Re: DRSSTC - I think I heard Cross Conduction...

["Tesla list" <tesla@xxxxxxxxxx>]

Original poster: "colin heath" <colin.heath4@xxxxxxxxxxxx>

hi sue,
        When I build the bigger H bridge, I have to look into why I can't
use as
much top loading as Steve W. uses. I have enough extra turns available to
get it in tune, but I get smaller sparks, and it draws much more current
:-(.
Sue
 i to have found this with my coil. as well as drawing more current the
problem with noise on the electronics gets much worse!
cheers
colin

----- Original Message -----
From: Tesla list <tesla@xxxxxxxxxx>
To: <tesla@xxxxxxxxxx>
Sent: Monday, February 21, 2005 4:05 AM
Subject: Re: DRSSTC - I think I heard Cross Conduction...


> Original poster: Sue Gaeta <sgsparky@xxxxxxxxxxx>
>
> Get used it! It always happens that way. I have blown many 20A MOSFETs to
> bits, but I still have the original 10 amp fast blow fuse that I started
> out with!
>
> And everyone thought I was crazy when I said we should be using MOSFETs as
> drop in replacement for fuses :-)
>
> I have replaced all my MOSFETs with IGBTs now. Not that I thought I would
> get better performance, but I just wanted to see if burning IGBTs smelled
> any different >:]
>
> I started playing around with my coil again last week, and I added a
> 0.186uF cap in series with the primary. It is now officially a DRSSTC. My
> tuning was way too high from where I predicted it should have been when I
> swept the primary tank arrangement with the signal generator, which was
> odd. The interesting thing that I noticed was that a dip in average H
> bridge supply current, and an increase in spark length (obvious) coincided
> with resonance. Just like a real transmitter! People don't usually talk
> about tuning for a dip in supply current in this arena, but I just found
> out that it does apply here. Yes, I am pulsing the driver at 100 Hz, but I
> am talking about average current.
>
> When I build the bigger H bridge, I have to look into why I can't use as
> much top loading as Steve W. uses. I have enough extra turns available to
> get it in tune, but I get smaller sparks, and it draws much more current
:-(.
> Sue
>
> I am beefing up the traces, but I don't think anything could stop it once
> it lets go. But the breakers and fuses did not trip so the IGBTs blew
> themselves out of the circuit very quickly. Good since that really helps
> limit damage. I am using the little IGBT as fuses in that case and they
> almost worked. Maybe I need smaller IGBTs ;-))
>
> Cheers,
>
> Terry
>
>
>
>