Re: SSTC

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

Original poster: "Chris Swinson by way of Terry Fritz <teslalist-at-qwest-dot-net>" <exxos-at-cps-games.co.uk>

 >
 > Sounds like the driver is running at a very much lower frequency than
 > the coil Fres.
 >
 > Either that, or the secondary coil is being excited at higher resonances
 > each time a harmonic of the drive signal hits one.
 >
 > Remember, the driver is putting out a whole mess of frequencies, and
 > the coil responds at another whole lot of frequencies.  As you tune
 > around, when any two of these coincide, your lamp will reach a
 > brightness peak.
 >
 > Try to pin down the correct Fres of your coils and make sure that
 > the driver fundamental is initially set close.  Use the scope with
 > a short wire pickup to sample the secondary E-field.  Make sure it's
 > a nice sine wave that matches the period of the square wave drive
 > signal.
 >
 > Tuning can be acutely sensitive, and suggests some sort of automatic
 > control, either direct RF feedback, or some sort of control loop.
 > The challenge is to make sure the automatics settle on the right
 > pair of drive signal component/coil resonance, just as you are having
 > to do now manually.
 > --
 > Paul Nicholson
 > --


I'm looking into some designs on auto tuning, I dont yet see how it can be
done though it would help a lot if it could find its own tune point.  I did
test the driver and have it read out on my scope along side a 350khz wave
and the coil didn't tune at all to this point. The driver was noticably out
by somthing like 100khz or so before I found the best tune point. Makes no
sence but thats how it worked out. I will try again and try to work out
actually what frequency the coil is running at on the driver...

Chris