcquench.jpg

Of course the bottom right situation should not be attempted at high voltage.

One may rightfully ask: Does a contraption like this one make sparks?
Well of course it does:


http://home5.inet.tele.dk/f-hammer/500Vspark.jpg

But as you all know, these pictyres tell very litle about the spark, but 
that they are there.

At 500Volts in, as much as I have dared to feed it just yet, it gives out 
20" streamers, about 50cm. That is at 800BPS
Sparks don`t look quite like what I`m used to, they seem to lack the 
clearcut destinct forked appearance of a SRSG coil.

The coil`s main caracteristics are these:

Pri C	8.1uF
Pri L	0.717uH
Sec 1700 turns on Ø 200mm by 600mm (forgot to measure inductance here...
Topload is 160mm by 600mm (6" by 24")

The design goal is a bang energy of 2.4J at 775 Volts giving a peak current 
of 2604A.

The coil is intended as a demonstration piece, 30" streamers is expected, 
and it should be able to do so, in what appears as a single shot.

Using Marco`s observation, that it takes 14 bangs to get the streamer to 
full length.

I can`t wait to get to Derby to test it all out, although getting a coil 
trough airport security may prove to be the most exiting part.

Cheers, Finn Hammer