Re: New DRSSTC first light and a question

["Tesla list" <tesla@xxxxxxxxxx>]

Original poster: Steve Ward <steve.ward@xxxxxxxxx>

Where exactly did you place the CT?  You didnt put it on the "hot" 
side of the primary did you?  You want it to be on the output of the 
H-bridge, and not at the junction of Cp and Lp where considerable 
voltage will be present (many kV).

My CTs *NEVER* run warm at all (even when pushing my large coil with 
1000A pk and 9000W input power).

How many turns are on the secondary of the CT?  For using a single 
core, you should have maybe 200 turns on it.  OR, you can do as i 
have and wind a pair of 1:33 turn CTs, and have the first CT's 
secondary feed the next CT's primary.

When you say "the feedback winding is one turn on the core", do you 
mean the output has only 1 turn?  That would be *Really* bad.

Steve

On 9/17/05, Tesla list <<mailto:tesla@xxxxxxxxxx>tesla@xxxxxxxxxx> wrote:
Original poster: Skip Greiner <<mailto:sgreiner@xxxxxxxxx>sgreiner@xxxxxxxxx>

Hi all
Here is a quick spec on the new DRSSTC
I used Dan's full H bridge driver but with primary feedback driving
four IRG4PC40W  IGBTs
Secondary: Dia: 4.5", 1000 turns #26
Primary: Dia: 6.5", 5 turns #10
Cap: .04
Top load: 2" x 8" toroid
Resonant Freq: 285 khz
Power: DC using a full wave bridge on 115vac input. I expect to go to
240vac input
At 40vac input the output spark is over 6"

To obtain the feedback I run one of the primary leads through a
toroid core. The feedback winding is one turn on the core.

Problem:  The toroid core get VERY hot running at 40vac input. Too
hot to touch. Is there a better way to develop the feedback????

I would appreciate any suggestions.
Skip