Re: Magnifier conversion

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

Original poster: "Antonio Carlos M. de Queiroz by way of Terry Fritz <teslalist-at-qwest-dot-net>" <acmq-at-compuland-dot-com.br>

Tesla list wrote:

 > Original poster: "Terry Fritz" <teslalist-at-qwest-dot-net>

 > I predicted the C2 would need to be 164pF.  But with the Cself of L2, the
 > wire from L2 to L3 and the corona rings, I predicted that the real C2
 > capacitor would have to be 134pF to tune this part of the system to
 > 160.0kHz.  As it turned out C2 actually had to be adjusted 133.5pF ;-)))  I
 > guess I am getting pretty good at this stuff after all these years :o)  But
 > really, the computer models predict things almost better than I can measure
 > now.  C2 just has a wire to remove bottom caps from the stack as needed:

When L3 is in place, it will add some capacitance to that node too.
A value similar to its self-capacitance.

 > for corona rings, I just bent 5/8 copper tubing on a circle and it holds to
 > the frames well with friction.  I used copper tape to make the connections:

A good construction technique.

 > So all is going very well and the actual hardware is performing as
 > predicted and designed perfectly.  I can't say enough how nice that
 > is!!  Doing these things by trail and error is a pain!!

Design a magnifier by trial and error would be really difficult, as
there are more things to adjust that the single tuning (and maybe the
coupling) of a Tesla coil.

 > Tonight I hope to get the rest put together and do some signal generator
 > testing were the signal generator is programmed with a simulated primary
 > signal.  That should confirm the rest of the tuning and all.

The simplest method is to replace the gap by a slow low-impedance
(1 Ohm) square wave generator, and look at the voltage over the
primary inductor. Adjust the primary tap (or the top load, as I
like to do) and C2 until you see a sequence of similar beats, as
obtained in the simulations. Use your hands close to the tops of
L3 and L2 to see where to go. A variable capacitor (radio type)
as C2 is useful to see what is the effect of C2. The beat sequence
appears all at once when C2 has the right value.

 > Then tomorrow, it will all go to the Denver High Voltage Meeting for first
 > light.

This will be interesting. Today I improved a bit the construction of
my magnifier driver, but didn't test it. When I was verifying a
simulation, I found a bug in one program (magsim was scaling the
Laplace transforms wrongly, but the designs were correct), and the
correction of the bug and some changes in the program (save/load
added) consumed all the time.
If someone downloaded that program, please update if from:
http://www.coe.ufrj.br/~acmq/programs

Antonio Carlos M. de Queiroz