DerStrom8
Super Moderator
Your right anything is a certain range works fine for a secondary coil. I did a lot of experements with secondary coils 950 turns is a very good place to start it is very easy to match your caps to that number of turns. If you wind 2 or 3 coils over each other 950 turns each and connect them in parallel you lower the wire resistance and the secondary coil works better. If your trying to get the absolute max out of your system tiny little things help add an extra 1/2" or more to the output sparks.
I always wondered if that would work!
CPU fan works good on a low power coils but not enough cooling for a 12 KW coil. Nice thing about a VSFFSG = Variable Speed Vaccum Fan Spark Gap is you can turn the variac and watch your output sparks get longer and shorter as the fan picks up speed. As the fan picks up speed the output sparks get longer and longer up to a certain point where they reach maximum length. Now you have 1 more adjustment that you never had before that helps you turn your TC. Richer Hall once said, VSFFSG works better than a rotor spark gap and it is much easier to build and costs less too.
This coil is only 360 watts, so I think a CPU fan would probably be sufficient for now. However, if the OP has access to a vacuum cleaner fan and motor, or if he has a variac and an AC fan, that would be even better.
So Marco, whaddaya say?
Regards,
Matt