Re: Mini OLTC is working!

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

Original poster: "Stephen Conner by way of Terry Fritz <teslalist-at-qwest-dot-net>" <steve-at-scopeboy-dot-com>

At 18:37 04/03/03 -0700, you wrote:
>Original poster: "Terry Fritz" <teslalist-at-qwest-dot-net>
>
>Hi Steve,
>
>WOW COOL!!!
>
>I am happy to see you driving the IGBTs with like 30 volts.  They like 
>that ;-))

yeah sometimes you just got to be cruel to be kind!

>I am happy to see you got great results and innovated on some things and 
>your's did not blow up either ;-))  OLTC's seem pretty darn tough.  I 
>think because we us conventional components pretty much like they are 
>supposed to be over stressed ;-))

Steady on, it only ran for 2 minutes, it could still blow up yet! The main 
worrying effect I noticed is that the DC charging circuit also acts as a 
boost converter. (This is like the inductive kickback effect in NST coils.) 
So my tank cap charges to more than twice the supply rail, depending on the 
IGBT 'ON' time. At the moment it's like 2.5 to 3 times which could easily 
over-volt the IGBTs and blow them out. I need to do something about that by 
reducing the 'ON' time and/or making the choke larger, or installing a buck 
converter to cancel out the boost.

>I wonder if your OLTC could be adapted to a simple PC board Tesla coil 
>design.  Just a PC board with normal components plugged into the wall and 
>the coil to make a nice little TC without the usual high voltage 
>hassels.  It would be cool to have a nice little TC design that was pretty 
>conventional and CE mark friendly that would also be adaptable to be made 
>by the "mass produced PC board electronic stuff" techniques.

Heh! A Tesla coil with a CE mark, that'll be the day! Technically I guess 
it would be easy to put the whole circuit including primary coils onto a 
PCB, and you would just sit the secondary coil on top of the board.