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Re: [TCML] hybrid coil



Hi Steve,
thanks for your feedback.
I haven't completely given up on improving the valve coil that I have built, by adding the stacato controller and a few other small mods that I have in mind. As I explained much earlier, this coil is a kind of an art piece and part of a large display, so I chose the valve coil over a SGTC becuse I wanted the arcs to be something different to what people (public) had seen before. I was well aware of the fact that the arcs would be much shorter, which is why I allowed 50kw to get the 3 meter arcs that I wanted. I have completely underestimated the power required to prduce CW arcs of this length. This project has so far been funded by a client, and I am hesitant to abandon it and fall on my sword... I can see now that doing it electronically would have been a much better way to do it, and a whole lot cheaper also. I don't really want to turn around to my client and and tell them I am scrapping the last 2 years work and starting again with someting different. I was not aware that electronic coils had come so far or I would have definately gone in that direction. Also, I had the preconcieved idea that electronics and Tesla Coils dont mix and as reliability is a big factor for my client, so I chose valves...

As for my hybrid idea, it seems the best way (with the gear I have set up) to get long arcs, is with a spark gap coil. But this wont allow me to modulate the pulse rate to play music, so I thought I could just use the valve to interupt the charging of the tank cap at the required pulse rates...

Am I correct that DRSSTC coils have no mains power transformer (ie they run off rectified mains)? I assume that they get the energy into the secondary by using a large tank cap, and run low frequency secondary coils to keep the switching frequencies down and the primary turns up? These DRSSTG boards that are availabe, do they run in pulses or CW or are they adjustable? Sorry for all the questions, but there is a good chance I will have to go this way...

Kind regards
Carlos

----- Original Message ----- From: "Steve Ward" <steve.ward@xxxxxxxxx>
To: "Tesla Coil Mailing List" <tesla@xxxxxxxxxx>
Sent: Thursday, November 18, 2010 4:25 AM
Subject: Re: [TCML] hybrid coil


Carlos,

Why not just build a DRSSTC like many of us have demonstrated, that can
*easily* make 10 foot or better sparks (and at <10kW).

About your hybrid idea, i fail to understand *why* you should need both a
spark gap AND a tube.  The tube is plenty fast for tesla switching, the
spark gap just sounds like extra losses and lack of control.  Just use the
tube and control the grid drive to do PRF modulation.

Alternately, the tube would be used as the primary switch in a class-C type
oscillator (like you already do).  As i tried to explain before,
interrupting the sparks will make them grow longer (though likely not as
long as you want). Also, with pulsed operation, you could operate with far
higher peak power on the tube, so using a lower impedance tank circuit to
get more peak power into the system (sparks!).

One other thing, i saw your toroid has 6 points on it, this is always going to greatly reduce the spark length. You really need 6 sparks going all the
time, each being really long?

Steve
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